I'"-' '" 0 '0"0 c: ::J c. '": 3 :'":! '" 􀁾􀀠IV 8 .'.?... l> a. a. iii" 􀁾􀀭􀀭􀁯􀁾􀀧􀁴􀁾􀀧􀁾 & 􀁄􀁏􀁾􀁫􀀬􀁲􀁓􀀠I MODERN ROUNDABOUT INTERCHAr-lGES December 12, 1995 Mr. Andrew C. Oakley, P.E. Huitt-Zollars. Inc. 3131 McKinney Avenue Dallas, Texas 75204-2416 ADDISON ROUNDABOUT SENSITIVITY ANALYSIS Pursuant to your request, we have completed a sensitivity analysis of the proposed roundabout design to determine how much additional traffic can be added to. the projected volumes while stil) providing a level of service(LOS) D. Our analysis consists of two different sets of calculations, one at the 50th percentile and one at the 85th percentile. Because capacity can be lower than estimated, and future demand flows can be higher than estimated, it is impossible to be 100 percent confident that future capacity needs will be met by any size of intersecUon. whether it is a roundabout type or signalized intersection. To achieve extremely high degrees of confidence--far example, 95 percent or 99 percent--it would be necessary to design unreasonably large intersections whose excess capacity would in most cases never be used. Ourston & Doctors designs its roundabouts at the 85-percent confidence level. We feel that this gives a prudent balance between security that the roundabout will provide ample capaoity and care not to waste land and pavement on unreasonably large designs. Partly because of this chosen margin of safety, all of our roundabouts are operating at Level of Service A. This is the highest level of service. It occurs when there is a large reserve of unused capacity. Our preferred analytic application. RODEL, was written to take level of confidence into account. (The assumed confidence level is given in RODEL printouts in the column headed "CL.") All other traffic emgineering analysiS of which we are aware implicitly assumes the 50'percent confidence level. This produces higher estimates of capacity than would be produced by assuming the 85-percent confidence level. 5290 Overpass F1oad, Suite 212 Santa Barbara. CA 9311' 8051683·1383 Page 2 December 12, 1995 The attached two-page explanation of confidence level is copied from the user guide to RODEL. In it are some .terms which may be unfamiliar to you. "RFC" means ratio of flow to capacity, which is the same as the United States' volume/capacity ratio. ARCADY is the roundabout analytic application of the British Department of .Transport. RaDEL is offered as an alternative to ARCADY. Insofar as the outputs of RODEL and ARCADY overlap, they are identical. RODEl Is sold under license to the Department of Transport because it draws on their' research. Our clients estimate future demand flows, which are input into RODEL. We design to meet these design volumes with the cushion provided by RODEl's 8S-percent confidence level. One can add to this cushion by inoreasing RODEL's flow factor above 100. When the flow factor equals 100, RODEl uses 100 percent of input flows. The flow factor is listed in RODEl's column headed "FlOF." To use the flow factor as well as the 85-percent confidence level is to provide a double cushion. The percent increase of the double cushion is estimated by first assuming a 50-percent level of confidence, then increasing the flow factor until the design objective is met. In this case the design objective is to achieve level of Service D. Based on the 50th percentile(Table A), an increase in projected flows of 27% in the a.m. and 31% in the p.rn. can be achieved, while still allowing for an lOS D. At the 85th percentile(Table B), an increase of 4% in the a.m. and 11% in the p.m. can be achieved, providing LOS D. If a still greater cushion is desired, it can be met by designing a roundabout with increased lane widths, longer flare lengths, andlor a larger diameter if required for geomtrics. Very truly yours. Peter Doctors, P.E. AGUREA ROUNDABOUT LEVELS OF SERVICE 12-12-95 50th Percentile Ourston. & Doctors Addison Roundabout Projected Design Flows A M PEAK HO!/B (Projected +27.0%) WHOlE LEG 1 LEG 2 LEG 3 LEG 4 LEG 5 LEG 6 ROUNDABOUT lNPlII FROM RODELOR ABCAOY flOW veh/hr 683 549 2027 632 3,891 AVE DELAY minlveh 0.04 0.09 0.77 1.19 OUTPUT AVE DELAY secNeh 2.4 5.4 46.2 71.4 DELAY seclhr 1639 2965 9364745125 143.376 AVE DELAY, secNeh 36.S LEVEL OF SERVICE D PM. PEAK HOUA (Projected +31.0%) V",HOLE LEG 1 LEG 2 LEG 3 LEG 4 LEG 5 LEG 6 ROUNDABOUf INPUT FROM BODEl OR ARCADY FLOW vehlhl 1644 555 1138 789 4.126 AVE DELAY min/veh 0.26 3.77 0.06 0.15 QUTPIIT AVE DELAY secNeh 15.6 226.2 3.6 9.0 DELAY seclhr 25646125541 4097 7101 162,385 AVE DELAY, secNeh 39.4 lEVI:L OF SERVICE D AGUREB ROUNDABOUT LEVELS OF SERVICE 12·12-95 85th Percentile Ourslon & Doctors Addison Roundabout Projected Design FlowS A.M. PEAK HOUR (Projected +4.0%) VIIl-IOlE lEG 1 LEG 2 lEG 3 LEG 4 lEG 5 lEG 6 ROUNDABOUT INfl IT FROfyl RODEl OR ARCAQ't . FLOW AVE DELAY veh/hr min/veh 625 0.05 502 0.10 1864 0.96 678 0.51 3,559 OIITPIII AVE DELAY DELAY saclveh seclhr 3.0 j 875 6.0 3012106790 57.6 30.6 17687 129,364 AVE DELAY, secNeh LEVEL OF SERVICE 36.3 0 P,M, PEA!;S HOUR (Projocted +11.0%) WHOLE LEG 1 LEG2 LEG 3 LEG 4 LEG 5 lEG 6 ROUNDABOUT INPUT FROM RODELOR ARCADY FLOW vehlhr 1556 526 1077 746 3,905 AVE DELAY min/yah 0.47 2.99 0.07 0.18 Q!UPI[[ . AVE DELAY seclveh 28.2 179.4 4.2 10.8 DELAY sec/hr 43879 94364 4523 8057 150,824 AVE DELAY, seClveh S8.S LEVEL OF SERVICE 0 • • • • 50 % Confidcnc:e Level AM Peak Hour .*t'I••t ••􀁴􀀮􀁴􀀢􀁴􀁴􀁴􀁩􀁩􀀪􀀧􀀮􀁬􀁬􀁬􀁬􀁩􀀧􀁩􀁬􀀧􀀮􀁴􀀢􀁉􀁾􀀢􀁩􀁾􀀮􀀻 •••I••ttt;1111;:."1""",,,"1.1., • 􀀱􀀲􀀺􀀱􀀲􀀺􀀹􀁾􀀠 􀁾􀁏􀁏􀁉􀁓􀁾􀁈􀀠ROUKOUOUT 101 t ••••,•••,t'••••'I•••••••••,." •• , •••••'.III'I••••••••••••t •••li'I""';,•••,'I" • % • i E (n) 10.06 7.12 10.0. 7.32 % 1m PERIOD lif' 90' t i' (Il 16.43 14093 16,60 22.13 1 TI"E SLICE lin 15 * , V (!1 Ml U2 7.01 4.12 i RESULTS PERIOD lin IS 75 , 1 􀁾􀁁􀁏􀀠 􀀨􀁾􀀩􀀠 39.63 10.29 36.58 45.73 t T1"£ C&ST pJain 1.19 s * PH! W 21.00 57.00 30.00 21.00 t flOW PERIGO tin IS 75 i •* DIA (m) 6Ua 60.98 􀀶􀀰􀀮􀀹􀁾􀀠 60.98 f flDK 􀁬􀁙􀁾􀁅􀀠 peulveh VEH' GRAD SEP 0 0 0 0 • flaM PEAK am/optp. AM' • t. "II'II'f,••t'••􀁴􀁬􀁴􀀨􀀧􀁊􀁬􀁉􀁉􀁉􀁉􀁉􀁊􀀧􀁴􀀨􀁉􀀨􀁬􀁦􀁴􀁴􀀧􀁉􀀢􀁉􀀻 􀀢􀁊􀀧􀁉􀁊􀁴􀁬􀀧􀁾􀀱􀀱􀀮􀀧•••••' •••" •••••' ••• 11 • LEG 􀁈􀁾􀁾􀁅􀀠tPCU tFlOW9 (1st axil 2nd etc ••• U)*FlOFtClt FLOW RAfIO 􀀧􀁦􀁬􀁏􀁾􀀠􀁉􀁉􀁾􀀨􀀪􀀠 • f t t II I I tkB 􀁏􀁕􀁏􀁾􀀱􀁊􀁈􀀠'!.O5' 8l 3S5 10 0 t1.27150lUS 1.125 0,75'15 45 7S * -U 􀁭􀁾􀁒􀁅􀁄􀁉􀁌􀁏􀁓􀁉􀀠 31 212 129 0 *1.27*50'0.151.125 0.1511) 45 75 , l58 QUORUM tLOSt 218 􀁉􀁏􀁬􀁾􀀠 304 0 *1.21*50'0.15 1.125 0.15'1'5 45 75 , 118 !ILORED'1.05' 118 302 18 0 '1.Z7'5O*0.15 1.125 0.15'15 45 75 • • * 1 tIt', t 'It t, I. * • 1 * ., .' U:tt:UilUiU,UtUfU"tfJur:a:.utitUlltn'-:U**UlU,tlttUt.U**u.tUtUUtU:U*fl • 􀁾􀀠 I • fLOW veh 6M 549 2021 632 t 􀁔􀁏􀁩􀁾􀁬􀀠DELMS t • CAPACHY veh 2016 1m 2m m * • • AYE OHM sins 0.04 0.01 0.11 !.I9 I 4i! nrs I f 􀁍􀁾􀀠DELAT _1M 0.06 0.13 1.78 2.61 • I *AVE QUtIJE nh I 1 27 13 181 pmds t * 􀀢􀁾􀁘􀀠QUEUE Yih 1 1 61 29 * * •* * * 􀁾􀁲􀀬􀀮􀁴􀀪􀀮􀀻􀀢􀀪􀀪􀀧􀀪􀁩􀀧􀁬􀀲􀀪􀁩􀀪􀀪􀀣􀁩􀀻􀁉􀀪􀁉􀀧􀁉􀀪􀀧􀁩􀁴􀀪􀀧􀁬􀁴􀁴􀁾􀁩􀁬􀁴􀁊􀀢􀀧􀁉􀀧􀀪􀀻􀁉􀀮􀁉􀀪•••it***.*2111*1'*,** lltl • • • • • • • • • • • • • • • 6S % Confidence Level AM Peak Hour 􀀪􀀢􀁴􀁩􀀮􀁴􀁬􀁬􀁾􀁬􀁴􀀮􀁬􀁬􀁬􀁬􀁬􀁴􀀧􀁬􀁴􀀧􀀪􀁉􀁉􀁉􀀪􀀪􀁉􀁉􀀧􀁉􀁉􀁉􀀪􀁦􀀧􀁉􀁉􀀮􀁾􀁉􀁉􀁉􀀮􀁬􀁴􀁬􀀮􀁴􀁬􀀢􀁴􀁬􀁩􀀧􀀬􀁩􀀮􀁏􀀮􀁬􀁴•••I •••I'.llll. t • t 12:12:95 􀁾􀁵􀁄􀁉􀁓􀁏􀁾􀀠RCUHDABOVf 106 • J , 11'••IIJiil'II'lltlltllllltttltl••􀀻􀁴􀁩􀁩􀁬􀁬􀁬􀀻􀁩􀁬􀁬􀁬􀁾􀁬􀁴􀁬􀁬􀁴􀀧􀀢􀀠•••••II.ltt•••I.t••IIII.t i I I (0) 􀀱􀀰􀀮􀁾􀀮􀀠 1.32 􀀱􀁾􀀮􀁏􀀶􀀠 1.32 t TIHE 􀁐􀁅􀁾􀁉􀁏􀁄􀀠 lin 90 • •t l£' (I) 16.43 14.93 16.60 22.13 1 TIME mcr lin 15 • I 􀁾􀀠 (I) 7.01 U2 1.01 4.12 t RESULTS PERIOD lin IS 15 ¥ t 􀁒􀁾􀁮􀀠 'I) 39.63 18.29 36.58 45.13 I TiHE 􀁾􀁯􀁳􀁲􀀠 p/miA 1.7? • • PHI (d) 2UO 51.00 30.00 27.00 t flON PERIOD th 1515 1 • DIA [I) 60.98 60.98 6MS 60.98 I FLO' T1P£ 􀁰􀁣􀁵􀀯􀁶􀁥􀁾􀀠 VEH I * GRAD m 0 0 0 0 • FLO" 􀁐􀁅􀁁􀁾􀀠􀁡􀀧􀁉􀁇􀁰􀁬􀁾􀁾􀀠 AM 􀁾􀀠 t *l•• tlf'l.ktI1Ij .......􀁴􀁦􀀮􀁾􀁴􀁬􀀮􀁉􀁉••*lj ••• I.II••••*.I*.ttt.lt.,.,.,!t.,llltl."". • LEG MAffE IPCU 􀁴􀁦􀁬􀁏􀁾􀁓􀀠 (lsi 8xit 2nd stc... U)tfLOftClt FLO" RAllO 'fLOW mEt * l t t • t 'HO QUORUM *I.OSI 83 las las 10 0 Jl.04lSStO.1S I.IZS 0.75115 45 7S t 1MB 􀁾􀁬􀁬􀁏􀁒􀁅􀁾􀁉􀀮􀁑􀁓􀀧􀀠 31 m 129 0 􀁴􀁬􀀮􀁏􀁾􀀧􀀸􀁾􀀧􀁏􀀮􀀱􀀵 􀀠1.125 G.7$115 4S 7S • '58 QUORUM '1.05. m lG74 􀁾􀁑􀀴􀀠 0 '1.04'B510.15 1.125 O.lSIIS .5 75 • tEi 􀁾􀁬􀁴􀁏􀁒􀁅􀁏􀁬􀁬􀀮􀀰􀀵􀀱􀀠 US .l42 18 0 '1.04'a5IO.15 1.125 0.1;'15 45 75 ,t • • • • • I • I • t j; .ttttl.l.ltl••lft••••' •••••ttl••lltl.t.I.'ltttttt**••••ttlttltlt,•• " •••t'tttl" t • t • fLON vab m 502 lS54 m • 10m DELAYS I *CAPAcm yen 1829 I!OI 􀀱􀀹􀀶􀁾􀀠 721 t • 1 AVE DEt.AY aiDs 0.05 UO D.9. 0.51 36 hrs • HAX DELAY lIilis. 0.07 0.14 2.17 1.00 • I • AVE QUt\iE vah I I 3G 5 • 161 pounds 1 • !lAX QUEUE veh 1 l 69 9 f • 50 % Confidence Level PM Peak Hour 􀀢􀁊􀁬􀁩􀁩􀁩􀀧􀁪􀁴􀀧􀁴􀁴􀁬􀁾􀁬􀀮􀁴􀁬􀀧􀁩􀁬􀁬􀀧􀀪􀁉􀁉􀀧􀁩􀁬􀀪􀀪􀁉􀀪􀁉􀁉􀁉􀁾􀁩􀁬􀀻􀀪􀀪􀀻􀁴􀁬􀁬􀁬􀀧􀁬􀁴􀁬􀁴􀀪􀀢􀀾􀀧􀁉􀁉􀁉􀁉 •••• t"I.,11111111 •• 12:12:9$ ADDISON 􀁾􀁏􀁕􀀢􀁾􀁁􀀡􀁏􀁕􀁔􀀠 105 *I •tllltltlitl.'iltillll.II'ttlllltlltltl'lti.ttltttt'ttttlltllltt,t" •••,.t.II*I••* i • t I E (,) Ji).OQ 􀀷􀀮􀁾􀀲􀀠 10.06 7.52 , mE PUIOO min 90 * 'L' tal 􀀱􀀶􀀮􀁾􀁬􀀠 14.93 16.60 22.13 • lIKE sueE lin 15 1: 1 V (I) UI 4.l2 1.01 4.12 t mOLTS PERIOD lin IS 7S I *􀁒􀁁􀁾􀀠 (0) 39.63 18.29 36.53 45.13 • tlHE COST p/,in 1.79' t PHI (d) 27.00 57.00 30.QO 27.CO • 􀁆􀁌􀁃􀁾􀀠􀁐􀁅􀁒􀁉􀁏􀁾􀀠 Bin a 75 * 'DIA (l) 60.ge 6Ua 􀀶􀀰􀀮􀁾􀀸􀀠 60.98 , flO! mE pcv/veh m' 1 Gf@S£P 0 0 6 0 *flOW pm ujop/PI PH * 􀁾􀀠 ;;;; *t.**tlll'ft**;;it.ltt*tt lttll•••tlt*.tttllI11fllt.****tllttl••tlt•••" •• , ••• I." * LtG KAME 'PCU 􀀧􀁆􀁌􀁏􀁾􀁓􀀠(1st 􀁥􀁾􀁩􀁬􀀠lnd etc.••O)'flOF'Cl* 􀁦􀁬􀁃􀁾􀀠 RATIO If(OM 􀁔􀁉􀁾􀁅􀁴􀀠 J *' t l,;t '1 J tHe 􀁑􀁾􀁏􀀧􀁏􀁈􀀠'1.05' 10 1099 􀁾􀀮􀀠 0 *1.51'5010.75 1.125 0.75'15 4S '5' ,MB 􀁈􀁬􀁬􀁄􀁾􀁅􀁄􀁴􀁬􀀮􀀰􀀵􀀪􀀠 2. 219 1[9 0 '1.51*50*0.15 1.125 0.7SI!5 4S 15 • 'S8 QUGRUK *1.05' 147 553 169 􀁾􀀠 11.31'50t O.15 1.125 0.75*15 45 15 I 'E8 􀁈􀁬􀁬􀁄􀁒􀁅􀁾􀁉􀁉􀀮􀀰􀀵􀁴􀀠 80 219 305 0 11.51t5010.1' 1.125 0.7S*15 45 1S , *' • 􀁾􀀠 I.*:t l .. 1.:1 .11 l t. • • 􀁾􀀠 , ** '* tUtUUUtUIUlltUnUUUIHlui UftU IllUIUUHUlllunUIUUUUltun • 1 1 • HOW veh 1644 lSI 1m m 1 TOTAL D€LAYS ' • CAPACITY veh 1967 5.0 2194 1224 ;; ;; t AVE DELAY lin5 0.26 􀁾􀁴􀀷􀀱􀀠 O.C6 0.. 15 I 45 hrs t t "AX DELAY Un. 0.52 l.41 US Ul * • • AVE QUEUE ¥eh 7 􀀴􀁾􀀠 ! 􀁾􀀠 • m pounds * • "AX IUEU£ veh 13 􀀷􀁾􀀠 1 l t • I • i t••;•••••••,.,••••,*••••••••,',•••••,*'.'.".'.'.'.,••"*IIIII••••••'tl""'**" 85 % Confidence Level PM Peak HotJr :lUi2U.UUl:tUUtt;titft*u**tnfuu*n*.,tt,t.JtUUUlur:tUU:UIUUt1•.Uti * • * 12: 12:95 ADDISON ROUHDABOUT 104 􀁾􀀠 l , ••••I;••;I'•••••llll•••*•••••'IIIII*III.' ••• "IIII'•••1.111;11;1111•••>.;.**1111 t t • *E (.) 10-0. 7.31 10.06 1.32 I TIHE PERIOO lin 90 t • (0) 16.4J IMl 10.60 2z.J3 • TInE HlCE 􀁾􀁩􀁮􀀠 IS t • V l' 􀁦􀁾􀁽􀀠 UI U2 7.01 4.12 t RfSUL1S PERIOD lin (5 )5, t , RhO (.) 39.63 18.29 36.58 45.13 1 1m COST 􀁰􀀯􀁾􀁪􀁮􀀠 1.19 1 I 9HI (d) 2i.OO S1.00 30.06 27.00 t HON PERIOD lin 1575 • • 􀁏􀁛􀁾􀀠 h) 60.98 60.96 60.98 6Ua • 􀁆􀁌􀁏􀁾􀀠 lY9£ pcu/vah YEH I t GRAD m 0 0 0 0 t 􀁦􀁬􀁾􀁗􀀠PEa' 􀁡􀁾􀀯􀁯􀁰􀁬􀁰􀁾􀀠 PH • • t I •• , •• ,'••••• 1 •••• ":••• '.1'.1111'1'111 •• 11111'.11111'."'''".It,,,II •• I:t.t.*•••• * LEG HAijE 'PCU 􀀧􀁩􀁌􀁏􀁾􀁓􀀠 (lsI exit 2nd eIC ..•U)lfIOF*CLi FIOM RATIO 'fLOW TI"t' • it l " 'I 'N8 UUORUH '1.05' 70 1099 .6 0 '1.11'8510.15 1.125 0.75115 45 is' tkB 􀁾􀁉􀁌􀁏􀁒􀁅􀁏􀀧􀀱􀀮􀀰􀀵􀀧􀀠 26 219 119 0 'l.W8S*O.15 I.m 0.15115 45 7S • 'S8 QUORU" *1.05' 141 553 169 0 '1.11*8510.15 1.1250.75*154575 , '£8 UWREO*l.OS' SO 219 10;; 0 􀁩􀁬􀀮􀁬􀁬􀀧􀀸􀀵􀁾􀀰􀀮􀀠7S 1.125 O.7S'lS 4S 7S x * * j , " '* · t* .r • • 1 ,. • * uu....u,u..it..,u,u••u"UUntUlllu**.niUttt.It.IIIIU..,u.tu*n.1 • t • * fLOW ..􀁾􀀠 1556 SZ6 1017 746 • tOTAL OeLAYS • *CAMWI ven 1181 m 1952 11lI ,i • *m mAY tins 0.4i 2.?9 0.07 . 0.18 4Z hrs • , "AX mAY .ins 1.01 5.92 0.09 0.29 , • • m QUEUE veh 12 30 1 2 • 195 pounds t , 􀁈􀁾􀁘􀀠 QU!.UE veh 25 57 2 3 • f • • j •••••••••t••􀀧􀁴􀁴􀁴􀁴􀁬􀁬􀁾􀀮� �􀀧􀀮􀀧􀁴􀀧􀀪􀀪􀀮􀀬••••••"" •••••••ttft••••••••,j'*'II,.:t,." ••••• :It. is not possible to est.ilrate queues arxl. Qelal'S accurately•. 'lhe.y can only be estimated for it particular confidence IGVeJ. (either .i:q>liclt or explicit). If queues am delays are estimated with a 50% confiden::e level, it is 50% oertain capaI.:lity oontain 'error'. equation has a standa:rd error of that: the actual 􀁾􀁥􀁳􀀠ani delays will not be greater than values. (apart: fran r.m:lcm variatioo) the estimated !!he delays am queues ca]c:uJal;.ed dep'md on flCM and capacity. Eoth flCM ani l-6 􀁾􀀠 0 .2 0 i 0-2 0'4 i 0-' ! 0-8 1·0 1 1·2 ... --------... ... ....... _-----.J Case 1 Calle 2 FLOW/CAPACITY FIG. 10 IlIi.lIAY /RfC In case 1 the 1I.1lo1e RFC 􀁾 is on the flat part. of the curve, an:! any value of RFC in the range will produce lao: delays. '!he delay fo:rea!.!St is therefore robJst. '. . case 2 is quite different. 'l'Ile average RFC (50\ 􀁣􀀺􀁣􀁮􀁦􀁾 1evel) has delays virt:ually the _ as Case 1. However, as case 2 is close to the ste.ep secl::ion of the curve, the possible 􀁶􀁡􀁬􀁾􀀠of RFC qreater than the 50% value. 35 have v«ry high delays. Values greater than 50% will coeur if "the i!ICI::ual flews are greater than the inp..lt fl 􀁾􀀠LINL£JFRAME io I N f •tOl ,I 􀁾􀀠 NOTE: PIPES SHALL CONNECT TO THE ENOS OR SIDES OF INLETS. m 􀁾􀀠 CONNECTION SHALL NOT BE MADE AT CORNER OR BOTTOM. PILASTER -12 &; 􀁾􀁭􀀠 􀁾􀀬􀀭􀁯􀁐􀁴􀀡􀀠 'nI 2' R 􀀬􀁴􀁯􀁊􀀢􀀬􀀬􀁾􀀠 􀁾􀀠 - POINT OF BEGINNING S 64"27'5S"E GAYLORD PROPERTIES, INC. S.26' (FORMERLY OPUBCO PROPERTIES, INC.) VOL. 82020, PG. 664 &688 N 8S046'15"E 272.159' ..&""'"-S OO"13'46"E D.R.D.C.T. I I • I a ' S 89°46' 15"V 210.30' 2,809 Sq. Ft. N 64°27'58"V 20' X 20' 10.SO' ELECTR I C ESM'T. VOL. 90241, PG. 2807 FINAL PLAT LOT I BLOCK I ADDISON CONFERENCE CENTERADDISON CENTRE THEATRE VOL. 90241. PG. 2807 D.R.D.C.T. I I I I I 20' ALLEY AND II UTILITY ESM'T. --,......; VOL. 90241, PG. 2607 i I I I I I 1 r-􀁾􀀭􀀭􀀭􀀭􀀭􀁍􀁾􀁉􀁾􀁌􀁾􀁄􀁾� �􀁾􀁅􀁾􀁄􀁾􀁾􀁓􀁾􀁔􀁾􀁒􀀭􀁅􀁾􀁅􀁾􀁔􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀁾􀀠 50' R.O.II'. VOL. I. PG. 536 JULIAN'S ADDITION • VOL. I, PG. 538 BASIS OF BEARING. M.R.D.C.T. THE FINAL PLAT OF LOT I. BLOCK I OF THE ADO ISON CONFERENCE CENTERADDISON CENTER THEATRE AS RECORDED IN VOLUME 􀀹􀀰􀁾􀁥􀁌􀁉􀀠PAGE 2807 OF THE DEED RECORDS OF 0 S COUNTY. TEXAS. lHEET 2 OF 2 HUIlT -ZOLlARS 3131 McKINNEY AVENUE/SUITE 6illil DALLAS. TEXAS 214-871-3311 EXHIBIT MAP ELECTRIC EASEMENT ALONG THE NORTH SIDE OF ADDISON CONFERENCE CENTER-ADDISON CENTRE THEATRE TOII'N OF ADDISON DALLAS COUNTY, TEXAS ERIC YA UDY . REGISTERED PROFESSIONAL LAND SURVEYOR TEXAS REGISTRATION No. 4862 OATE. JANUARY 15, 1996 LAND DESCRIPTION DRAINAGE EASEMENT BEING a tract of land situated in the G.W. Fisher Survey, Abstract No. 482, Town of Addison, Dallas County, Texas, and being a portion of Lot 1, Block 1 of Addison Conference Center-Addison Centre Theatre plat, an addition to the Town of Addison as recorded in Volume 90241, Page 2807 of the Deed Records of Dalla's County, Texas, and being more particularly descnoed as follows: BEGINNING at a one-inch iron rod found at the most easterly northeast corner of said Addison Conference Center-Addison Centre Theatre plat; THENCE, South 00 degrees 33 minutes 30 seconds East along the east line of said Addison Conference Center plat a distance of 6.00 feet to a poiDt for corner; THENCE, South 89 degrees 21 minutes 53 seconds West parallel with a north line of said Addison Conference Center plat a distance of 75.91 feet to a point for corner; THENCE, North 45 degrees 38 minutes 25 seconds West a distance of 15.52 feet to a point for corner; THENCE, North 00 degrees 41 minutes 13 seconds West parallel with an east line of said Addison Conference Center plat a distance of 197.61 feet to a point on a north line of said Addison Conference Center plat; THENCE, North 89 degrees 18 minutes 47 seconds East along a north line of said Addison Conference Center plat a distance of 6.00 feet to a northeast corner of said Addison Conference Center plat; THENCE, South 00 degrees 41 minutes 13 seconds East along an east line of said Addison Conference Center plat a distance of 202.59 feet to a 1/2 inch iron rod found with "Huitt-Zollars" cap for a corner of said Addison Conference Center plat; THENCE, North 89 degrees 21 minutes 53 seconds East along a north line of said Addison Conference CenterAddison Centre Theatre plat a distance of 80.89 feet to the POINT OF BEGINNING and CONTAINING 1,677 square feet of land, more or less. 􀁆􀁏􀁾􀀠. t-Zollars, nco Eric J. ou Registered Professional Land Surveyor Texas Registration No. 4862 Huitt-Zollars, Inc. 3131 McKinney Ave. Suite 600 Dallas, Texas 75204 (214) 871-3311 Date: January 11, 1996 lof2 G:\PROJIDI19J201 \DRAINAGE.DES 1115f96 z o til .... _Z--L:I: ::1==-=-=-_ I o 􀁾􀁯􀀠 100 􀁾􀀡􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁩􀁬􀀧􀁾􀁾􀁾􀁲􀀠 linch = I00 f t. A.J. AIROLDI VOL. 76010, PG. 1121 D.R.D.C.T. \ 20' X 20' ¢ ELECTR I C ESM' T • 􀁒􀀭􀁾􀀠q,'t-VOL. 90241. PG. 2607 O:JV 􀀮􀁾􀀠 ((-􀁾􀁯 {E) 􀀰􀀺􀁊􀁾􀀰􀀭􀀼􀀢 «"-;􀁾􀀱􀀨􀀧􀀠 􀁾􀀧􀀰􀀧􀀢􀀠 􀀰􀀧􀁾 1(' FINAL PLAT N 69" 18' 47"E 6.00' PK NAIL FOUND IN CONC. BASE Cl Of FENCE POST 2 LOT I BLOCK I 1,677 Sq. Ft. . 􀁾􀀠 ID,.•. CI) )I •,.., 􀁾􀀠 "0 0 :z en In N 􀁾􀀠 1.1.1 •,.., 􀁾􀀠 "0 0 (/) IRF 11.1 =,.., In' .(/) -10 N • . i III 􀁾􀀠 ffi! 11:1 .. 􀁬􀀡􀀻􀁾􀀠 􀀡􀀲􀁾􀀠 6· D..ADD I SON CONFERENCE CENTERN 45'38'25",* I I I I I I I I I ADD I SON CENTRE THEA TRE 15.52' VOL. 90241, PG. 2807 S 89"21'53"" D.R.D.C.T. 75.91' I 20' ALLEY AND : UTI LITY ESM' T. --rVOL. 90241, PG. 2607 11.1 • 􀁾􀀮􀀠 ;,.;.,' 8. • ID 8 (/) JULIAN'S ADDITION MIL D RED S T REET 50' R.O.". VOL. I, PG. 5:38 VOL. I, PG. 5:38 eASI. OF BEARING. M.R.O.C.T. THe; FIllA!. PUT OF 1.0T I. BI.OCK 1 OF THE ADDiSON CONFERENCE CENTERADDISON CENTER THEATRE AS RECORDED LEGEND IN VOf.UME 90241. PAGE 2807 Of" THE DEED RECORDS OF DALLAS COUNTY. TEXAS. ,HEET 2 OF 2 EXHIBIT MAP HUIlT -ZOLlARS DRAINAGE EASEMENT ALONG THE ERIC J YA DY EAST SIDE OF ADDISON CONFERENCE REGISTERED PROfESSIONAL LAND SURVEYOR 3131 McKINNEY AVENUE/SUITE 6l!I11 CENTER-ADDISON CENTRE THEATRE TEXAS REGISTRATION No. 4862 DALLAS. TEXAS 214-871-:3311 TOWN OF ADDISON DALLAS COUNTY, TEXAS DATE, JANUARY 15, 1996 , , -It ®oIsoN PUBLIC WORKS DEPARTMENT (214) 450-2871 􀁾􀀧􀀺􀀺􀀧􀀧􀀺􀀻􀀡􀁾􀀺􀀻􀀧􀀭􀀧􀀻􀀧􀀮􀀭􀀮􀀺􀀺􀀮􀁾􀁚􀀻􀀭􀀻􀀻􀁣􀀿􀀺􀀡􀀺􀁾􀁾􀀧􀁾􀁾􀁾􀀠 Post Office Box 144 􀁁􀁤􀁤􀁩􀀮􀁾􀁯􀁮􀀮􀀠Texas 75001 16801 WeslgrO\'C December 26, 1995 Mr. Andy Oakley, P.E. Huitt-zollars, Inc. 3131 McKinney Avenue, Suite 600 Dallas, Texas 75204 Re: Addison Circle -Public Infrastructure Dear Andy: '.' The following information is needed to complete the review of the plans for the public infrastructure: 1. Provide three copies of' an updated design report for the rotary. Please remove the language regarding the constrained design or provide an unconstrained design alternative. Please provide sections in the report that address grading, roadway profile, and drainage; and incorporate a full set of plans for the rotary (geometries, lighting, signage, grading, etc.) with the design report recommendations. This information is necessary for our transportation consultant to complete their review. 2. Provide a design report supported by an engineering recommendation for the use/application for the materials/elements not historically used within Addison. As a minimum, please address operation, safety and serviceability of the material/elements recommended. A. Bricks Please provide information regarding the use of the brick for roadway and sidewalk purposes. please include elements addressing the function, safety and serviceability of the proposed product. Of particular concern is the use of brick in the valley of the Mews streets and at the valley intersections where runoff/irrigation water mixed with vehicular traffic may subject them to accelerated deterioration or affect their skid resistance. Mr. Andy Oakley December 26, 1995 Page 2 B. Curbless Street/Mews Intersections Please address how this functions. Of particular concern is 'the potential for conflict between the pedestrians and vehicular traffic at these intersections and our ability to maintain signage that will not require continual replacement. C. Mid-block Crosswalks on Quorum Drive We have a number of concerns with mid-block crosswalks on streets with ultimate traffic characteristics of Quorum Drive. If you desire the proposed crosswalks at stations 7+75 and 20+57 Quorum Drive, please include information in your engineering report that addresses the function operation, safety, signage, markings, visibility of/for both the pedestrians and vehicular traffic including the affects of roadway geometrics and landscaping. This should be supported by an engineering recommendation. In addition, a complete set of plans and bid documents are necessary to complete our review of this 􀁰􀁲􀁯􀁪􀁾􀁣􀁴􀀮􀀠 Please call me if you have any questions or need additional information. J rely, i _ 67JJ.AY/P!//: 􀁾􀀠 􀁊􀁯􀁨􀁾􀀠R. 􀁾􀁡􀁵􀁭􀁧􀁴􀁲􀁴􀁮􀁥􀁲 Director of Public Works JRB/st (214) 450-2871 16801 Westgro...·e PUBLIC WORKS DEPARTMENT December 26, 1995 Mr. Andy Oakley, P.E. Huitt-Zollars, Inc. 3131 McKinney Avenue, Suite 600 Dallas, Texas 75204. Re: Addison Circle -Public Infrastructure Dear Andy: ... The following information is needed to complete the review of the plans for the public infrastructure: 1. Provide three copies of· an updated design report for the rotary. Please remove the language regarding the constrained design or provide an unconstrained design alternative. Please provide sections in the report that address grading, roadway profile, and drainage; and incorporate a full set of plans for the rotary (geometrics, lighting, signage, grading, etc.) with the design report recommendations. This information is necessary for our transportation consultant to complete their review. 2. Provide a design report supported by an engineering recommendation for the use/application for the materials/elements not historically used within Addison. As a minimum, please address operation, safety and serviceability of the material/elements recommended. A. Bricks Please provide information regarding the use of the brick for roadway and sidewalk purposes. Please include elements addressing the function, safety and serviceability of the proposed product. Of particular concern is the use of brick in the valley of the Mews streets and at the valley intersections where runoff/irrigation water mixed with vehicular traffic may subject them to accelerated deterioration or affect their skid resistance. Mr. Andy Oakley December 26, 1995 Page 2 B. Curbless Street/Mews Intersections Please address how this functions. Of particular concern is "the potential for conflict between the pedestrians and vehicular traffic at these intersections and our ability to maintain signage that will not require continual replacement. C. Mid-block Crosswalks on Quorum Drive We have a number of concerns with mid-block crosswalks on streets with 􀁵􀁬􀁴􀁩􀁭􀁾􀁴􀁥􀀠traffic characteristics of Quorum Drive. If you desire the proposed crosswalks at stations 7+75 and 20+57 Quorum Drive, please include information in your engineering report that addresses the function operation, safety, signage, markings, visibility of/for both the pedestrians and vehicular traffic including the affects of roadway geometrics and landscaping. This should be supported by an engineering recommendation. In addition, a complete set of plans and bid documents are necessary to complete our review of this project. Please call me if you have any questions or need additional 􀁩􀁾􀁦􀁯􀁲􀁭􀁡􀁴􀁩􀁯􀁮􀀮􀀠 J Sl.ncJjrely , --1-(2.tCAVATlON 10] """'-􀁅􀁘􀁬􀁓􀁬􀀧􀀮􀁾􀀧􀁏􀁎􀁃􀀮􀀠PAVSMENT JU4 REM. EXlS'!'. roNCo 􀀮􀁾􀁉􀁉􀁬􀁂􀁗ALK lOS 6-LlMI! Sl'AB. SU8GRADE 106/IYDII.'IT!iD UM.I! (l6LBS1SYl 1M S" tISO PSI RIlINF. CONe. PAVe/d1lNT l_ CIRCLE (OI,lm·lI4) OPINIONOF PIIOBAlltg CONSl1.09 7!l6 '" PVCSClI.40Sl.e.liVE t.f SIO 􀁾􀀩􀀮􀀳􀀰􀀠 SI-tB.'l.OO 1fJ1 4W PVC SOl. 40 Sl..8£VE LF 1613 suo S'I.:::RI'so 20!16' PVC SCI!. 40'!£EVE LF m 56_'0 $.l.31S.50 2091IUUGA'TION SYSTEM LS I $7 S88.00 S2J_496.00 31266-CL. III RCP LP 248 SI25.00 S31.OOO.00 313 􀁮􀁾 CL 111 Rep 􀁾􀁦􀀠 1I6 SI45.00 SI6,820.00 ]14 RBM. IiXIST.lNUT 􀁬􀁬􀁾􀀠6' REC.INLET WI REC. TOP EA EA 10 • S450.00 $1.700.00 S4.soo.00 16.800.00 JI6 8' REC. INUIT WI REC. TOP eA 1 $1.800.00 " ......00 JI7 8' REC.lNLBT(8X. DBmtIW/REC. TOP EA I 11.800.00 $1.300.00 318 10' REC.INLETW/REC. TOP EA 2 11.900.00 11.800.00 ]19 10' llEe. INLET 32010' REC.INLET(EX'l1IA OEPTH) .E.A. 1 SJ.700.00 51,900,00 SI.700.00 SJ.IIOO.OO 12112' REC.INLBTW. J,./ltttitt".I•• , ••• tl. •• 12:12:95 ADDISON RaUNOAIOUT 103 tI l l ,ttltlt.I.ltl.tt,.t.,tt*ltltl.tlll!:II., •••III••lt•••tIlfl.II,.,III*••• I •• , ••• *. 1 ,I • E I.) 10.04 7.32 10.06 7.32 * mE PERIOD min 90. 'L' la) 16.43 11.93 16.60 2U3 l liME SllC£ lin 15 * t 􀁾􀀠 (.l UI 4.12 7.01 U2 • RESUlTS PERIOD lin IS IS • • RAG (0) 39.63 1&.29 􀀳􀀶􀀮􀁓􀁾􀀠 45.73 • TlHE CUST D/dn 7.19 * t PHl (d) 􀀲􀀱􀀮􀀰􀁾􀀠 51.00 30.00 21.00 *􀁭􀁾􀀠PERlotl IIn!S 7S • 'DIA (t) 60. '8 60.98 60.'8 60.96 t flOM im pcu/veh VEH I *GMD SEP 0 0 G 0 I FlOli PEU 􀁡􀁾􀁩􀁯􀁰􀁬􀁰􀀬􀀠 PM' * t, *111111••,*llt,llt:t:I&*III*.II.I.I*III'I>IIIIII*III*1'.lltlll*II**III.,III*III' J LEG HAKE IPCU 􀁉􀁦􀁌􀁏􀁾􀁓􀀠 (1st exit 2nd etc.••U)JFLOfICll flO. RATIO IFlDN 􀁔􀁉􀁾􀁾􀁉􀀠 1 * I * il 1 1 IMa QUORUK 11.051 􀀱􀁾􀀠 t099 86 0 11.5It50IO.7j 1.125 0.75'15 45 75 I IWB mmDIU5i 26 219 1I9 0 lUlt5O'O.15 1.125 0.15115 .5 15 • '38 􀁑􀁏􀁏􀁒􀁕􀁾􀀠"I.05t 147 553 149 0 11.31*5010.15 1.1250.75115 .S 75 t IE8 H[lDREOII.OS* 80 219 30l 0 rU115010.15 1.1250.75115 45 15 • l '.J t I. l t • 1 I •• 1 I * I • I 11* I. *11111,••1***1**111,.11'111111111**.,1;11111*:_111*1*1.tl'llllt'II'I"lllllIIII' * I I • fLOW ve'> 16U m I13S 78' • TOTAL O.LAVS • I CAPACITY veb 1987 560 2194 1224 * * t 􀁾􀁖􀀡􀀠 DELAY lins n.26 3.77 0.06 0.15 t 45 hrs • *"AX mAV lins 0.52 7.41 0.08 0.23 1 , • IIYE QUEUE veh 7 40 I? • m pounds * , HAX GU€UE veb 13 76 1 l I • '•. I•••••••••r.*.I., •••••****••••••tl••••, ••I'••'.*••t,'1"""*" ""'t.,*tt,'I" I • • 85 % Confidence Level PM Peak Hour , •••%•••t.II••••; ••I•••••t •••••t •••􀁾􀀮􀀪􀀪•••••I.'I•••••••••••••••••••••••••••••••• * 12:12:'5 ADDISON ROUHDA80UT 104 • f • ••••••••••••,.,.............**. ,.,•••••••••••••••••••••,t••'tttl•••••••••••••••t • * t *E (I) 10.0£ 1.12 10.06 1.32 *IIHE PERIOD lin 90 • , L' (I) 16•• 3 14.93 16.60 2z.1J * TInE SLICE filA 15 • *V (I) 7.01 4.12 UI U2 t R£SUllS PERIOO lin 15 lS • , 􀁒􀁾􀁖􀀠 (I) 39.63 lU9 36.58 45.73 *II"E COST p/.in 7.19 • *PH! (d) 􀀲􀁕􀁾􀀠 57.00 .lM6 27.00 *FlO" PERIGO lin 15 75 t • DIA (e) 60.96 􀀶􀁾􀀮􀀹􀀸􀀠 60.98 60.98 , 􀁆􀁌􀁏􀁾􀀠rYPE 􀁰􀁣􀁵􀁬􀁶􀁥􀁾􀀠 VEN • ,* GRAD m 0 0 0 0 .*FlOM PtA, 􀁡􀁬􀀯􀁯􀁾.􀀯􀁾􀁾􀀠 PM • nu..un.'tuuuJ;lu.'....n.u'.I.nuIUtnu.uunun.u;u••UHIU... • LEG HA"E 'PCU 'FLONS (1ft exit 2nd etc.••U)lrLOFtCl* FIOM RAllO 􀁴􀁆􀁌􀁏􀁾􀀠TIKE' I ,. • *' • I tNS QUORUH '1.05' 701099 8. 􀁾􀀠 '1.11185i o.15 1.1250.15'154575' 'we KILOREOtl.05. 26 279 tl9 0 􀀮􀁬􀀮􀁴􀀱􀀧􀀸􀁓􀁉􀁾􀀮􀀱􀁓� �I.m 0.1S'15 45 1S t IS8 QUDRUM '1.05' W SSJ 169 􀁾􀀠 '1.11'85'0.151.125 0.151.125 0.7S'15 4S 15 t lEa "IL9REO*I.OS' ao 219 303 0 ;1.11*8510.15 1.125 􀁾􀀮􀀷􀁳􀁲􀁉􀀵􀀠45 15 % , * * 1*,. t * * * '#: *.1 :t::t « ttl ft ., t",t"".l"tt••" ••'tI"'lllll,t*.",**tl." ••itC*t1t'*'**"**ltll'II'*"*"" • • •, • rm 􀁖􀁾􀁾􀀠 1556 )26 1011 746 • Tom DELAYS • 􀁴􀁁􀁐􀁾􀁃􀁴􀁲􀀱􀀠 veh 1781 m 1952 Jill t, • *• AVE DELAY sins 0.41 􀀲􀀮􀀹􀁾􀀠 0.01 0.18 42 hrs • IIllX DELAY ains 1.01 􀁾􀀮􀁮􀀠 0.09 0.29 , • , m QUEUE ven 12 30 1 2 t 19) pounds • ,* MAX QUEUE veh 25 􀁾􀀷􀀠 2 5 ,t 1 * , I • ' J:t is not 􀁾􀁉􀁢􀁬􀁥􀀠to est.i1nate q;teUeS an:l delllYS accurately•. 'lbey can only be est.inlat4d for a particular oonfidenca le-oTel (either iJlplicit. or e.lCpUoit). If queues am delays m:e estimated with II. SOl/; confidenc::e leVel. it is 50\ oert:ain that tho actual q>JSI.le5 and delays will hOt be greater than the estimated values. (apart: £taD. randan v.u-iation) '!be delays ard queues ca1rulated dEpend on fla.r and capacity. Jlcth flCM am c::apaoity oontain 'error'. KimbeJ:s capacity eq.mtion has a sttmdard error of -15% to +15% for typical. values. 'l'tl.EI forecast fla.rs _ s.ilnilarly hpnc1se. O::nsequently 1:l1e ratio of fla.r to capacity (RFC) has an even greater stan:\!w:l m:=. 'lbi.1!I wide ra:nr,te of pc:lIi')I!Iihle RFCI s can pt:tldUoe. a very wide :r:al':I;Je of possIble delll,l(S and queues for a given geaoouy. '!be delay/RFC c:urve rFIG. 10) illusU:ates the pt:cble.m. 'llle shape of the cmve is sud:!. that ignormg the nuqe of poss:U!.le RfC's can lead to a 9l:O$S UI'IdeJ:est.il1tion of the 􀁰􀁯􀁳􀁳􀁩􀁢􀁬􀁾􀀠qualI!:S and delays. 16 14 12 10 4 12 􀁯􀁾􀁾􀀮􀀽􀀽􀁾􀁾􀀽􀀽􀀻􀀽� �􀀫􀀬􀀽􀀽􀁾􀀮􀁾􀀺􀀺􀁾􀁾.....􀁾􀁾􀁾􀀠 l 0-2 0'4 I 0'6 l 0<11 1-0 I 1-2 .--------... ...--------.J Case 1 Cua2 FLOW/CAPACITY FIG. 10 !mAY I RFC In case 1 the whole RFC 􀁾 is on the flat part: of the curve, en::lany value of RFC in the range will prcduoe 1CM delays. 'lhe delay :fQre(;:ast 1eI t:he;tefore 􀁾􀀮􀀠 ' ' C'ase 2 is quite different. 'lhe 􀁾 RFC (SOIa 􀁣􀀺􀁣􀁮􀁴􀁾􀀠level.) has l3elays virblally the same as Case 1. HowI!!IYer, as cue 2 .is close to the steGp 􀁾􀁯􀁮 of the cw:ve, the possible values of RFC greater than the 50\ value 35 have Vfir'J high delays. Values greater than 50% will 00::I.1I:' if .tba aet:ual flows are graater than tba inplt flQWl1l, arteVor if tho actual capacH:;y is lower than the theo1::etical. 1IilCN1i bpl1cl.tly uses tba 50% cxmf1.c1enoe level by \lain; the av....<:qiI value for capacity with tba irJp.rt: flews. case:3 'WOOld 􀁾􀁲􀀧􀁡􀁣􀀺􀁣􀁥􀀬􀁰􀁴􀁡􀁢􀁬􀀮􀁥􀀠 to the Design &'qineer with a 50% cxmfiden:e 1evel. 'lbere 'WOOl.d therefore be no ir1centi_ to m::dify the geanetry in order to i.nc::n:'ease the capacity. 1lny .increase wooJ.d prodIloe no significant reducI::icn in the calculated delays sinCe the average RFC is on the flat part of the cu:rve•. The design would therefore be oonsiClE!ted acceptable, am the risk of very high delays not realised. With ROt:lEL the cxmfidence laval is irJp.rt: explicitly. 'Ihe queues ani delays can be quickly fwni for various cxnfidence levels. (ie 50% to 99%) A l.lIini:J!ium oanfidenoe level of 85% is des.i:J:1ea1:lle • • KJDEL at 85% 'WOOld indicate that case 1 _ acceptable. HoWever, the delays at 85% for case 2 wooJ.d be Vt¥r'/large, ptt;7Viding a d'IIJl1en;Je for the d.E!Signllllr. The good news is that sin::le the 85% RFC is on the steep part of the cu:rve it is exlzemely senstive to -U 􀁾 in RFC (dlan3es in capacity an:'Vor 􀁦􀀱􀁾􀀩􀀮􀀠 '!be geawatzy therefom icKinfl#)! 􀁁􀁾􀁟􀀠• Su. 6(J(J • DtllliIs. T....u 75204 •. aU} 8il·JJ]1 • FA..'!' (214) 8il.()757 HUllT-LOLlARS E"....... '_.. 3Jll 􀀢􀀧􀁾􀀢.... -... 5... 600. 110Iloo. 1_7f.104 _ t2!c,I7I-33lI' Fa" (211) 􀁾􀀷􀁓􀀷􀀠 I ANDREW C, 0NtIEf. P.f. Slftllll''\I'a 'ntMlnt ....􀁾􀀮􀁨􀁦􀀱...=..."........... ........................................................................................................................................................ ... ,.,.......... 􀁊􀀳􀁲􀁾􀁉􀀳􀀮􀂫􀁴􀀺..NA.il. 4!;J;oJ.... 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I... 101), !lob,T_1S204 ",-,,., \21<1)171.,13111 F.. (Il')67l- David E. Meyers, P.E. cc: Bryant Nail, Post Properties, Inc. Mike Robbins, Post Properties, Inc. John Baumgartner, Town ofAddison H:\PROJi01182221\GE110891.L1R Dallas JFort Worth I Houston I SI Paso (Phoenix I Orange County HU[Tr-ZOLlARS Dallas • Fort Worth • HOfIStGn • El Paso • Phoenbi: • Tustin • Ontario • Albuquerque FACSIMILE TRANSMITTAL Date: II /10/t7 Fax No.: 􀁾 B.QJI." H-Z Proj. No._______ No. ofPages:._=:3:::--:-__ (Including Cover Sheet) ... 􀁾􀀱􀀿􀀠 -g"72-cSu,lP -(,S'O o URGENT )G'ForYourReview o Please Call Upon Receipt )torig. To Follow By Mail SENTBy:_____________ TIME:,___ DATE:___--:___ .131 Md1nm!yA-. .Su/tJt(f(}(}.DaIku. T= 7521J4..2489. (214) 871-5511 oFAX(2U) 871.(1757 ( " Project AddiPC\n.\1. % HLlITT Job No.OI Zpl3". Date ,,,,192 Client "lhWI\IIot' 􀁾􀀠ZOlARS By Pi"'-, Task \&11't1En. Arg, IIICQAPQAA1EO Chkd Date___ 􀁾􀀢􀀮􀀶􀀠Ac,Id,-li'D-\.. Sheet I 􀁯􀁲􀁾􀀢􀀧􀀲􀀮􀀮􀀮􀀽􀀭􀀭􀁟􀀠 ® LII'€. t., Po-.v. 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I -FIRE HYDRANT CONCRETE BLOCKING LJ 􀁁􀁄􀁄􀁉􀁓􀁏􀁾􀀠 Huitt-Zollars, Jnc {3131 McKinney Avenue I Suite 600 I LB 1051 Dallas, Texas 75204-2489/2141671·33111 FAX 214/871-0757 November 18, 1996 Mr. John Baumgartner, P.E. Public Works Director Town ofAddison p.o. Box 144 16801 Westgrove Addison, TX 75001 RE: Addison Circle Phase I Public Infrastructure Sight Visibility Modem Roundabout HZl Project No. 0 I -I 822-04 Dear John: As requested, we have asked our roundabout 􀁣􀁯􀁮􀁳􀁵􀁬􀁴􀁡􀁮􀁾􀀠Peter Doctors, to review the roundabout with respect to the current placement ofbuildings in Phase I and the proposed placement of buildings in Phase II of Addison Circle. Per the enclosed letter and sketch, Ourston and Doctors has concluded that the placement of a building on the right-of-way line does not violate sight requirements. At the same time we asked Ourston and Doctors to review the other proposed elements within the roundabout for compliance with visibility requirements. Peter provided us with a sketch which indicates the zones that are to be kept clear below 6 inches and 25 inches. After reviewing the guidelines for visibility and transferring the sight triangles to our plans we believe that some small modifications are prudent. The inside row of tree pits nearest the curb in the roundabout currently includes under-planting of Dwarf Yaupon Hollies. The Yaupons violate the not greater than 6" triangles at four locations. From an aesthetic perspective, the landscape architect has recommended that all hollies in the roundabout be deleted and replaced with groundcover as opposed to partial deletion of the hollies. It is our opinion that the 12" high tree fence is not an obstruction in the 6" triangle because of the gap in the fence, therefore, they will remain as designed. The 35" high sight triangle is not a factor since the hollies are being replaced with ground cover. All red oaks will be planted around the circle as planned since they are no more imposing than obstructions such as light posts and bridge columns which are allowed in the sight triangles, The letter also states that no landscaping greater than 35" is allowed in the center medians on the approach roadways, A review of the roundabout design guide states that higher elements are allowed such as light poles, bridge columns or sign posts, As stated above, we believe that the planned red oaks are less imposing than a bridge column and therefore may be planted in the center islands as designed, O;\PROFIOllm04\1BJI07LTR Dalias I Fort Worth /Houston I EI Paso I Phoemx 1Tustin I Onlano /San Clemente In addition, we have reviewed the questions and comments in your letter dated October 28, 1996 which transmitted a copy of the 1986 Australian manual on roundabouts. In general, this manual is somewhat dated because so much has been learned about the design and operation of modern roundabouts with their proliferation over the last 10 years. However, there is nothing specifically outdated about Table 2.1 and as the table suggests, the choice ofa roundabout at Addison Circle was made on a site-specific basis by experts in the field. Figure 4.7 is not particularly detailed in its criteria and Ourston & Doctors have applied more detailed criteria for visibility using the figures enclosed. Chapter 8 seems to be written from a rural highway perspective (mountable curb? no trees near roadway?) placing all of its emphasis on the vehicle and none on the pedestrian experience (or safety). While its overall message ofcare to preserve visibility in the design is valid, its examples do not seem appropriate given the location and conditions of the Addison Circle Roundabout. Please call ifyou have any questions. Sincerely, HUITT-ZOLLARS, INC. Andrew C. Oakley, P.E. Senior Vice President ACO/psp Enclosure cc: Bryant Nail -Columbus Realty Trust Paul Shaw-Newman, Jackson & Bieberstein G:\PROllOlI82204\JB IlO7.LTR 􀁾 Ourston & Doctors I MODERN ROUNDABOUT INTERCHANGES November 6, 1996 Mr. Andrew C. Oakley, P.E. Huitt-Zollars, Inc. 3131 McKinney Avenue Dallas, Texas 75204-2416 SIGHT DISTANCE ANALYSIS Pursuant to your request, we have completed a sight distance analysis for the areas adjacent to the roundabout to determine if a building facia can be within 30 feet of the inscribed circle diameter (lCD). Indicated on the attached diagram are areas of landscaping of less than 35 inches and 6 inches. In addition to these slivers of limited height obstructions, the splitter islands must not have any landscaping greater than 35 inches. We see no reason why a building could not be at the proposed location on the south east corner. Attached to this report are the sight distance requirements set forth in Roundabout Design Guidelines, Ourston & Doctors, 1995. These requirements are derived from British manuals on roundabout design which we have used in all our designs. The sight distance requirements referenced by John R. Baumgartner, P.E. are not current with British practice. The British have studied this "sight triangle" approach to sight distance and found that the increase in sight distance has a negative effect on safety. Excessive visibility at entry only promotes higher entry speeds. We have seen at least one case of this here in California. Very truly yours, ctJ Peter Doctors, P.E. 5290 Overpass Road, Suite 212 Santa Barbara, CA 93111 805/683·1383 http://www.west.netl-owendee Fax: 805/681-1135 less than 6" : .. 􀁾􀁾􀁾􀀠•• 􀁾􀀠•• J'•••• ' lass than MILDRE.DSi 􀁾􀀠..... . .,....""'-:,:..... .. . . . . '. .' ' . ........ : .' '" .. .'" lass than 6..􀁾􀂷􀂷.... ' . .... .... .. . ... . . . . . . . ' .. .. . , '. .' " ... . ." ...... , .. .' : less than 35" y... .􀁾􀀠..:... ' .. . ..... .; ....􀁾􀀧.... . lass than 6" ; ; 􀁾􀀠 -N: : : ! . .-9:: <:::I . gf . : is: Scale: 1"=50' : : : Ourston &Doctors Site Distance Evaluation MODERN ROUNDABOUT INTERCHANGES Addison Roundabout 5290 Overpass Road #212 Santa Barbara, CA93111 11/05196 ! ROUNDABOUT DESIGN GUIDELINES Chapter 7 Page 36 Geometric Design Features Figure 7120b Vertical Visibility Envelope, All Other Visibility Object Bottoms of Sign Panels Driver's Eye 2.Om 177-7-/-;'7""7"Cr7-T,..."...."...,....,'""7"T 2.Om (6.6') 1.05m 0.26m 􀁂􀁾􀀲􀀺􀁵􀁾􀁾􀁾􀁾􀀭􀀺􀁊􀀧􀁬􀀠(3.4') (0.85') Signs in these areas should be mounted not less than 2.0 meters above the roadway surface. The envelope should be checked on site if there are changes in gradient. Visibility to the Left Drivers of all vehicles approaching the yield line should be able to see the full width of the circulatory roadway to their left, from the yield line for a distance appropriate to the stopping sight distance for circulating traffic, measured along the centerline of the circulatory roadway, as indicated in Table 7!2. Table 7/2 Roundabout Visibility Inscribed Circle Diameter Sight Disiance I (Meters) (Feet) (Meters) (Feet) <40 <131 Wholelnt. Whole lnt 40-60 131-197 40 131 60-100 197-328 50 164>100 >328 70 230 This sight distance should be checked from the center of the left lane at a distance of 15 meters (49 feet) back from the yield line, as shown in Figure 7 noc. Checks should be made that poor crossfall design or construction and sign location do not restrict visibility. Figure 7/20c Visibility to the Left Required at Entry --1 LEGEND a b e Sight distance related to Circulatory speed, as given in Table 7/2. Sight line. Half-lane width. Area of Circulatory roadway over which visibility should be obtained from viewpoint 0:: C ••• •••,• •••••••••• •••• /---􀁾􀀠....•......• ....; ...........,.. 1 {J/i ADDISON CIRCLE ROUNDABOUT •: SIGHT DISTANCE EVALUATION •: 11/07/96 ••••• •• •• HUITT-ZOLLARS. INC. More than a home .... It's a new hometown. Gaylord Properties, Inc. REALTY TRUST We cordially invite you to attend the groundbreaking ceremony of Addison Circle Intersection of Mildred Street and Quorum Drive Addison, Texas Monday, January 8,1996,12:30 p.m. Reception immediately following ceremony Addison Conference and Theatre Centre Please RSVP. by December 29 to 770·5566 BEGA Pendant mounted tuminaires with wide beam, round symmetrical light distribution. Die cast a!uminum "heat sink-housingl 8 ballast compartment Specular anodized aluminum reflector with I matte dear anodized outer finish. r \ Clear tempered glass enclosure. Color: Black with natural aluminum. Custom colors can be supplled on special oldeL A Lamp Lumen A 8 ( " ',-i 8174S 1 100W E17 HPS 9500 15 2OY16 8"""1"·7_M4_M····H____ 1 100W ED'17 MH 8500 15 2OVI6 817SP 5 26W PLC 9000 20'/4 26 ..._-8175S 1 2501'1 E·28 HPS 28000 20% 26 8175MH 1 250W ED'28 Mr! 22000 20% 26 ------.... Pendant mounted luminaires with wide beam, round symmetrical light distribution, Die cast aluminum housing/ballast compartment with additional top light output. Die cast aluminum gua(d wiLh white louver stack A inside clear crystal glass with vertical slructUJ'e. Clear polycarbonate plastic available. -suffix PO. Color: Black with fnside of reflector painted v.hite. Custom colors can be supplied on special order, ; Lumen A B 'j 81766 SOW E·17 HPS 4000 17J1, 8176MH 1 100'11 ED·17 MH 8500 21% 17% .......... ... 􀁾􀀭 Luminaires for Cable or Stem Suspension 3 HUITT-ZOLlARS HuiU-ZoilarS, Inc /Engineering JArchtlecture /3131 McKinney Avenue I SuilE! 600 /La 105/Dallas, Texas 􀀷􀀵􀀲􀀰􀀴􀁾􀀲􀀴􀀱􀀶􀀯􀀲􀀱􀀴􀂷􀀸􀀷􀀱􀀮􀀮􀁳􀀳􀀱􀀱􀀱􀀠FAX 214-871..(J757 December 12, 1995 Mr. John R. Baumgartner, P.E. Director of Public Works Town of Addison 16801 Westgrove Drive Addison, Texas 75001 Re: Addison Circle Phase I Huitt-Zollars Project No. 01-1822-04 Dear John: Pursuant to our telephone conversation this morning, I would like to update you on our progress regarding resolution of issues on the project. As I mentioned when we spoke, my primary focus is on the seven items that were specifically noted as not approved along with the Development Plan when it was tabled at the City Council meeting of November 28th. It is my goal to assure the Council that these issues are being addressed and will be resolved to the complete satisfaction of the City Staff prior to a full building permit being issued. We fully understand that Council approval of the Development Plan is subject to future future resolution of these items but are hopeful that such an approval can be received tonight. I. Streetscape plans. We believe our final construction plans will address all of your concerns about pedestrian and vehicular conflicts. Those plans will be complete this week. 2. Paving plan for mews street. We have still not resolved the best way to intersect the mews with the other streets but are committed to arriving at a design that both the developer and the Town will be happy with. Final plans will reflect the latest input on this issue from all parties as well as your comments on the pavement itself. 3. Security gates and control devices will be detailed by the architects in their permit set to be submitted this week. 4. Landscape Architectural contract documents for the public work will be complete by early next week. We understand that Newman, Jackson, Bieberstein is meeting with Slade Strickland as the design develops to be sure that his goals are being met. 5. The master street plan for the district district is a combination of the concept plan and the typical G:\PROJ\{)1182204VB1212.L1R Dallas f rort Wonh I Houston I EI Paso I Phoenix I Orange County Mr. John Baumgartner December 12, 1995 Page 2 street sections in the ordinance. The [mal concept plan should reflect resolution of deadend streets and other concerns you have expressed. It this is not the case, please let us know specifically what you would like to see and we will prepare it. 6. The Master Drainage and Utility plans for the District have been revised per your latest comments and will be transmitted with the [mal plans this week. We have removed all references to "by others". 7. The [mal (Physical) design for the roundabout is included in the construction plans. The support for this design is contained in the study which was previously submitted. Our response to some of the comments on the study are enclosed herein, however, Peter Doctors will not have the information on the revised level of service until later today or tomorrow. I know that as of our plan review meeting of November 21st there seemed to be a great many items yet to be addressed. However, I did not then, and do not now, feel that we are in disagreement on the resolution of many, if any, of those items. This is a very complex project for which the standards are being developed at the same time as the final design and we are therefore taking a lot of time to be sure that the appropriate standard is established in Phase I for the remainder of the district. When we met on November 21st, the plans consisted of 66 sheets. They have expanded to over 120 sheets for additional clarity and detail yet we have still not completely addressed every issue. We are, however, committed to doing so and are confident that you will be pleased with the results. Toward that end, I am enclosing draft copies of the responses to your various review memos and other comments that will, in their [mal form, accompany the plans for your review later this week. I offer these at this time, even though they are incomplete, as an indication of our continued work and progress toward full resolution of all issues. Sincerely, HUITT -ZOLLARS, INC. Engineering! Architecture ACO/psp cc: Bryant Nail -Columbus Realty Trust Carmen Moran -Town of Addison Go\PROJ\01182204I1B1212.LTR DRAFT ADDISON CIRCLE RESPONSE TO CITY REVIEW COMMENTS IN MEMO DATED SEPTEMBER 5, 1995 FROM JOHN BAUMGARTNER 1. Utility and Drainage: A. A water and sanitary sewer study prepared by a professional engineer is necessary to verifY the adequacy of the proposed system. This study shall include all property included in the approved concept plan and its respective drainage basin. The water and sanitary sewer study has been prepared and reviewed by City StaffSee separate response to review conunents. B. A storm-water study prepared by a projessional engineer is necessary to verifY the adequacy of the system. As a minimum this study shall include all property included in the approved concept plan and its respective drainage basins. The stOnTI-water study has been prepared and reviewed by City Staff -See separate response to review conunents. C. Storm drainage system shall be extended to provide for the properties north and west ofthe proposed development The design engineers shall demonstrate that the downstream system has sufficient capacity for the lOO-year storm event or provide storm water detention. Done and addressed in study. D. The sanitary sewer shall be extended to provide service to the properties north and west ofthe proposed development. Done and addressed in study. E. No residential water, irrigation, or fire sprinkler service is available from the transmission mains in Quorum and Mildred. Acknowledged -Plans reflect this limitation. F. A sewer line extension is necessary to provide service to the properties on the northwest and southwest corners ofMildred and Quorum. Done and reflected on plans. G. The actual location within the road right-ol-way of the various utilities will be determined at the time of development. These locations must provide for the installation ofprivate utilities (electric, gas, telephone, fiber, television, etc ... ) with franchise or license agreements. G:\PROJ\O 1182204\MEMORESP.ACO 1 IruITT-ZOLLARS, INC. -12112195 DRAFT Acknowledged and reflected on plans. H Additional utility and storm drainage easements are required. Shown on Plat and Plans. 1. What happens with the storm drainage east of the rotary? Does it cif.foct the existing residence on the northwest corner ofthe tollway and railroad? There is no effect on the existing residence. 2. Quorum Drive: A. A design report should be provided that details the appropriate roadway geometries, traffic control, markings, signage and parking for the proposed rotary prior to finalizing the lot layout. See the attached review provided by Barton Aschman. Plans now indicate all elements of the roundabout necessary for its construction and operation as dictated by the study. B. The street section should be revised to reflect the minimum roadway dimensions indicated in the ordinance which provides for two 11 foot lanes and an 8 foot parking lane from face ofcurb to face ofcurb, Done and reflected on Plans. C. Quorum Drive is currently identified as a major arterial on the thoroughfare plan. The developer should provide evidence from his traffic consultants to verifY the proposed revision to the plan. The changes to Quorum Drive do not preclude its use as a major arterial and our plans neither contemplate nor address such a revision to the thoroughfare plan. The level of service provided by the introduction of the roundabout is consistent with arterial operation. D. The additional right-aI-way required for Quorum Drive corridor should be dedicated with Phase I from the railroad to the northern district boundary, Because this development is the first phase ofa multi-phase project, this corridor is necessary for utilities and possible roadway expansion. Due to the complex arrangements of the partnership between Gaylord and Columbus, the dedication of all right-of-way for Quorum Drive at this time is not possible. However, the dedication of easements for utility, landscape, sidewalk and related purposes over the future R.O.W. area is possible and has been reflected on the fmal plat and and plans. G:\I'ROJlOllll2204\MEMORESP.ACO 2 HUITT-ZOLLARS, INC. -12/12/95 DRAFT E. Ingress, egress, and parking shall be situated so they do not interfere with the operation ofthe rotary. Additional design information is required to determine the appropriate location. Done -Refer to Ronndabout Study and Final Design. 3. Residential: A. All streets shall be designated by a name or number. Done and reflected on Plat and Plans (Currently as numbers-names are pending). B. Ifsome ofthe property accessing the proposed streets is not residential, alternative cross sections are required All property accessing the residential streets in Phase I is residential with the exception ofsome gronnd floor retail near Quorum Drive which was contemplated by the ordinance. No office buildings or other major deviations exist. C. With the exception of the double parking where people were moving into apartments and the parking in the neck-down areas, we were comfortable with the residential street widths of 37 feet from back ofcurb to back ofcurb with neckdown areas at intersections being 23 feet (back back to back). However, this assumes the appropriate radius isprovided for emergency/service vehicles and street lights, furniture, trees, etc., are set back sufficiently to avoid any conflicts with turning vehicles and visibility at the intersections. 35' visibility triangles and 30' radii provided have been coordinated with City fire officials. D. Where the residential streets dead-end, provisions should be made to provide a vehicular turnaround until the roadway are continued Done and shown on plans for Phase I and Concept Plan for future phases. 4. Mew's: A. Ifthe mew's are going to be dedicated as public streets then a standard curb and gutter section is recommended to control traffic and drainage. As a compromise, a section with a roll up curb may be acceptable. See Below B. The current cross-section proposed in the preliminary constructions plans does nat match the concept plan cross-section. Has this changed? Please revise as necessary. G:\FROJ\Oll81204\MEMORESP.ACO 3 HUITT-ZOLLARS, INC. -12112195 DRAFf The inverted, curbless section for the mews has now been recommended for approval by staff and P & Z. The final plans reflect this cross-section. (See further discussion under later comments). Council action is pending. 5. Mildred: A. The approved concept plan does not reflect a reduction in Mildred's cross-section to approximately 60 feet. This reduction appears inconsistent with the current use of the street and will limit our ability to add additional parking or lanes if the demand warrants at the approach to the rotary. The 61' (B-B) section for Mildred has now been recommended for approval by staff and P & Z. Council action is pending. B. If the reduced cross-section is approved, the relocation of the existing 24" waterline is required The 24-inch waterline is being relocated. C. Ingress, egress and parking atijacent to the rotary shall be located so that they do not interfere with the operation of the rotary. Additional design information is required to determine the appropriate location. Refer to Roundabout Study and Final Design. 6. Alternate material for brick accents bands, crosswalks, sidewalks, streets, etc ... , should be considered In the past, the Town has iiUccessfitlly used patterned concrete or pave stone (placed on a concrete base) to give an appearance of brick with more durability, serviceability, and less susceptibility to settlement. It has been the developer's and the designer's opinion that certain materials, such as brick and granite cobbles, impart a more established feel to the urban environment that helps keep the project from looking so new and "manufactured". Pavestone-type products are not as compatible with the intended feel of this district and patterned concrete has its own set of maintenance and durability problems. Therefore, the chosen accent paver material is (clay) brick, with different ratings for pedestrian and vehicular applications. 7. Vehicular visibility shauld be provided for all streets, mews and driveway approaches/intersections. The required 35' visibility triangles have been honored at all public street intersections, including the mews. As we have discussed, garage exits with limited visibility onto the streets is a common urban issue and will be dealt with in the architectural plans using signage, gates, lights, mirrors and other typical mechanisms for pedestrian safety. G;\PROMll 82204\MEMORESP.ACO 4 HUITT-ZOLLARS, INC. -12/12/95 DRAFT 8. Miscellaneous Plat: A. Lot 1 Block "B" does not meet the minimum lot width of200 feet required in the concept plan ordinance. Variance recommended by P & Z. Council action is pending. B. Additional right-ol-way is required to provide sufficient sidewalk width at the street-street and street-mew intersections. Based on the final design, the only location that additional width may be required is at the southwest comer of Mildred and Quorum on the Town's (future) property. 9. Private Utilities: A. Provide details regarding the location and access to the TUfacilities serving the district. Complete construction plans for the T.V. Electric facilities to serve Phase I of the district are included in our submittal. B. Provide sign-of! from private utilities to approval ofeasements and cross-sections for the district. Letters we have received from the franchised utility companies concerning their need for facilities within the district are enclosed. Note, however, that telephone and CATV service throughout the district will be handled by a secondary provider who will install his own duct system under license agreement. 10. Preliminary Construction Plans: A. Provide additional information from rotary consultant regarding markings, parking, signage, transitions associated with the Quorum/Mildred intersection. Refer to Roundabout Study and Final Design. B. Provide details and design information regarding brickslpavers being considered for use in the public open space. Ofparticular concern is the hardness, durability andfriction provided by the proposed material. This repart shall be prepared by a professional engineer and submitted to our design consultants for review and recommendation. Test results on the pedestrian brick are enclosed for your review. Test results on the vehicular brick are pending. G:'lPROJ\G118.2204\MEMORESP.A CO 5 HUITT-ZOLLARS, INC. -12/12/95 DRAFT C. Additional material submittals may be required prior to bidding for review of street lights, fUrniture, etc ... Catalog cuts and other details are enclosed herein or included in the plans for the following streetscape elements. Benches Street Lights Trash Cans Tree Grates Tree Fences Bollards D. Pavement marking/signage plan is required for the roadway and parking areas. Pavement markings and signage are shown on the fmal plans as follows: Signs are indicated individually Striping is indicated by typical detail E. Sidewalk eyebrows are required at the intersection ofthe mews with Mildred and the residential streets. This provides protection of the site visibility areas and turning radii for commercial and emergency vehicles. Raised neckdowns (or sidewalk eyebrows) have not been used because they negatively impact the street hierarchy that the urban designers are trying to establish. However, a brick pattern flush with the driving lanes which delineates the clear zone, coupled with a "No Parking" sign on each side of the intersection is proposed. F. Site visibility areas shall be protected from encroachment at all intersections and driveways. The minimum requirement calls for a 35' visibility triangle in some cases additional protection may be necessary. This requires revision to the proposed buildings and the starting location ofthe parking. Done and reflected on plans. (Note: Showing the visibility triangles on every intersection cluttered up the plans and is of no use to the Contractor so the lines have been deleted). G. Provide details regarding loading and unloading of deliveries for commercial property, household fornishings, etc... The current preliminary plans do not seem to provide for these elements. Final plans reflect areas to be marked as loading zones. H Our current ordinance requires hydrant spacing of300 feet in retail/commercial areas and 500 feet in residential areas. Hydrant spacing and location requires the G,IPROJlOIIB2204IMEMORESP.ACO 6 HUITT-ZOLLARS, INC. -12112/95 DRAFT approval of both the Fire Department and Public Works Department. Our general approach to the urban center district is that all of the property is commercial for the purposes of fire coverage and similar issues. Though we refer to "residential" streets, these are not residential in the traditional sense. Therefore, our goal is to achieve approximately 300 foot fire hydrant spacing. However, the block lengths are such that the usual positioning of fire hydrants at intersections results in some cases of slightly over 300 foot spacing. Considering the fact that all structures are sprinklered, we felt it would be excessive to add mid-block fir hydrants. We can do so if the fire marshall believes it is necessary. 1. The proposed plans seem to encumber property owned by others to provide service to this district. Particularly Building "Bn and the provisions for TU Electric and drainage. The encumbrance to City property for transformer access to building B has been eliminated. The storm sewer line west of building B serves primarily to collect the runoff from the City property and is located to provide for your future use without physically encumbering other uses of the property. Easements are indicated as required. J. Are the plans for the public space enhancement within the rotary consistent with the existing and proposed utilities? All existing and proposed utilities have been routed around the central island of the roundabout except the 24-inch waterline. If the waterline must be moved to accommodate the central feature, the plans can be modified. K. What are the plans for trash collection? The procedures for trash collection have been described in separate correspondence to your environmental official. Our plans reflect thickened pavement in the areas adjacent to the compactors as requested. L. Drainage from the buildings and mews shall be collected prior to entering the streets. A complete system of downspouts and private collection pipes is proposed in the "onsite" civil drawings to capture roof drainage. Without this contribution of runoff from the buildings, the mews generate between 0.7 & 2.5 cfs of runoff in a 100 year event. We did not feel that these flows justified the addition of 4 inlets and pipes at the four entrances to the mews, however, they can be added if you prefer. M A more detailed utility plan is required. Done and included in plans. G,IPROJ\OI182204IMEMORIlSP,A CO 7 HUITT-ZOLLARS, INC. -12/12/95 DRAFT N. The minimum curb return radii for fire vehicles is 30 feet. Variances to this requirement are approved by the Fire Department. All curb radii (or theoretical turning radii where no continuous curb exists) have been increased to 30 feet. 0. It is necessary to recess the inlets in the parking areas to prevent encroachment of the parking in the traffic lanes. The primary purposes of recessed inlets are the increase in capture that they allow and the area they provide outside the driving lane for the concentrated depth of flow. They are a suburban thoroughfare-type detail and are not used in highly urbanized areas, particularly with parallel parking and significant pedestrian activity. whether the inlets are recessed or not will not affect how cars are parked. We believe that recessed inlets in this environment are a hazard to pedestrians and those that are getting out ofvehicles. We therefore recommend and have designed standard curb inlets throughout Phase I, except along the portions of Quorum Drive Drive where there is no parallel parking. P. The minimum throat width for the residential streets shall be 23 flet back to back Shown on plans. Q. It was our understanding that significant portions ofthe mews is going to have a brick overlay. In addition, some areas of the residential streets Mildred and Quorum were going to be brick enhancements. Has this changed? The mews have substantial areas of brick while the remaining streets have only brick crosswalks and sidewalks. R. The cross-sections do not seem to provide for all licensed utilities and any additional private utilities (i.e., private electric, cable and communications between buildings 􀀧􀁾􀀢 and "B',. What is the status ofadditional private utilities? A sleeving plan for private utilities will be included in the onsite civil plans and its installation will be coordinated with the public contractor. (License agreements are being handled by Columbus' attorney). S. Turn lane on Quorum requires 150 feet ofstorage, 150 feet of transition and a width width of11 feet. Done and shown on plans. T. What is the status ofthe landscaping, irrigation and street treatment plans? Full streetscape plans are included in this submittal. Planting and irrigation plans are nearing completion and \'I'ill be submitted for Slade Strickland's review on O;\PROJ\OlI82204IMEMORESP.ACO 8 HUITT-ZOLLARS, INC. -12/12/95 DRAFT December 18th. U. Additional drainage information is required to verify inlet/line locations and sizes. Done V. Inlets are required uphill from the intersection of Quorum and Mildred to eliminate stormwater runoff in the rotary. Done W. What are the plans for Mildred east ofQuorum? Would it be advisable to add to the rotary during the next phase rather than installing barricades today? Plans have been changed to reflect a closed rotary to the east so that no barricades will be required. X Fire hydrants and gate valves are required at the end ofall water lines. Done Y Insufficient vehicular visibility is provided at all garage motor court entrances and several street intersections. See response to #7. Z Retail use and driveway access may not be consistent with the existing or proposed use ofMildred Street. This is an issue that will be addressed on the development plan. No Comment AA. The boiler plate construction contract requires the review of our City Attorney. Ofparticular concern are issues regarding the assignment of the agreement to Columbus insurance coverage, additional insured's, etc ... Acknowledged BB. The sidewalk pavers/bricks shall have a concrete base. This is not provided for in the current cross-sections. All sidewalks are now shown with a concrete base. Cc. Additional water valves are necessary to provide for proper isolation in the event ofa line break Done G;\PROJlOI18221l4IMEMORESP.ACO 9 HUITT-ZOLLARS, INC. -12/12/95 DRAFT DD. Provide street lighting plans. Show the proposed location oflights, transformers and switch gear. Street lights are shown on the streetscape plans. Switchgears and transfonners are shown on the electrical duct plans. The connection between the street light runs and the transfonners is dependent upon T.V. Electric's proposed circuitry which has not yet been developed. (T.V. also needs to comment on the handhole locations and other aspects of the conduit routing). We have not asked T.V. to perfonn this design work yet because of the possibility that the system will be owned by the City. 11. Additional review is necessary upon submittal of the required information. Acknowledged G:\PROJ\t)11&2204\MEMORESP.ACO 10 HUITT-ZOLLARS, INC. -12112195 DRAFT ADDISON CIRCLE RESPONSE TO CITY REVIEW COMMENTS IN MEMO DATED OCTOBER 16,1995 FROM JOHN BAUMGARTNER 1. Utilities and Drainage: A. The master utility and drainage reports require refinement and resubmittal. Comments sent to Huitt-Zollars under separate cover on 10111195. Done -See separate response to those comments. B. Storm drainage system shall be extended to provide for the properties north and west of the proposed development. The design engineers shall demonstrate that the downstream system has sufficient capacity for the 100-year storm event or provide storm water detention. Done C. No residential water, irrigation or fire sprinkler service is available from the transmission mains in Quorum and Mildred. Acknowledged D. A sewer line extension is necessary to provide service to the properties on the northwest and southwest corners ofMildred and Quorum. Done and shown on plans. E. The actual location within the road right-ai-way of the various utilities will be determined at the time of development. These locations must provide for the installation ofprivate utilities (electric, gas, telephone,fiber, television, etc ... ) with franchise or license agreements. Acknowledged F. Additional utility and storm drainage easements are required. Shown on plat and plans. G. What happens with the storm drainage east of the rotary? Does it affect the existing residence on the northwest corner ofthe tollway and railroad? No effect. H All dead-end wastewater lines shall have clean outs or manholes and all dead-end water lines shall have fire hydrants. G:\l'ROl\Ollll2204IMEMORESP.ACO I HUITT-ZOLLARS, INC. -12/12/95 DRAFT Done I Storm sewer inlet is proposed on property used for Town's water tower. This will encumber this property and requires approval by the Town. See comment #101 on September 5th memo. Tbis item was recommended for acceptance by P & Z at their November 21st meeting subject to staff approval of fmal plans. 2. Quorum Drive: A. A design report should be provided that details the appropriate roadway geometric, traffic control, markings, signage, lighting and parking for the proposed rotary prior to finalizing the lot layout. See review provided by Barton Aschman. Report has been submitted and reviewed. See separate response to comments and fmal design. B. The street section should be revised to refiect the minimum roadway dimensions indicated in the ordinance which provides for two 11 foot lanes and an 8 foot parking lane from face ofcurb to face ofcurb. Done C. Quorum Drive is currently identified as a major arterial on the thoroughfare plan. The developer should provide evidence from his traffic consultants to verify the proposed revision to the plan. See Item #2C on September 5th memo. D. The additional right-ol-way required for Quorum Drive corridor should be dedicated with Phase I from the railroad to the northern district boundary. Because this development is the first phase ofa multi-phase project, this corridor is necessary for utilities and possible roadway expansion. See Item #2D on September 5th memo. E. Ingress, egress and parking shall be situated so they do not interfere with the operation qfthe rotary. Additional design information is required to determine the appropriate location. See Item #2E on September 5th memo. F Turn lane should include a transition of 150 feet with 150 feet ofstorage. Done and shown on plans. G:\PROJ\OI182204\MEMORESP.ACO 2 HUITT-ZOLLARS, INC. -12112/95 DRAFT 3. Residential: A. All streets shall be designated by a name or number. There are different designations for each street that appear throughout the plans. There may be a need to go back to the development plan and concept plan and add the street names when they are selected. B. Ifsome ofthe property accessing the proposed streets is not residential, alternative cross sections are required See Item #3B on September 5th memo. C. With the exception of the double parking where people were moving into apartments and the parking in the neck-down areas, we were comfortable with the residential street widths of 37 feet from back of curb to back of curb with neckdown areas at intersections being 23 feet (back to back). However, this assumes the appropriate radius is provided for emergency/service vehicles and street lights, fUrniture, trees, etc., are set back sufficiently to avoid arry conflicts with turning vehicles and visibility at the intersections. Acknowledged D. Where the residential streets dead-end, provisions should be made to provide a vehicular turnaround until the roadway are continued A concrete cross-section is required Turnaround shall be in a dedicated easement. Done and shown on plans. 4. Mews: A. The building overhangs shown encroach into the public street. Recommend City Attorney's office be contacted to determine if street license agreement is appropriate and what, if any, insurance/indemnification is required and what provisions are appropriate to provide for fUture maintenance. Though not applicable to the public infrastructure plans, this item was recommended for approval by P & Z on November 21st, with qualifications. Columbus' attorney is preparing license agreements. B. Portecochere between building 􀀧􀁾􀀢􀀠& "B" encroaches into the public right-ol-way. Street license agreement seems necessary. Recommend City Attorney's office develop appropriate license and advise regarding insurance, indemnification and maintenance requirements. If concept is approved, we recommend a minimum vertical vertical clearance of18 feet and that the developer locate all columns outside of the right-ol-way. G:\PROJ\Ol182204\MR10RESP.ACO 3 HUITT-ZOLLARS, INC. -12/12/95 DRAFT Architectural issue (See 4A) C. The current proposal requests that the mew's be constructed with a swale down the middle. If this section is approved, then an additional variance may be required from our drainage standards to vary from our requirement to maintain one (l) lane clear ofconcentrated storm water. The developer has proposed to allow a maximum depth of3" in the mews. It appears that the maximum spread ofwater would be approximately 25feet with a "V" section and 35 to 45feet with a parabolic section. Ifthe swale in the middle ofthe mews is approved, Public Works recommend a concrete swale be placed in the center to facilitate the conveyance of the irrigation, washing, and drainage water; and to protect the deterioration ofthe bricks and jOints where water may regularly traverse. The concrete drainage way is a variance from the original proposal that showed 100% brick mews but does not appear to be a dramatic departure from their current proposal. As a minimum, the current pointed concrete elements should be eliminated to avoid spalling and breaking. As proposed, they may be difficult to maintain if they get chipped or broken. The inverted mews section has been recommended for approval by P & Z. We have eliminated most of the brick in the valley area of the pavement but still have bands which cross at several locations. It is possible that some deterioration of the binder between the bricks could occur over time due to concentrated runoff. However, there are several other issues to consider: • Stormwater flows in the mews are extremely minimal. • The bricks are set in an asphaltic binder course and swept with cement stabilized sand. • A continuous concrete valley in the mews would make it look like a wide flat drainage ditch rather than an intimate public space. • Periodic maintenance of all streets will be required anyway and the potential need for repair seems relatively minor compared to the importance of creating the right kind of space. We have, therefore, shown the periodic brick crossings crossings of the mews as designed and requested by the landscape architect, which eliminates the pointed pattern in favor of a more practical rectangular pattern. Please let us know if this is acceptable. 5. Mildred: A. If the reduced cross-section is approved, the relocation of the existing 24" waterline is recommended Done G,\PROJlOII&2204IMEMORESP.ACO 4 HUITT-ZOLLARS, INC. -12/12/95 DRAFT B, Ingress, egress and parking adjacent to the rotary shall be located so that they do not interfere with the operation of the rotary. Additional design information is required to determine the appropriate location See Roundabout Study C. Recommend conferring with the City Attorney's office to determine the steps necessary to ejfoctuate the right-of-way abandonment, ifconceptually approved by the Council. Abandonment documents are being prepared by Columbus' attorney for City Council approval concurrent with fInal plat approval. D. The current proposal shows an encroachment into the public right-of-way. Recommend City Attorney's office be contacted to determine if street license agreement is appropriate and what, if any, insurance/indemnifications required and what provisions are appropriate to provide for future maintenance. Architectural issue -not pertinent to infrastructure plans. 6. Alternate material for brick accents bands, crosswalks, sidewalks, streets, etc .. , should be considered In the past, the Town has successfully used patterned concrete or pave stone (placed on a concrete base) to give an appearance of brick with more durability, serviceability and less susceptibility to settlement. See Item #6 on September 5th memo. 7. Vehicular visibility should be provided for all streets, mews and driveway approaches/intersections. Our current standards require a minimum visibility triangle of 35 feet be maintained at all entrances/intersections to the street. Recommend our urban planners evaluate this practice to determine if under urban standords an alternative design is appropriate where the garage exits intersect the streets. See Item #7 on September 5th memo. 8. Site Plan: A. The current proposal encumbers Conference Centre property to access garbage and electrical facilities for building "B", EnCUIllbrance and access from city property is no longer required. B. Garbage collection utilizes public right-of-way for dumpster pick-up and consolidation. Ifapproved, recommend a thickened section ofpavement to prevent future deterioration of roadway/sidewalks sections. How are the dumpsters serviced when there is a car parked in front ofthe doors adjacent to the park or Quorum? G:IPROMI182204IMEMORESP.ACO 5 HUITT-ZOLLARS, INC. -12112/95 DRAFT Pavement has been thickened in these areas. C. Provision for loading and unloading of vehicles is not apparent on information provided. Loading zones will be posted throughout the property and are shown on the plans. D. There appear several inconsistencies between the development plans, civil plans and landscape plans regarding the location ofmedian opening, paverslbricks and crosswalks. Recommend revising plans to provide consistency and allow complete review. The definitive plans for most elements are the public infrastructure plans by HuittZollars. Any differences between these plans and the concept or development plans are due to refmernents inherent in final design. There should be some latitude for staff to judge if the construction plans meet the intent of the more conceptual prior plans. Please let us know if there are any remaining discrepancies that pose a problem. E. Parking is not permitted in crosswalks. Recommend the UIIe ofsidewalk eyebrows to protect pedelltrians and minimize crossing widths. Parking areas should be located so they do not shield the pedestrians prior to crossing. Recommend that out urban planners provide appropriate detail for the eyebrow. Parking is not intended in crosswalks and we believe that final plans address the safety of pedestrians at these crossings. F. Recommend that a sidewalk eyebrow be provided on street "An ('R-4'J for the garage entrance to prevent encroachment ofparking on the minimal driveway width. Parking will be restricted by signage as shown on the plans. G. The plan appears to detail tree diameters of 4". This is not consistent with the proposal to place 8" diameter mature trees within the right-oi-way. Our estimates for infrastructure improvements were based on 8" diameter trees. 200 gallon trees are proposed in all locations except the mews which will have 100 gallon trees. This has been approved by Slade Strickland. H. The original details for Quorum Drive illUlitrated a double row of trees in the median. Estimates for infralltructure participation was based on a double row of trees in Quorum. The City Manager has stated that wholesale removal of the existing trees in the Quorum median is undesirable. In addition, there is not adequate space for a double row of large canopy trees. Therefore, the plan, as acknowledged by Slade G:\PROJ\OI182204\MEMORESP.ACO 6 HUITT-ZOLLARS, INC. -12/12/95 DRAFT Strickland, is to selectively remove existing trees and supplement them for a more uniform look. I The plans appear to indicate light fixtures strung across the mews on wire. Our cost estimates for public participation assumed pole mounted fixtures. If this assembly is approved, Public Works recommends that TU be contacted regarding whose lights they are and the Fire Department determine what impact they have on their ability to provide service. If they are a private facility, we recommend the City Attorney's office be contacted to develop the appropriate license. The plans indicate fixtures in the mews strung on cables attached either to the buildings or, where future buildings are proposed, temporary poles. The fixtures will be maintained by the developer but will be part of the overall system, whether it belongs to T.U.E. or the City. Columbus' attorney is working on license requirements. J. Provide survey seal by licensed surveyor with closure documentation. As we have discussed, the majority of the district has been surveyed and a certified drawing is available. This does not, however, include the Gaylord property adjacent to the tollway which was delineated based on deed records. We cannot, therefore, sign and seal a boundary survey of the entire district at this time but have provided a boundary "exhibit" which we believe meets the intent of the requirements. K The Park dimensions on the site plan do not appear to match the survey. Does Building "A" encroach into the park space? The public sidewalk between building A and the park is on park property, therefore, the park space enclosed by the proposed wall is somewhat smaller than the space on the boundary exhibit. L. What are the dimensions ofthe proposed parallel parking spaces? The length of a parallel parking space was considered 22 feet, however, we do not intend to stripe them. M What do the dashed lines on Mildred and the residential streets represent? These have been clarified on [mal plans but they were the limits of parking (or an imaginary eyebrow). N It is difficult to determine where the curbs stop and start. Ifa curbless section is desired for the mews, recommend stopping the curbs after the curb returns to control drainage, traffic and parking. Clarified on [mal plans. G:\PROJ\O 1182204\MEMORESP.ACO 7 HUITT-ZOLLARS, INC. -12112/95 DRAFT 0. Typical street sections are required. Done P. Additional information required on utility locations. See preliminary plat comments. Done Q. Provide data regarding width of streets, driveways, entrances to parking areas/structures and calculations ofimpervious cover. Done R. Provide plan ofexisting and proposed gas, electric, telephone and cable necessary to serve this development. Existing facilities are shown on final plans and an allocations of space for proposed extensions in each roadway is shown in typical sections. The fmal layouts of these systems are still being developed by the utility providers. 9. Additional comments associated with the preliminary plat/construction plan submittal dated September 5, 1995. Acknowledged 10. Resubmittal to address review comments recommended. Acknowledged G:\PROJlOI182204\MEMORESP.ACO 8 HUITT-ZOLLARS, INC. -12/12195 DRAFT ADDISON CIRCLE RESPONSE TO CITY REVIEW COMMENTS IN MEETING OF NOVEMBER 21. 1995 FROM JOHN BAUMGARTNER 1. Material cut sheets with engineer's certification regarding application, operation and maintenance (i. e. bricks, pavestone, street furniture, etc.) Materials Cut Sheets are provided in the bid documents or are detailed on plans for the following items: Benches Street Lights Trash ClmS Tree Grates Tree Fences Bollards Our inclusion of these items, either referenced on the signed and sealed plans or in the signed and sealed bid documents is our certification that, to the best of our professional knowledge and belief, they are suitable for the applications indicated. Please let us know ifthe Town feels otherwise or ifthere is insufficient information for your own evaluation. 2. Funds for Phase 2 improvements are not available -Phase 2 improvements can be included but must be separately identified in bid tabulation. A separate bid schedule has been provided. 3. Offoite easements required Offsite easements are indicated on the plat with special language calling attention to he fact that they are outside the boundaries of the platted lots. All owners of property affected by these easements will execute the plat (Columbus, Gaylord and the Town of Addison). 4. Utility company sign-off see list. Please clarify what is required. 5. Pavement markings and signage plan. Pavement markings and signage are now shown on the plans. 6. Hydrant details (L e. specific location paint, etc.) Specifications cover the locations and color of fire hydrants. G:\PROJ\Q[ 1822Q4\MEMORESPACO 1 HUITT-ZOLLARS, INC. -12112/95 DRAFT 7. Overall water/wastewater plan that depicts lines, hydrants services, sizes, etc. An overall water and wastewater plan has been added. 8. Thicken sidewalk and designed bricks for areas servicing garbage transformers, switchgear, loading traffic, etc. Sidewalks adjacent to service areas have been thickened to 6-inches of concrete under the brick. The sidewalk brick is designed for light duty vehicular loads and is appropriate for these locations (except at the 40 yard compactor where heavy duty materials are specified). 9. Meter installationslback flow prevention devices -private property improvement -details required Why 2-2" -use compound meter 3" or 4"? What is a service? Traffic safe boxes? Typical detail -materials sheet -engineering certification, bollards location detail. We have reviewed the proposed domestic water meter configurations with the mechanical engineer for the private development work. He prefers to stay with multiple 2-inch meters because they are more cost effective than larger meters and they are easier to fit into the streetscape. The purposes for the various services have been clarified on our plans and the responsibility between public and private work has been better defined. There is nothing proposed that is other than standard municipal construction for water meters. There is no reason to use heavy duty boxes or bollards for these elements. 10. Services to jitture phases. Where appropriate, service stubs have been provided to future development areas. 11. Hydrant location/detail turn radius -bollard protection. Fire hydrants have been located outside the required 30-foot turning radius at all intersections and are set back from the edge of pavement or curb. We do not believe special bollard protection is justified. 12. What happens to existing lights and trees? The disposition of existing lights and trees is now noted on the plans. 13. Spoils disposals. G:IPROJlOII82204IMEMORESP.ACO 2 HUITT-ZOLLARS, INC. -12/12/95 DRAFT The specifications indicate that the Contractor is to dispose excess street excavation onsite to be used by the private contractor to fill the building pads. Excess spoil from the storm drainage outfall is to be stockpiled adjacent to the channel per the plans. Excess utility spoil is to be coordinated with the private construction but is ultimately to be hauled off for disposal, if not needed elsewhere. 14. Typical details. Typical details for items not covered by City or other applicable standards are included in the plans. 15. Typical notes. Typical notes for items not covered by City or other applicable standards are included in the plans. 16. What type of information is available for contractor to establish and maintain control. The horizontal control plan indicates the points which will be set for the Contractor. It will be his responsibility to maintain this control however he sees fit or pay to have it reset. 17. Quality control plan for contractor. The Contractor is responsible for his own quality control. 18. Waterline under the rotary? The existing 24-inch waterline under the roundabout is to remain unless otherwise instructed by the Town following refmement of the design for the central feature. 19. Street light design -private system. We are prepared to perform a complete electrical design for the street light system if the Town chooses to take it over. However, our plans currently reflect fixtures and details relating to a system to be owned by T.V. Electric. 20. Mews street lights? Details for the mews lighting have been added to the plans. 21. Plan submittals to Carmen, Sasaki, fire, police, and Slade Strickland. Separate customized sets of partial plans will be supplied to you in this transmittal for each of the reviewers listed. 22. Seal before submittal. G:\PROJ\OI182204\MEMORESP.ACO 3 HUITT-ZOLLARS, INC. -12/12/95 DRAFT The current submittal is fully signed and sealed. 23. Who is providing survey control throughout the project? (i.e. for franchise utilities?) All entities and contractors are responsible for their own control based on our horizontal control plan and the plat (R.O.W.) monumentation. 24. Location ofswitchgear/transformer. Switchgear locations are shown on the plans along with several transformers that will serve public functions. All other transformers are on the developer's property, most in parking garages. 25. Quorum crosswalks? We have consulted with the landscape architect and further considered the proposed brick crosswalks across Quorum Drive. We believe that the crosswalks should remain for the following reasons: It will be better to do all of our crossings of Quorum Drive now while traffic is the lowest it will ever be and there are no residents in the district. There is adequate sight distance at the railroad crossing and this crosswalk is intended to work with the Town's proposed hike and bike trail. 26. Water tower property line? Our surveys reflect the water tower (Town) propertyline correctly to the best of our professional knowledge and belief. It appears that the fence is constructed in the wrong location. 27. Signed survey. See response to Item #8J from the October 16th memo. 28. 2 year maintenance bond. The instructions to bidders and contract requirements specifY a 2 year maintenance bond. 29. Street bores. Based on location within the construction zone, the primary candidate for street boring is electrical duct across Quorum Drive. However, due to the nature of a concrete-encased duct system with its multiple conduits and spacers, boring is very difficult and costly. We have positioned the ducts to take advantage of pavement removal for crosswalks and recommend that they be installed by cut and cover methods. O;IPROJ\Ol182204'MEMORESP,ACO 4 HUITT-ZOLLARS, INC. -12/12195 DRAFT ADDISON CIRCLE RESPONSE TO COMMENTS ON THE MODERN ROUNDABOUT STUDY FROM BARTON-ASCHMAN. ASSOCIATES, INC. Comments have been received, both in meetings and in Barton Aschman's review memo, which express concern about the implication in the roundabout study that artificial constraints may have been placed on the designer. This is indeed the case and we purposefully noted it in the report. However, there is possibly a need to elaborate further on this point. First, there is apparently a misunderstanding that, in roundabout design, bigger is better. This is not true. A larger diameter circle in and of itself does not necessarily increase the capacity or safety of operation of the roundabout. The beauty of a modern roundabout is that it can function well in a relatively smaIl amount of space. It is true that there are no existing structures to limit the size of the proposed Addison Circle roundabout. However, if available space were our only consideration, we could propose several other methods of handling handling the traffic, but they might not be consistent with the goals of the Urban Center District. The roundabout geometry that we have proposed was developed in an iterative process between the roundabout specialist (Mr. Peter Doctors, P.E.) and the Addison Circle project design team, Huitt-Zollars (Engineers), RTKL (Architects) and Newman, Jackson, Bieberstien (Landscape Architects). The initial outside right-of-way diameter of 300 feet was established based on research into the "typical" size of modern roundabouts. Mr. Doctors was provided this information with the intersecting geometry ofexisting and proposed Mildred Street and Quorum Drive and asked if it was adequate. His response was that it was as much or more space than he had ever had in which to design a roundabout and he proceeded with the design without further input from the design team other than a target dimension of approximately 100 feet for the outside curb radius and traffic projections. Based on the outer curb dimension, the traffic characteristics to be expected and the alignment and lane configurations of the approaching roadways, Mr. Doctors arrived at a design for the roundabout. The primary components of the resulting design were the deflection, flare and inside curb radii of the entering and exiting roadways. The initial design operated at a level of service A. The design team reviewed the geometry with respect to the urban design goals of the district which included the following: • Adequate space for public art • Pedestrian safety and comfort • Definition of the urban space being created • Impact on the public streetscape It was a basic understanding that the traffic issues were covered by Mr. Doctors with his design. It was the team's opinion that the design that was proposed compromised the intent of an urban enviromnent because the dimensions of the flare and the very large inside radii of the deflection at the entering and exiting roadways were too rural in character such that they: G:\PROJ\Ol182204\MEMQRESP.ACQ I HUITT-ZOLLARS, INC. -12112/95 DRAFT Destroyed the circular shape of the urban space by their very wide penetrations of the circle (which in turn eliminated many proposed trees that were intended to defme the circle and shade pedestrians); Created excessive distances for pedestrians to cross, even though median refuge was provided; Clipped the comers of the sidewalks narrowing the space for the sidewalk and streetscape. The design team asked Mr. Doctors if he could modify any of the parameters to narrow the flare and/or reduce the radii of the inside curbs at the deflection. He responded that no appreciable changes could be made given the existing conditions without a reduction in the level of service. He was asked to revise the design to address the team's urban design concerns with whatever reduction in level of service he felt he could support. In summary, the Addison Circle development and the Urban Center District are fIrst and foremost an urban neighborhood. It is not our goal to create an intersection for Quorum and Mildred that operates at the highest possible level of service and then fIt the development around it. It is our goal to create a quality urban environment fIrst and build into it an adequate ability to deal with traffic. The roundabout concept was chosen as the mechanism for handling this major intersection more because of the interesting space and focal point which it creates than for its inherent ability to improve the level of service. Therefore, its final design considers its impact on the district from more than one perspective and is necessarily a compromise. (Response to comments on traffic generation and levels of service to follow.) G:\PROJ\O 1 1 82204\MEMORESP.ACO 2 HUITT-ZOLLARS, INC. -12/12/95 DRAFI' ADDISON CIRCLE RESPONSE TO OTHER ITEMS MENTIONED IN THE REVIEW MEETING OF NOVEMBER 21, 1995 AND IN VARIOUS TELEPHONE CONVERSATIONS WITH JOHN BAUMGARTNER 1. Proximity ofparallel parking to intersections/or, length ofneckdown area. (Per AASHTO and MUTCD.) AASHTO and MUTCD differ somewhat in their rationale and in the detail of their approach to this issue. However, the common element seems to be a desire for a minimum of 20 feet of clear area between crosswalks and the beginning of parallel parking. We have provided 20 feet from crosswalk to parking transition which provides 26 minimum feet to the first car to the crosswalk and up to 46 feet from the mst car to the curb line of the intersecting street. 2. We have added an 8-inch waterline stub-out across Mildred to the Special Events Area. 3. Overhead power line (and other utilities) to elevated water storage tank, conference center, etc. We are coordinating with the utility companies to provide interim service during construction and permanent service service once the duct systems are in place. Our plans currently reflect early removal of the overhead line through coordination between the contractor and the utility companies. We expect to meet with T.U.E. in the next week to review their proposed system and will discuss this issue further at that time. (MORE TO FOLLOW) G;\PROJ\O 1182204\MEMORESP.ACO 1 HUITT-ZOLLARS, INC. -12/12/95 60 o THE METROCREST NEWS January 4, 1996 M075 legal· Metrocrest ADVERTISEMENT FOR BIDS 1. Sealed bids addressed to the Town of Addison, Texasl for Paving, Drainage! Wastewater,_Watert Streetscape, Electrical Ductbank, and Park Improvements for ADDISON CIRCLE, 􀁐􀁾􀁁􀁓􀁅􀀠I PUBLIC INFRASTRUCTURE for the Town of Addison, Texast hereinafter called "Town /I in accordance with plans, speclflcallons and contract documents prepared by Huitt-Zollars, Inc., will be received at the oftice of Clyde Johnson, Purchasing Manager, Finance Building, 5350 Bell Line Road, Addison; Texas until 2:00 p.m. on the 261h day of January, 1996. Bids received by the appolnled time will be opened and read aloud, Any bids received after. closing time will be returned unopened. . 2. The Contractor shall Idenllfy his bid on the oul· side of Ihe envelope by wrlll ng the words ADDISON CIRCLE PHASE I PUBLIC INFRASTRUCTURE. .3. Bids shall be accompanied by a c.shler's check or certified check upon. nallonal or state bank In an amounl nol less less than five percent (5%) of Ihe to· tal maximum bid price payable wlthoul recourse to the Town of Addison, or a bid bond In Ihe Same amount from a rell.ble surety company licensed by the Stale of Texas to act as a Surety, or a Binder of Insurance execuled 'by • surety company licensed by the State of Texas to act as a surety or Its autho· rized agent as a guaranlee Ihat the bidder will en-. fer into a contract and execute a Performance Bond within three (3) business days after notice of award of conlracl to him. 4. Plans, speCifications and bidding documents may be secured beginning at 9:00 A.M. Monday, January B, 1996 from Clyde Johnson, Purchasing Manager, Finance Building, 5350 Belt Line Road, Addison, Texas for Ihe non-refundable sum of $25,00 per set. 5. The right is reserved by Ihe Mayor and the Town Council as the interest of the Town may require 10 reject any or all bids and to waive any Informality in bids received. 6. The Bldd,er (Proposer) musl supply all the information required 􀁢􀁾􀀠the Proposal Form. 7. A Performance Bond, Labor and 'Material Pay· ment Bond, and Mainlenance Bond will be required by the Owner, each Bond shall be in Ihe amount of 100% of Ihe lotal conlract amount. Bonds shall be Is· sued by a surety company licensed by the Slate of Texas 10 act as a Surety. The performance and.pay· ment bonds shall name Ihe Town of Addison and Gaylord Properties, Inc. (Gaylord), 10111 North Central Expressway, Da"as, Texas 75231, (214) 7399999 and Columbus Realty Trust (Columbus), 15851 North Dallas Parkway, Suite 855, Dallas, Texa. 75248 (214) 770·5151 as joint obligees (or such other entities as may be designated at the time a conlract is execuled). 8. For information on bidding or to secure bid docu· ments, call Clyde Johnson (214) 450·7090. For Information on the work to be performed, call John Baumgartner, City Engineer, (214) 450·2886 or Ken Roberts, Huitt·Zoliars, Inc. (214) 871·3311. 9, This prolect consists of prOviding paving, side· 􀁷􀁡􀁬􀁾􀀠water, wastewater, landscape, stormwater. electriC duclbarrk, and other miscellaneous 1m· provements as shown on the plans and' in 􀁡􀀧􀁣􀁣􀁯􀁲􀁾􀀠 dance with the speclflcallons. 10, The contract will be assigned to and Ihe con· struction of the prolect wm be administered by Co· lumbus Realty Trust, and/or Garlord Properties, their successors and assigns per the Master FaclHtie. Agreement with the Town ot Addison. 11. A Pre·Bld Meellng will be held al 2:00 p.m. on January 17, 1996 al the Addison Service Cenler, 16801 We.tgrove Drive, Addison, TX. All bidders are encouraged 10' attend. TOWN OF ADDISON MN CPN: 100 PUB: 01/04/96 & 01/ll/96 SECTION "AU ADVERTISEMENT FOR BIDS Sealed proposals, addressed to the City of Carrolllon, will be received at Ihe office of the City Engineer, City Hall, Engineering Department, 1945 E. Jackson Road, Carrollton, Texas 75011-0535, until 10:00 a,m., on January 19, 1996 for: WATER LOOPING 94-2W INTERSTATE 35E WEST SERVICE ROAD 12" WATERLINE PROJECT WEST CROSBY ROAD TO THIRD STREET Bidders must submit, with their bids, a a cashier's, or certified check In the amounl of five percent (5%) of Ihe maximum amounl bid, payable without re· course to the City of Carrollton, Texas, or a Propo$& al Bond in the same amount from an approved Surety Company (according to the latest list of companies holdlQ9 cerllflcates of approval by the State Board of Insurance under 7.19·1 of the Texas Insurance Code) as guaranlee that the Bidder will enter into a contract and execute bond and 􀁧􀁵􀁡􀁲􀁡􀁮􀁾􀀠 lee forms provided within ten (10) days after award of conlract to him. The successful Bidder must furnish Performance and Payment Bonds each 'In Ihe amount of 100% of the contract price from an approved Surely Com· pany holding' a permit from Ihe State of Texas, to act as Surety and acceptable according to Ihe lalest list of companies holding certificates of approval from the Stale Board of Insurance under 7.19·1 of the Texas Insurance Code. The successful bidder must also be able to show avldencelhat It Is autho· rized 10 do business In Ihe Slate of Texas prior to execullng the contract and that they have performed protects of comparable size and type In the pasl three years. All unit price. must be slated in both script and figures. The Owner reserves the righl 10 rejecl any or all bids and 10 waive formalities. In case of ambiguIty or lack of clearness In stating Ihe price In the bids the Owner reserves the right to consider Ihe most advantageous construction thereof, or to 􀁲􀁥􀁾􀀠 iecl the bid. Unreasonable or unbalanced unil price 'wlll be considered sufflcienl cause of relection of any bid or bids. Bidders are expected 10 Inspect the sile of the work and to Inform Ihemselves regarding local condl· lions 8. conditions under which the work Is 10 be done. Attention Is called to Ihe 􀁰􀁲􀁯􀁶􀁬􀁳􀁬􀁯􀁮􀁾􀀠of Ihe Act of the 43rd Legislature of the State of Texas and subsequent amendments concerning' the wage scale and payment of prevailing wage specified. Prevailing wage rate will be established by the City of Carrollton for this project. All bidders must comply with Ihe rules and regulations for Ihe AmeriCans wi,th Disabilities Act of 1990. Instructions to Bidders, Proposal Forms, Specifications, Plans and Contract Documents may be examined withoul charge at the office of the City Engineer, City Hall, Engineering Department, 1945 E, Jackson Road, Carrollfon, Texas 75011·0535, and/or may be obtained for a $15.00 non-refundable fee. A pre-bid meellng will be held at'the office of Ihe' City Engineer, City Hall, Engineering Departmenl, 1945 E. Jackson Road, Carrollton, Texas, al 10:00 A.M" on January 12, 1995. CITY OF CARROLL TON, TEXAS un7" PENNY AND ASSOCIATES TRANSPORTATIQN ENGh'iEERS 1411 NATCHES DRIVE ARUNGTON, TEXAS 76014 817/465-1072 .-', HUITT-ZOLlARS Engineering I Architecture DaIW • Fol'f Worth • Ho_ • El Puo • l'Itctmix • Counry FACSIMILE TRANSMITIAL 131􀁾 􀀢􀀧􀀧􀀧􀁾􀀧􀀧􀀧􀀧􀀧􀀠 Dale: Dt!X= 28, Fax No. • ''''5 . H-Z Proj. No. 01-/'221. -of No. of 􀁐􀁡􀁧􀁥􀁳􀀺􀀮􀀭􀀭􀀽􀁾􀀻􀀬􀀮􀀮􀀮􀀮___ (Illclu.dillg Cover Sheet) TO: 1Qwa (If AJJ'flrn dihn 􀁇􀀴􀀢􀁾􀀠 Cl URGENT 0 Fot YOW' Revi_ D Please Call Upon Receipt 0 OIig. To Follow By Mail 􀁮􀁏􀁍􀀺􀁾􀁾􀀠 SENT BY, ,>12/.3/;(;<. •• ,,/TIME: I:J flu dr'1 DATE: t)-,:N Y'f.q you "-4 ..., ,....1...... _ ..., W 1'......0. T_. tH<-._M •. 1 _ ., ... 􀁾lIJrGj ..... (.!U) Brl· ,1111. 1JWnkycw. 3131 McKiMey 􀁁􀁾􀀢􀁵􀁥􀀠• Suiu 600 • DtJlns. TU4.S 7510<1· (114) 87/-3311 • FAX (114) 87/.0757 Columbus of such bids and the City Sr.aff'8 proposal to the City Council regarding the award of the bid. 'lbe City Counc1l shall thereafter awanl the bid. 2. In conjunction and simultaneous with the construction of the Improvements, Gaylord and Columbus will be constructing certain private improvements upon that portion of the Properly included within the applicable phase or subphase. Therefore, upon the award and eueutiDn of the construction conln1.Ct between the City and the contractor and in oRler to coordillate the consttuction of the public and private facilities, the City shall assign all of its rights, powers, duties and obligations under the construction contract to Gaylord and Columbus. Gaylord and Columbus shall then:after act and serve as the owner and construction manager under such construction contraCt for all PUIpOses, including inspection, material testing, staking, supervision and coordination of all construction work, in accordance with the following: (a) uaylord and Columbus shall usc their best efforts to insun: that aU Improvements are completed in a timely manner in accordance with the construction contract documents, plans and .speciflcaliol13. Gaylord and Columbus shall thoroughly inspect the work of the contractor to guard the City against defects and deficiencies in the Improvements without assuming responsibility for the means and methods used by the conl1'aCtor. (b) Except as provided in Subpmagraph (I:) of this Section 6.B.2., Gaylord and Columbus shall fully and completely payor settle, by litigation or otherwise, any claims of the construction contractor arising out of the performance of the construction contract without involving the City. (1) Any construction conllaCt for the cDllStruction of the Publ.ic Infr.amucture Improvements shall specify. that the contractor shall look solely to Gaylord and Columbus concerning any claim under the contract. In accordance therewith: (i) For each such construction contract Gaylord and Columbus shall acquire and maintain, during any period for which a phase or subphase of the development of the Properly is under construction, comprehensive general liability insuflUlce in the amount of the construction contract of $1,000,000, whichever is greater. Such insurance shall cover any and all claims which might arise out of the COJIStruction contract, wIIet1ter by the contractor, a subcontractor, materialman or otherwise. All such insurance sbaIl: (a) be issued by a carrier which is rated •A-i· or better by A.M. Best's Key Rating Guide and licensed to do businm in the State of Texas, and (b) oarne the City as an additional insured. Certified copies of all of such policie8 sball be deliveml to the City upon the execution of a constroction conln1.Ctj provided, however, that the City, in its sole discretion and in lieu of certified copies of such polieies, may permit the dolivel)' of certificale!l of insuraru:e togetbe:r with the deelaralion page of such polieies. along with the endorsement naming the City as an additional insured. Each such policy shall provide that, at least 30 days prior to the cancellation, l!OJ1-renewal or modification of the same, the City sbaIl receive Wlitten notice of such cancellation, non-renewal or modification. (b.) Gaylord and Columbus Shall also indemrd1Y the City. its officers and employees agabIst. and hold the City, its o!ficeIs and employees ilarmless from, at Gaylord's and Columbus' cost, any and all actions, causes ofaction,lawsuits, judgments, claims, damages, M Ac .....'JU 5 ' ...... ........ ----.. .. CO$lS or fees, including :reasonable 􀁡􀁴􀁴􀁯􀁭􀁥􀁹􀀧􀁾􀀠fuelI (including claims for contractual damages, or claims for injuty to petSOn or propeny or death of any person) resulting from or based on, in whole or in pan, any act or omission of Gaylord and Columbus under a construction or professional services contract entered into in the development ofthe Ptupedy during CODStruction of the Improvements and until the City's Engineer accepts the Improvements as finally complete, The provisions of this Subparagrapll (b)(l)(ii) shall survive the termination of this Agmem.ent. (0) In the event that claimll from a contractor under a 􀁾contract result from the wroogful failUle by the City to make constnIction payments in acc:ordance with the terms of this Agreement, Gaylold and Columbus may seek reimbursement in accordance with this SlIbpamgraph (c). In the event Gaylord and Columbus intend to seek reimbursement from the City for the expense incurred by Gaylord and Columbus in resolving any claim caused directly by by the City's wrongful failure to make such construction payments, Gaylord and Columbus shall notify the City in writing of the claim and any proposed settlement or IeSOlutioo. The City reserves the right upon such notice, and at the City's sole election, to make an audit of all boob, records, accoUJIts and other data of the construction contractor relating to the claim and overall performance of the constnIction contract before approving payment ofsuch claim. The construction contract shall provide for the City's right to audit IUch claims, (d) GayloId and Columbus shall review all invoices or pay estimates received from the contractor and forwam the same to the City for payment with such supporting documentation lIS the City may reqm. All payments for work performed under the construction contract shall be made by the City to Gaylord and Columbus for forwaming to the con$1lUction contractor. The City shall not make a payment under any such invoice or pay estimate unless GayloId and Columbus have provided to the City a cem&alion regmling tbe invoice or pay estimate and Gaylord and Columbus have reviewed and approved tbe same. Gaylord's and Columbus' certification shall be by affidavit sworn to by tbe appropriate official of Gaylord and Columbus authorized to subotit the same, and shall certify that the estimate of work completed for the relevant period is true and correct to the best of Gaylord's and Columbus' information and belief, has been measured and verified in accordance with the c:onstnIction contract documents, and that all construction contract preconditions to payment bave been met. Copies of all matmai testing results sball be fumi!hed with the certification. 3. All change orders shall be processed and approved .in accordance with the City's procedure for the revicw and approval thexeof, 4. The COIIstructioo contract shall require, among other thingll, that the conttactor provide pc:dOrmana: and payment bonds in a form acceptable to the City. The performance and payment bomb shall name the City and Gaylord and Columbus as joint obligees. S. All Public Inliastructure Improvements shall become the sole property of tbe City upon completion of the work and acceptance of tbe work by the City. Upon final completion of the Improvements and acceptance thereof by the City in accordance with tbe construction contract for the Improvements for each phase or subphase, the City shall take the Public Infmstructure Improvements free from any liens or eacumbmni:es tben!on. except for lilly private utility easements and any rights reaerved mgarding publie parking, Memorandum TO: John Baumgartner Town ofAddison FROM: Gary Jost DATE: January 5, 1996 SUBJECT: Addison Roundabout -Additional comments We have completed our review of the sensitivity analysis completed by Ourston and Doctors and design plans prepared by Huitt-Zollars for the proposed Addison Roundabout. This memorandum presents our findings. Sensitivity Analysis Ourston and Doctors present in their sensitivity analysis findings based on 50 percent and 85 percent confidence levels. Ifqueues and delays are calculated at a 85 percent confidence level, this means that one can be 85 percent certain that actual queues will not be greater than the calculated values. Based on the uncertainty of operations of the first modern roundabout in North Texas, we would recommend that the 85 percent confidence level be used for calculating operating conditions of the planned roundabout. It should also be noted that there is currently no consensus in the transportation profession regarding the most appropriate traffic engineering tool for analyzing modem roundabouts. The Transportation Research Board has established a committee to review current capacity analysis techniques and develop a new Highwav Capacitv Manual by the year 2000. This committee, chaired by Mr. John Zegeer of Barton-Aschman Associates, Inc., is working to include a recommended procedure for analyzing modern roundabouts in the new manual. The sensitivity analysis reports that at the 85 percent confidence level traffic volumes can be increased, from volumes originally projected, by 4 percent in the A. M. peak period and 11 percent in the P.M. peak period while still maintaining a level of service D. This suggests that the current design is highly sensitive to small increases in traffic volumes. With an II percent increase in traffic volumes, and assuming that 10 percent ofdaily traffic OCcurs during the P.M. peak hour, one could estimate that the effective capacity of Quorurn Drive, assuming 10,000 vehicles per day (vpd) on 1 􀁾􀀠 LDPARSONS Mildred, would be less than 30,000 vpd. Of particular note is the comparison of average and maximum queue lengths between the original projections and the maximum volumes that can be accommodated at Level of Service D. Tables 1.0 and 2.0 present this comparison for the A.M. and P.M. hours, respectively. Table 1.0 Average and Maximum Queues A.M. Peak Hour ApPROACH LEG AVERAGE QUEUES ! ("'EH) MAXIMUM QUEUES (VEH) ORlG. LOSD ORlG. LOSD NBQuorum 0 I I I ! WBMildred I I 1 I SB Quorum 17 30 35 69 EB Mildred 4 5 6 9 Table 2.0 Average and Maximum Queues PM. Peak Hour I i ApPROACH LEG AVERAGE QUEUES (VEH) ORlG. LOSD MAXIMUM QUEUES (VEH) ORlG. LOSD . NBQuorum 4 12 6 25 WB Mildred 5 30 10 57 SBQuorum I 1 I 2 EB Mildred 1 2 2 3 As shown in these tables, average and maximum queues increase significantly with very little increase in total volume entering the roundabout. Based on the sensitivity to small increases in peak-hour vclumes identified in the analysis conducted by Ourston and Doctors, it is our recommendation that the design of the planned Addison Roundabout be analyzed further to provide more stable conditions at these anticipated volumes. 2 OTHER DESIGN CONSIDERATIONS Parking On -street parking along Quorum and Mildred should be restricted within 150 feet of the roundabout on the departure legs ofthe roadways to provide adequate sight distance. Paving Tvpical Section The typical section for Quorum Drive specifies a full sawcut with existing steel to remain. The full depth sawcut will also cut the steeL Ifa full depth sawcut is desired, steel dowels will need to be drilled and inserted into the existing concrete pavement Signing and Markings • The stop sign at Witt Mews and Mildred should be moved behind the barrier free ramps. • The no parking signs on Mildred appear to conflict with the paving plans. • Ifpedestrians are to be restricted from entering the roundabout island, then "No Pedestrian" signs should be installed in the island. • All discussions to date regarding pedestrian crossings at the roundabout have indicated that the crossings should be located one to two vehicles behind the yield line. This needs to be reflected on the plans. • • Addison has typically utilized pavement markers rather than striping for lane delineation. • Advance warning signs for the roundabout should be provided. • Additional signs (i.e. chevrons) identifying the roadway curvature are recommended. Miscellaneous • There appears to be an abrupt change in crossfall on the north side of the roundabout at QUorum. • Loading and unloading areas should not be allowed in the area ofthe roundabout. If you have any questions, please do not hesitate to call. 3 REC'D DEC (14 BARBARA KOVACEV1CH Itlt----MANAGER MEMORANDUM DATE: December I, 1995 TO: John Baumgartner, Lynn Chandler, Ron Davis, Robin Jones, Carmen Moran, Greg Pynes, Gordon Robbins, Mary Rosenbleeth, Slade Strickland, Bob Wallingford FROM: Barbara Kovacevich RE: Columbus Realty Trust Bid Specifications Attached for your review is an excerpt from the Addison Circle Bid Specifications that outlines CRT's specific instructions on construction activities allowed during special event times. Please review this information and let me know your thoughts by Tuesday, December 5. Thank you. P.O. Box 144 16801 WESTGROVE ROAD ADDISON, TEXAS 7500t (214) 450-2851 FAX: (214) 248-7814 DRAFT -Excerpt from Addison Circle Specifications -November 15, 1995 Construction Planning and Special Sequencing Addison Urban Center Phase I is located in an area that hosts several special events throughout the year. These events will continue to be held during the construction and certain provisions must be made to accommodate them. The dates, durations and operating hours of events vary from year to year and it is therefore not possible to specify all restrictions prior to execution of the construction contract. The following information should, however, aid the Contractor in evaluating the impact of such events on his schedule. The major events and scheduled dates for 1996 are as follows: Taste of Addison Sat. & Sun. -May 18-19 Addison's Kaboom Town Wed. -July 3 􀁾􀁴􀀠 Addison's Oktoberfest Thur., Fri., Sat. & Sun. September 19-22 Run for the Children Sat. -September 21 Most events occur along Mildred Street between Addison Road and Quorum Drive, occupying areas several hundred feet north and south of of the roadway. Events that occur during construction will be designed to operate outside the area of the private development to be built on the north side of Mildred but certain events will function best if the street itself is available. Therefore, a goal of the contract will be to sequence the work to allow the use of Mildred Street for the 'T,," of 􀁁􀁤􀁤􀀻􀀧􀁏􀁏􀀢􀁾􀀧􀀠􀁾􀀭􀀺􀀧􀀢􀀠,;-lIy -/kR a 􀁾􀀯􀀨􀀮 ff Parking for events can occupy much of the vacant properly surrounding the project and access is primarily via Quorum Drive. During ___--' _____ and ______(events) the Contractor will be required to maintain 2 lanes of traffic in each direction on Quorum Drive. 􀁾􀀧􀀠 􀀭􀁉􀁊􀀭􀁩􀀯􀁾􀁾 ) (For bidding !poses, the Contractor should assume 􀁴􀁨􀁡􀁾􀁮􀁾􀁣􀁣􀁵􀁲 on the project during S ') an even At least two weeks prior to a scheduled event the Contractor shall be required to r .:§\ co rdinate through the Director of Public Works with the managers of the event and inform them 􀁾􀁜􀀠 ) f his planned construction activities during the event. Depending upon the nature and timing (S of the Contractor's activities with respect to the event's activities, a detennination will be made by the Director as to whether construction will be emporarily suspende entirely or in the " immediate vicinity of the event. ,-tV!dJu; mud k 􀁾􀀠 During the event, special effort must be made to secure the construction site and provide for the safety of the public. Though the standard speCifications and normal construction practices dictate measures to be employed, during an event, the public will be moving about in a manner that is not typical relative to this type of construction project. Chapter 4. Parking Structures and Urban Design Parking structurcst' are a far more efficient Llse of land than arc surface parking lots. A p<1rking structure lypically takes lip less land because parking is '"stacked" in levels. Most pilrking strLlcturcsarc constructed in a way that maximin's efficiency amJ economy. For example, it recently constructed COOO-spacc parking garage in Indi, TIl is :.!UnI:';C, [11/ill I () s{?n1e a new l3Iuolllill,'iL The Chicago TnlHflJt1rcported that the structure boost(:d that bhopping dislricfs off-strl>{'t parking 11, Ibid, p, 0 \11 􀁾􀁕􀀡􀁬􀁭􀁨􀁉􀁊􀁽􀀧􀀬􀀠 capacity by 30 percent. Three newly opened structures in the city's downtown Loop have boosted that areas parking capacity by 2,720 spaces, an estimated gain of 2S percent. Planning commissions and citizen groups have responded to the parking garage 􀁣􀁯􀁮􀁳􀁾􀁲􀁵􀁣􀁴􀁪􀁯􀁮􀀠boom with new requirements that force parking decks to respect their surroundings. In some cases, this has meant keeping parking facilities off certain pedestrian-oriented streets. In other cases, it means that parking garages must include groundfloor retail space; be architecturally compatible with the buildings they serve; and include landscaping improvements that enhance their appearance. PROHIBITIONS ON PARKING GARAGES In a few locations, even well-designed parking garages simply do not fit. For example, in 1986, a developer proposed a parking structure along one of Chicago's most important pedestrian areas, the State Street Mall. Actually, the garage was planned for the corner of Washington and State Streets with access only off of Washington, Despite developers' promises of ground-level retail space and a facade treatment (with an estimated cost of ovor$200,000) that respected the Marshail Ficld'sdcpartment store (across the street) and the Carson Pirie $colt department store (two bJocks away), the city planning comulission and city council strongly rejected the proposal. The city's rejection was based on the importance of State Street as a pedestrian shopping 􀁾􀁲􀁥􀁡􀀠and the city's long-range plans to intensify shopping and retail space in this arei1. Other cities, both large and small, have prohibited parking garages in certain locations. In downtown San Francisco, commercial parking garages (i,e., garages lhat are not acccss(,)ry to a business) are only permittco in locationson the periphery of downtown and only afierreview nnd nprroval by the city planning commission, This prohibiti(lO on parking garages is intenueu to maintain the pedestrian character of the city's shopping area and to promote the use of mass transil. The New York City zoning code also prohibits park. iog structures along stretches of pedl"strian-orienled sf reets such as Fifth Avenue and the Avenue of the Americas, Other cities, such as Seauleand Toronto, have, with varying success, tried to control the construction of parking garages in areas in which they may conflict with other development goals. These lotal prohibitions against parking structures are not unique to big cities. In the central core of Vail, Colorado, the zoning code prohibits anyon-site parking, including surface parking lots and parking garages. MANDATES OR INCENTIVES FOR PARKING GARAGES Some zoning codes require parking structures or provide incentives to developers to build garages rather than than surface parking, More and more communities want parking to be built up rather than spread out. In pedestrian-oriented commercial areas, cities combine the requirements or incentives for parking structures with requirements or incentives for ground-floor retail space. Cities as diverse as San Diego and Beverly Hills, California, and Vail and Aurora, Colorado, require parking to be enclosed in structures in certain circumstances. Within 􀁳􀁥􀁣􀁾􀀠 tions of Vail's commercial core, the city mandates that at 24 It'.lst nnc-h.lH of the n.'quired p oHkcs, shops. hotels, and other 􀁢􀁵􀁾􀁩􀁮􀁣􀁳􀁳􀁴􀀧􀁳􀀠with large amounts of parking to provide for 􀁾􀁬􀁴􀀠kast halF of the parking within a garage, .:m underground facility, or on the building's rooftop. In the Beverly Hills commcrci,ll-rctai! overl.1Y zone (Rodeo Drive and other posh retail streets), the city not only requires parking in multilevel struclures. but i! also requires that two complete Ievcls of these g.lragt·s be undc-rground. In San Diego's central city area z(')ning t.li5tricl. the city requires"any developer building parking "al a ratio greater than one SpiKe per 2,000 square feet of gros:; building area to enclose the parking within the principal building or a parking garage." Zoning incentives for builders using parking garages are far more common than mandatory requirements for parking parking structures. The object of these bonus systems is to shape downtowns or employment centers so that they remain compact, dense, and urban. Many of the communities of-I('ring Ihn;c ntHHlSC!1 do not \V.lnt {n t'nd up 􀁾􀁶􀁩􀁴􀁨􀀠commcr 􀁃􀁩􀁾􀁬􀁬􀀠 tln.'.lS in which businesses arc surrounded by i'I sea of 􀁾􀁬􀁳􀁰􀁨􀀮􀁬􀁬􀁴􀀮􀀠 Short descriptions of varia LIS 􀁨􀁯􀁮􀁴􀁬􀁾􀀠systl'ms for underground and multilevel stfllcturcd parking .1rcas a IT' 􀁤􀁣􀁾􀀠 scribed in the following paragraphs. • lJellevuc, W<1shington. is a major office ,111d retail centt'r in the Seattle 􀁭􀁥􀁴􀁲􀁯􀁰􀁯􀁬􀁩􀁴􀁾􀁬􀁮􀀠an',L The city's downtown zoning code includes bol1t!st·s for plazas, public art pedestrian improvements, and parking facilities. For underground pcning is used, it 1s typk ,'city'st!(lwntnwn th.ll then: have helm calls !()r itstbunlitilm. Cl)ll)mul1ity 􀁾􀀩􀁲􀁪􀁮􀁩􀁯􀁮􀀠􀁾􀁬􀁲􀁲􀁴􀀢􀁬􀁲􀁳􀀠in favor of the,,· wrecking hs tl trimlgular-slmped lot and ;'lItlpidcs em cllfry 􀁉􀁬􀁾􀀠HHl1.'lIl'd St/r/nft-fnlllf tht' Char/t's Rillt'r. It I't'rclved I't'rclved tflt' GOI·enror's Design Aumrd for Mossnc1!tlscffs i111986. (Peter VWHlt'rwnl'k.'r) )1j"t' , T r 29 quirements. Many of these cities have designated specific streets where they want to maintain a high level of pedestrian activity and where they want to preserve a continuous pattern of retail shops along the street. The Orlando code requires that parking garages on designated pedestrian streets and malls have "'at least 75 percent of the ground-floor frontage consisting of active uses other than parking, such as offices, retailing, services, and entertainment."' The Orlando code exempts entrances and exits from measures of a garage's ground-floor frontage. The Portland downtown code is similar, requiring that "at least 60 percent of the structure's ground-level frontage be available for retail, service, or office commercial uses."The San Diego code IS precise; it requires that the ground floor be devoted to small shops with large display windows. The Sacramento code goes further. It lists allowable ground-floor uses in parking structures and office and institutional buildings. The listincludes: 1. Retail shops selling apparel, books; cameras, fabrics, gifts, luggage, paint. plants, records, shoes, and sportinggoods; 2. Walk-in businesses like arcades, art galleries, museums, and theaters; 3. Convenience stores and shops like bakeries, candy stores, delicatessens, pharmacies, florist shops, grocery stores, and restaurants; and 4. Personal service shops like banks, barber shops. beauty parlors, repaIr stores, dry cleaners, laundromats, printing, phOlogrilphic studios, tailor shops, and travel agencies. Most codes mandnte that J. parking garage's street frontage be used exclusively for H.'tail, personal service. or convenience uses, except for the garage's entrance and exit ramps and service doonv.JYs. In many of these cities, the retail uses must occupy a significant percentage (lIp to 75 percent) of the street-level frontage, and any blank facades along the street are Iimiteu to 15-to 30-foot segments. Architectural and Functional Standards Some cities, like Bclll'\"l!c, Washingt"on, San Francisco, and Pasadena. California. have very broad, comprehensive codes for parking structures. These codes not only have aesthetic controls, they have standards for traffic safety, pedestrian safety, and parking structure operations. Pasadena'sstandards are simple but thorough: The exterior surface materials and structures of the garage must be compatible \",'it h the main structure; The location of parking structure entrances and exits must be planned so as to hu.\'e the least impact on residential streets and busy intersections; Facade length and height must be limited so as not to create large blonk walls without the benefit of architectural relief and landscaping; anu Setbacks and buffering must be consistent with what is required for adjoining properties. The Bellevue zoning codt· is similar but strt"SSCS traffic and pedestrian safety as mUlh .1S archiwctural compatibility, The design of tIle Sclwoj})()lfsc garage in Pasadena, California, was tilt? subject of 130 meetings of tile dty plamri!lg, desigH review, and cultured cultured heritage COIIlJllissiolls, (City of Pasadena, California, Puhlic Works and Transportation Deparll!1l!l1t) Bellevue has a regional shopping mall downtown and largescale office developments that generate a significant need for parking. In the downtown area, parking garages are permitted only if: Driveway openings and access lanes are minimized; The dimensions of the structure abutting pedestrian areas are minimiz.ed, except where the ground floor of gilrages is devoted to retail, service, or commercial activities; The structure exhibits a horiz.ontal rather than a sloping building line; Screening or other improvements are made so that parked. vehicles are shielded from view at each level of the parking structure; Developers include safe pedestrian connections between the parking structure and the principal use; and Structures comply with other setback and landscaping requirements. TheSan Francisco downtown code for parking structures goes much further than the Bellevue or Pasadena codes. It controls the appearance, location, and function of structures alld regulates lhe price structure.of parking. The object behind regulating the ccst of parking is to encomage shortterm parking used by shoppers and to discourage long-term (employee) parking. According to the city code, the city planning commission is responsible for the review of any major parking slrUclure (i,e .. a garage that is not classified as accessory parking). The code includes the following provisions. Parking structure'S must be highly accessible from freeway ramps and major thoroughfares; The location of structures must beronvenient to 􀁣􀁯􀁮􀁣􀁥􀁮􀁾􀀠 trated commercial development 􀀼􀁬􀁲􀁻􀀧􀁾􀁬􀁓􀀻􀀠 -30 I :\bovd Sall FmHn'sro's Lomhanl Stl't't,·t 8tlmgt' fils il1h, the r-oIhric of tilt' I1ci:»:lJltn),;lood" 51ttlWllitcfe if; fIll' 􀁬􀁊􀀯􀀱􀁉􀁤􀁾􀀧􀀠HW$/t '1'1.'t'lliJlg 1f::ot'ln/cs, l1le.: /JOllS./IIS StiJill. }J/I()t.\'<;nlI1ilt'rl Ilh')(lw) Tirt' diy's PIlt!SIIWIIII! 5qtHl1!' 􀁕􀁊􀁬􀁬􀁬􀁴􀀧􀁲􀀺􀁾􀁉􀀧􀀨􀁬􀁬􀀯􀀱􀀱􀁤􀀠,,>!lfrtl,'\<" l':tilf 111 /0(,0, is ftlJ'Jlt'ti fly II plll,fic 􀁾􀁬􀁴􀁦􀁲􀀱􀀬􀀠that i" the cCIi/er of 􀁾􀀺􀀬􀀠.. d lift' ill CI,/llI/fOUI/L (Pnrhitl,,\ All/lml'll,v llf !flc Cilp wId C.'Wlt,1I of SHII Fmndscp) The design of entrances and exits must minimize conflicts with pedestrians; Ground floors must maintain the retal! continuity of streets; T raffk operations must minimize conflict with other forms of transit; and The fee parking structure must encourage short-term parking and discourage long-term (employee) parking. The city actually establishes limits on the fees for shortterm parking and discourages discounted parking rates for long-term, weekly, monthly, or other time-spedfic periods. Generally, the rate for short-term parking may not be higher than the hourly rate for long-term parking. Exceptions to the limits on discounting weekly and monthly fees are granted for parking garages serving downtown residential properties. " .... , 􀀮􀀢􀀬􀀮􀀺􀀮􀀮􀁆􀁾 􀀠 31 􀁇􀀼􀁩􀁾 '-'-'--; 'Tr.1;J(.. COJUn-ti( IVl /i."L {trv Q-nd"t 􀁏􀁃􀁌􀁕􀁾􀁉􀀠 B:(jO-IJ -n__􀀢􀀬􀁾􀁾􀀠 FIRE DEPARTMENT (214)450-7200 FAX (214)450-7208 Po!>! Office Box 144 Addison, Texas 75001 4798 Ailport Parkway MEMORANDUM January 4, 1996 TO: John Baumgartner, Director/City Engineer FROM: Gordon C. Robbins, Fire Prevention Chief SUBJECT: Addison Circle -suspended lighting over mews Several weeks ago I attended a meeting at which the possibility ofsuspended lighting was discussed. My understanding at the time was that cables with light fixtures would be suspended over the mews between the buildings at 75-foot intervals and at a height greater than 20-feet above the street. Yesterday I learned the proposed design also calls for cables to be suspended longitudinally down the middle ofthe mews, connecting each cable suspended between the buildings. As you know, we have serious concerns about access to the buildings in the area due to the narrow width (24') of the mews and the possibility of parked cars and other other obstructions. And, while we are prepared to work within a 24' x 75' "box" as I originally understood it; we believe the proposed design with the additional cable (a 12' x 75' box) would render our aerial firefighting equipment virtually unusable. We are therefore opposed to it. Ifyou have any qUj:lstions, please contact me at ext. 7220 Thank you. .". .' TOWN OF ADDIsoN PUBLIC WORKS To: ,Andl I 00.)< Ie ( I From: John Baumgartner, P.E. '. Director j I I CompanY:tj1J /it Zo 110 (5 Phone: 214/450-2886 FAX: 214/931-6643 FAX#: 37/·-0757, 16801 Westgrove Date: f J 41 G)iR P.O. BoX 144 . J I Addison, TX 75001 # of pages (including cover): .'iJJ DOriginal in mail DPer your request DFYI Dcan me . Comments: ." ":" TOWN OF ADDIsoN PuBLIC WORKS To: Bn.i 0 Or No...;I From: John Baumgartner, P.E. 'II' D '. '. Director companY:LQlurn hilS :rea 􀁾􀀭􀁨􀀴􀀠TrusT Phone: 214/450-2886 n 0 FAX: 214/931-6643 FAX #: 􀀮􀀮􀁬􀁃􀁦􀁾􀀠 -SI2Q 16801 Westgrove. Date: I) 41 G) lo -'--___ P.O. Box 144 Addison, TX 75001 # of pages (including cover): ,'.().J Doriginal in mail Dper your request DFYI DCall me ' Comments: " "." "."" . , TOWN OF ADDIsoN PuBucWORKS To: Catmpo )1oca n From: John Baumgartner, P.E. c '. Director Company:__________ Phone: 214/450-2886 FAX: 214/931-6643 FAX#:---16801 Westgrove. Date: /!4/q(o P.O. Box 144 # of pages (including cover): .. 􀁾􀀠 Addison, TX 75001 DOriginal in mail DPer your request DFYI DCali me . Comments: .' 0;;' •• ','. 32 TRANSACTION REPORT FOR HP FAX-700 SERIES VERSION: 01. 00 􀁾􀁁􀁘􀀠NAME, SERVICE CENTER DATE: 04-JAN-96 􀁾􀁁􀁘􀀠NUMBER, 9316643 TIME: 15:06 D8I.E TIME REMOTE FAX NAME AND NUMBER DURATION 2G RESUI T DIAGNOSTIC 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 14,45 S 386 0938 O:03:21 8 OK A7384010016C 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 14,51 S 214 871 0757 O,01 :28 3 OK 563340100198 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 15,46 R 2145571552 O:OO:50 2 OK 663113001100 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 15:53 R 386 0938 O:00:54 2 OK A7381300116C 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16:01 R 214 637 4905 0:01,17 3 OK 663813001100 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16: 14 S 214 631 8428 O,OO,43 2 OK 6638401001A4 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16,31 R 0:02,39 6 OK 663813001000 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16,44 S 3850396 O:OO,57 2 OK 55334010006A 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16,46 S 1 214 991 2740 O:00,56 2 OK 66384010019E 􀁾􀀳􀀭􀁊􀁁􀁎􀀠 16,55 S 214 701 0840 O,00,41 1 OK 66384010016C )3-JAN 170137 R 1 O,00,56 1 OK 553113001100 )3-JAN 􀁾􀀴􀀭􀁊􀁁􀁎􀀠 19,15 R 07,47 R O:05,OO 0,00: 11 12 OK 663813001100 ° ERROR 510551112001000 M-JAN 07:55 S 512 719 0262 O:01 ,00 2 OK 663840100188 )4-JAN 07:57 R 2149607684 0:OO:38 1 OK 653813001100 )4-JAN 09,07 S 214 387 0350 0,01 :47 2 OK A7384010016C M-JAN 09: 15 S 855 0219 O,03:28 8 OK 563340100198 )4-JAN 09:31 S 386 0938 0:OO:28 OK A7384010016C M-JAN 11,34 S 385 0938 O,OO: 12 1 ERROR 030A7384010016C M-JAN 11 :36 S 386 0938. O,OO:52 2 OK A7384010016C 34-JAN 11 :41 S 2149607684 O,00:42 2 OK 65384010016A M-JAN 11 :44 R 386 0938 O:00:36 1 OK A7381300116C M-JAN 11 :52 R 817 488 8845 O:04:33 9 OK 663813001100 )4-JAN 12:22 S 8174812886 O:OO:OO ° NO ANS 423684740000000 M-JAN 13:11 R O:14:55 25 OK 563113001000 M-JAN 13:26 R O:01 :34 2 OK 5A3313001080 )4-JAN 13:39 R 214 891 5119 0:01 :25 2 OK 563113001108 34-JAN 14,26 S 386 0938 0:OO:27 1 OK A7384010016C )4-JAN 14,33 S TU ELEC 7916706 0,01,03 1 OK 664848180098 )4-JAN 14:36 S 2149607684 O:OO:52 2 OK 65384818816A M-JAN 14:40 S 855 0219 O:00:51 2 OK 563340180198 34-JAN 14:46 S 214+770+5129 O,OO:46 2 OK 663840108192 S=FAX SENT R=FAX RECEIVED I=POLL IN(FAX RECEIVED) O=POLLED OUT(FAX SENT) June 8,1995 Mr. John Baumgartner Director of Public Works Town of Addison PO Box 144 16801 Westgrove Addison, TX 75001 Dear John: I have included two articles from the Transportation and Traffic Engineering Handbook published by the Institute of Transportation Engineers. I am still looking for some articles that were published a few years ago in our transportation engineers periodical, the fTE Journal. The information in the ITE Journal concerned practices in Great Britain and may or may not be useful. I may bring to your attention that there are several concerns that should be considered before installing a roundabout, also known as a traffic circle or a rotary intersection. 1. The first concern is the tremendous amount of right of way that may be required to properly design and install one in an area other than in a residential subdivision. You may have been familiar with the circle at Loop 12 and Harry Hines in Dallas, or with the circle at Camp Bowie Boulevard and Alta Mere Drive in Fort Worth. Both these circles required many acres of land. 2. Second, access around a traffic circle is severely restricted. Obviously no driveways can be located inside the circle, but driveways must be located away from the entry and departure legs of the circle for it to operate safely. This is extremely detrimental to property owners adjacent to the circle. 3. The larger the traffic volumes, the larger the circle must be. Ooce traffic volumes exceed 3000 vehicles per hour (note "ROTARY INTERSECTIONS") the level of service severely deteriorates. Also, the roundabout should be used where there are roughly equal traffic volumes on all legs of the intersections, and where turning movements, both right and left, are high. The intersections are very low speed because of the required weaving and turning traffic. They also will cause delay in instances where volumes are higher and cars will stack on the adjacent streets waiting to enter the circle. Very briefly, that's an overview. Have your traffic engineer perform a very detailed study and analysis before agreeing to install one. They mayor may not work for you. Sincerely, J:I.,. Don Penny, P.E. 3ar;()""··,J.:::.:--.;:r 􀁾􀁾􀀺􀀵􀀬􀀺􀀼􀀻􀀧􀁡􀁴􀀶􀀧􀁳􀀬􀀠 i',C 􀀵􀀢􀀻􀀳􀀵􀀶􀀺􀀿􀀺􀀺􀁟􀀢􀁾􀁈􀀰􀀮􀁪􀁃􀀻􀀠 :3c..rle :99 * C.:.as, 􀁔􀁾 .. 2S 􀀷􀀵􀀲􀀧􀀺􀀺􀁇􀂷􀁩􀀲􀁩􀀧􀀺􀀺􀀧􀀩􀀹􀀹􀁪􀂷􀁬􀁾􀀿􀁃􀁏􀀢􀁆􀁡􀁾􀀬� � 12L':,';?I)-"?261 Memorandum TO: John Baumgartner Town ofAddison FROM: Gary Jost DATE: January 5,1996 SUBJECT: Addison Roundabout -Additional comments We have completed our review of the sensitivity analysis completed by Ourston and Doctors and design plans prepared by Huitt-Zollars for the proposed Addison Roundabout This memorandum presents our findings. Sensitivity Anah"'· Ourston and Docl : based on 50 percent and 85 percent confidence levels ercent confidence level, this means that one can be 8: ;: greater than the calculated values. Based on the un< mdabout in North Texas, we would recommend that : ,culating operating conditions of the planned roundab It should also be e transportation profession regarding the most approp ,em roundabouts. The Transportation Research Board :nt capacity analysis teclmiques teclmiques and develop a new I ibis committee, chaired by Mr. John Zegeer ofBarto .elude a recommended procedure for analyzing mode /The sensitivity analysis reports that at the 85 percent confidence level traffic volumes can be increased, from volumes originally projected, by 4 percent in the A. M. peak period and 11 percent in the P.M. peak period while still maintaining a level ofservice D. This suggests that the current design is highly sensitive to small increases in traffic volumes. With an II percent increase in traffic volumes, and assuming that 10 percent ofdaily traffic occurs during the P.M. peak hour, one could estimate that the effective capacity of Quorum Drive, assuming 10,000 vehicles per day (vpd) on 1 􀁾􀀠 􀁾􀁐􀁁􀁆􀀡􀁓􀁏􀁎􀁓􀀠 Mildred, would be less than 30,000 vpd. Of particular note is the comparison ofaverage and maximum queue lengths between the original projections and the maximum volumes that can be accommodated at Level ofService D. Tables 1.0 and 2.0 present this comparison for the A.M. and P.M. hours, respectively. Table 1.0 Average and Maximum Queues A.M. Peak Hour ApPROACH LEG A YERAGE QUEUES (YEH) OruG. LOSD MAXIMUM QUEUES (YEH) ORIG. LOSD , i NB Quorum 0 1 1 1 WB Mildred 1 1 I 1 SBQuorum 17 30 35 69 EB Mildred 4 5 6 9 Table 2.0 Average and Maximum Queues P.M. Peak Hour ! ApPROACH LEG A YERAGE QUEUES (VEH) MAXIMUM QUEUES (YEH) OruG. LOSD OruG. LOSD I NB Quorum 4 12 6 25 WBMildred 5 30 10 57 SBQuorum 1 1 1 2 EB Mildred I 2 2 3 As shown in these tables, average and maximum queues increase significantly with very little increase in total volume entering the roundabout. Based on the sensitivity to small increases in peak-hour volumes identified in the analysis conducted by Ourston and Doctors, it is our recommendation that the design of the planned Addison Roundabout be analyzed further to provide more stable conditions at these anticipated volumes. 2 L OTHER DESIGN CONSIDERATIONS Parking On -street parking along Quorum and Mildred should be restricted within 150 feet ofthe roundabout on the departure legs ofthe roadways to provide adequate sight distance. Paving Typical Section The typical section for Quorum Drive specifies a full sawcut with existing steel to remain. The full depth sawcut will also cut the steel. If a full depth sawcut is desired, steel dowels will need to be drilled and inserted into the existing concrete pavement. Signing. and M.a rkings • The stop sign at Witt Mews and Mildred should be moved behind the barrier free ramps. • The no parking signs on Mildred appear to conflict with the paving plans. • Ifpedestrians are to be restricted from entering the roundabout island, then "No Pedestrian" signs should be installed in the island. • All discussions to date regarding pedestrian crossings at the roundabout have indicated that the crossings should be located one to two vehicles behind the yield line. This needs to be reflected on the plans. • Addison has typically utilized pavement markers rather than striping for lane delineation. • Advance warning signs for the roundabout should be provided. • Additional signs (i.e. chevrons) identifying the roadway curvature are recommended. Miscellaneous • There appears to be an abrupt change in crossfaIl on the north side of the roundabout at QUorum. • Loading and unloading areas should not be allowed in the area ofthe roundabout. Ifyou have any questions, please do not hesitate to call. 3 TOWN OF ADDIsoN To; {3;u :0 ,4 rlr Df!.At.,.:rr 􀁬􀀮􀁏􀁃􀁁􀁩􀀧􀀷􀁾􀀠 LAST TRANSACTION REPORT FOR HP FAX-700 SERIES VERSION. 1211.00 '"'AX NAME. SERVICE CENTER DATE. 27-DEC-95 '"'AX NUMBER. 9316643 TIME. 15.45 DAlE liME REMOTE FAX NAME AND NUMBER DURATION El:a RESUI T DIAGNOSTIC 27-DEC 15.37 S 855 121219 121.00.47 2 OK 5633412111210198 S=FAX SENT O=POLLED OUT 1000 0 0: (3 800 600 400 200 \ \ ..􀁾􀀠Multi-lane circulating ttow \' \ == 1\ 1\ \ \ f\ i\ 1\ \ '\ \ '\ \ 'I '\ \ ! "". "\ Single lane ____ ""i circulating !low "-"! "\. " 􀁾􀀠 '<: '" "I " '-.. o 200 400 600 800 1000 1200 1400 1600 1800 CAPACITY PER ENTRY LANE Q •. ..../n. (veh/hr) ROUNDABOUT CAPACITY FIGURE 3.2 11 8 7 6 .5 4 3 /i //I II/!lli 20 0' ,'!"£ . 􀁾􀀠 ...I 10 W 0 9 0 E; W ::l w ::l 0 W 􀁾􀀠 a: W 􀁾􀀠 g oo 00 8 ... 00 '" :! 􀁾􀀠􀁾􀀠 CIRCULATING FLOW a; (veh/hr) Q& -Circulating flow (vehlh) 9!' -Entry volume per lane (veh/h) n. 't -Ctitical acceptance gap -4 sees To z:-Follow-up headway" 2 sees tc -Minimum heac:tway for circulating traffic -2 sees AVERAGE QUEUEING DELAY TO VEHICLES ENTERING SINGLE LANE CIRCULATING FLOW ROUNDABOUTS FIGURE 3.3a 13 /'/ 10 􀁾􀀠 09 i? '"z 0.' \! 􀁾􀀠 07 '􀁾" 􀀠 􀁾􀀠5 0.6 􀁾􀀠 0 􀁾􀀠 􀁾􀀠 z􀁾 􀀠 0.' -w "fi wz 0' 􀁾􀀠 􀁾􀀠 0 z 0.3 Q Ir 􀁾􀀠 0.' 0 '􀁾" 􀀠 0.' /1//'" Song,&e 1IIlne_ 􀁾􀀠 .....-􀁾􀀠 I .... l7 7 ! 􀁾􀀠V'-􀀧􀁾􀀢􀀢􀀧􀁉􀀠 P , J 7 /I J PROPORTION OF ENTERING VEHICLES WHICH STOP AT ROUNDABOUTS FIGURE 3.4 TABLE 3.1a GEOMETRIC DELAY FOR STOPPED VEHICLES Approach Speed V, (km/h) Negoliation Speed through Roundabout Vo (kmlh) 20 40 km/h D (m) 60 100 140 180 20 60 kmlh 60 0. (m) , 100 140 1801 I 20 DELAY IN SECONDS 60 80 kmlh 0. (m) 100 140 180 20 60 100 kmlh D (m) 100 140 180 15 10 19 23 20 8 15 22 18 25 7 12 17 .10 15 30 7 9 13 18 ·10 13 35 7 7 10 14 18 10 10 40 10 10 45 10 10 50 10 10 26 21 18 22 15 19 23 12 15 19 10 12 15 10 10 10 17 15 13 13 13 13 13 13 26 22 19 17 14 13 13 13 29 25 21 26 19 23 27 16 19 23 13 16 19 13 13 16 20 18 17 17 17 17 17 17 30 25 22 20 18 17 17 17 33 28 25 30 22' 26 30 ' 20 23 27 17 20 24 17 17 20 where D. = distance around roundabout (m) 15 3.4 SAFETY OF ROUNDABOUTS 3.4.1 The safety performance of roundabouts has been documented in a number of Australian and UK studies. "Before" and "after" type accident studies carried out at intersections involving a wide range of site and traHic conditions at which roundabouts have been constructed, indicate very significant reductions in casualty accident rates. Details of the results of some studies carried out in Victoria and in the United . Kingdom are given in Appendix A. 3.4.2 . The following tabulation (Table 3.2) illustrates the result of comparative studies' carried out in Victoria22. TABLE 3.2 TYPICAL CASUALTY ACCIDENT RATES FOR DIFFERENT INTERSECTION TYPES IN VICTORIA Intersection Type Mean Casualty 90% Confidence Accident Interval For Rate The Mean URBAN INTERSECTIONS, MODERATE TO HIGH VOLUMES T-Intersections -Unsignalised -Signalised Cross-Intersections -Unsignalised14 -Signalised Multi-leg Intersections -Signalised Roundabouts (high volumes) Roundabouts (low volumes) 1.5 1.4 2.4 1.7 3.2 0.8 0.4 ( 1.3 -1.7 1.2 -1.6 2.1 -2.7 1.6 -1.8 2.8 -3.6 0.6 -1.1 0.1 -1.0 Note: See Appendix A for definitions 3.4.3 The good safety record ofproperly designed roundabouts can be attributed to the following factors: (a) The general reduction in conflicting traffic speeds (desirably limited to less 17 PERFORMANCE OF ROUNDABOUTS 3.6 ENVIRONMENTAL EFFECTS 3.6.1 Roundabouts can offer considerable scope for environmental enhancement and are sometimes favoured over other forms of intersection treatment in environmentally sensitive areas. The central island can be landscaped and planted provided: (a) the treatment does not block any of the sight triangles (refer Section 4.2.5); (b) any planting and landscaping will yield to out-of-control vehicles and not be a hazard; (c) the treatment does not constitute an unnecessary distraction to drivers. Planting can be used to discourage pedestrians from crossing at undesirable locations. 3.6.2 Compared to traffic signals, roundabouts usually operate with generally reduced queue lengths and shorter average delays. This results in: less air and noise pollution; lower fuel consumption; less parking restrictions; better access to private driveways. In addition, the use of a roundabout eliminates potential traffic safety and disruption problems associated with the malfunction of traffic signals. 3.6.3 Roundabouts can be used on local streets to discourage high traffic speeds and intrusion by very large vehicles. Provisions for emergency and service vehicles need to be considered in the design of these roundabouts. 3.7 PEDESTRIANS AND CYCLISTS AT ROUNDABOUTS 3.7.1 In most circumstances roundabouts can be designed to provide satisfactorily for pedestrian movements at an intersection. 3.7.2 Preliminary information suggests that roundabouts are at least as safe for pedestrians as other forms of intersection control. This is probably because pedestrians are able to cross one direction of traffic at a time by staging on the splitter islands. Furthermore, vehicles are travelling at slow speeds and the pedestrians cross with care because, unlike traffic signals, roundabouts do not give positive priority messages to pedestrians. Particular groups of pedestrians, such as the elderly or children may. however, find traffiC signals a more secure control for crossing a road. 19 4 GEOMETRIC DESIGN OF ROUNDABOUTS 4.1 GENERAL The principles of roundabout design as they apply to urban arterial and rural intersections are similar. and consequently will be considered together. Because of the high traffic speeds in rural areas. it is much more important to achieve the criteria designed to slow down traffic entering the roundabout. Fortunately. in urban areas. where the cost to achieve ideal standards in respect to speed control is higher. the consequences of not doing so are less critical. In local streets because of constraints such as cost and space and because of differing objectives. design standards may be quite different to those applicable to arterial roads. 4.2 URBAN ARTERIAL AND RURAL ROUNDABOUTS 4.2.1 Design Speed and Deflection Through Roundabouts. Adequate deflection through roundabouts is the most important factor influencing their safe operation. Roundabouts should be designed so that the speed of all vehicles within the intersection will be less than 50 km/h. This is done by ensuring that through vehicle paths are significantly deflected by one or more of the following means: (i) provision of a suitable size and pOSition of central island; (ii) introduction of a staggered or non-parallel alignment between any entrance and exit; (iii) pOSition. shape and size of approach splitter islands. The desired design speed is obtained if no vehicle path (assumed 2 metres wide) has a radius greater than 100 metres. This degree of curvature corresponds approximately to 50 km/h with a sideways force of 0.2 g. The required vehicle 21 ,. This view illustrates the deflection of traffic through a rural roundabout. The design speed through roundabouts can be calculated from the formula: V2 = 127 R (e + f) [4.1J where V is speed in km/h R is the maximum path radius of a vehicle in metres (see Figure 4.2) e is the superelevation in m/m (negative if the fall is from the central island) f is acceptable coefficient of sideways friction between vehicle tyres and road pavement For roundabouts, values of f ranging from about 0.2 at 50 km/h and about 0.3 at 25 km/h should be used. Designers should interpolate for speeds between 25 km/h and 50 km/h. 4.2.2 Central Island. Central islands should preferably be circular as changing curvature of the circulating roadway increases the driving task demand. However, oblong or other shapes may need to be adopted to suit unusual site conditions. The size of the central island is determined principally by the need to obtain sufficient deflection to reduce through vehicle speed. If this can be achieved by other means, there is no theoretical limit on the minimum size of the central island. However, the larger the central island the easier it is for entering drivers to determine whether vehicles already on the circulating roadway are turning right or passing straight through. With small central islands, particularly where high approach speeds are preva-. lent, adjacent conflict areas tend to be inadequately separated and this increases doubt for entering vehicles. Larger central islands are usually necessary to clearly separate conflict areas at multi-leg intersections and they generally improve driver recognition of the form of intersection treatment. 23 􀁾􀀧􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭 In this particular case: Rz = 12 m, Table 4.1 gives a width of 10.3 m Rl = 50 m, Table 4.1 gives a width of 12.6 m Therefore the circulating width would be 12.6 m. TABLE 4.1 WIDTHS REQUIRED FOR VEHICLES TO TURN ONE, TWO OR THREE ABREAST Turning Desirable Turning Width required for Radius R(m) one articulated one articulated one articulated vehicle vehicle vehicle (m) plus one plus two passenger car passenger cars (m) (m) 5 7.6 11.7 • 8 7.1 11.2 • 10 6.7 10.8 " 12 6.5 10.3 " 14 6.2 10.1 • 16 6.0 9.9 " 18 5.9 9.7 " 20 5.7 9.6 13.5 22 5.6 9.5 13.4 24 5.5 9.4 13.3 26 5.4 9.3 13.2 28 5.4 9.2 13.0 30 5.3 9.1 12.9 50 . 5.0 B.8 12.6 100 4.6 8.4 12.2 "Three lane wide turning paths are most unlikely to occur on a turn radius less than 20 m. Analyses may be required for each section of circulating roadway. In some· cases, a roundabout may have a varying circulating roadway width. Truck turning templates should also be used to ensure that trucks can negotiate the roundabout. In some instances it may be appropriate to narrow the widths slightly to achieve an adequate deflection. 25 An example of where provision has been made for an overdimensional vehicle to turn from north to east (and vice versa) is shown in Figure 4.3. 4.2.4 Splitter Islands, Entrance and Exit curves 4.2.4.1 Splitter islands should be provided on all roundabouts installed on arterial and collector roads in rural and urban areas. They provide shelter for pedestrians, guide NOTE: shaded area defines 0.0. vehicle fuming pafh tII1d should be sfrenglhened. -------,;7"'--..... Soil !Hled '--------Concrete (or olner mad bearing material) ROUNDABOUT CROSS·SECTION A·A PROVISION FOR OVER DIMENSIONAL VEHICLES FIGURE 4.3 27 Straight departure o :'n" 1.2m down to 􀁏􀀮􀁾􀀳􀁭􀀡􀀡􀁮􀀮􀀬􀀮􀀮􀀮􀀮􀀠 ·O.6m """"ptebie on amall islands )1 TYPICAL ROUNDABOUT ENTRANCE/EXIT CONDITIONS FOR URBAN AREAS· FIGURE 4.5 ·4.2.4.2 Entry and Exit lane widths should be determined using vehicle turning templates. Generally. lane widths will fall within the range 3.4 m to 4.0 m. Exceptions are for kerbed single lane entrances and exits where a minimum of 5.0 m between kerbs is usually provided to allow traffic to pass a disabled vehicle. 4.2.4.3 On high speed roads, the splitter island should. if possible. extend across the whole of the approach lanes as seen by the approaching driver. This is illustrated in Figure 4.6. In high speed areas the splitter island should also be relatively long (ideally about 60 m) to give early warning to drivers that they are approaching an intersection and must slow down. The lateral restriction and funnelling provided by the splitter island encourages speed reduction as vehicles approach the entry point. Kerb and channel channel should be placed on the left-hand side of the approach road for at least half the length of the splitter island to strengthen the funnelling effect. Kerbs should always be provided on the splitter islands, central islands and outer edge of pavement to improve delineation and prevent corner cutting. 4.2.4.4 The approach curves to roundabouts should be the same radius or smaller than the radius of the curved path that a vehicle would be expected to travel through 29 --.------------------------------------------------------a good view of both the splitter island and the central island. Adequate stopping sight distance should be provided, preferably to the 'Give Way' lin!"s and, at an absolute minimum, to the nose of the splitter island. Table 4.2 indicates the required stopping sight distances. This Table is based on Table 4.1, Interim Guide to the DeSign of Intersections at Grade7. To enhance the prominence of the roundabout. the kerbs on both the splitter island and central island should be light coloured or painted white. As with other types of intersections, it is better to pOSition a roundabout in a sag vertical curve than on a crest. TABLE 4.2 STOPPING SIGHT DISTANCE Approach Speed (km/h) . Stopping Distance· (m) 40 45 50 60 60 80 70 100 80 120 90 140 100 170 110 210 120 250 • measured 1. 15m to zero Criterion 2 A driver, stationary at the 'Give Way' line. should have a clear line of sight to approaching traffic for a distance representing at least four seconds of of travel time. Since, as covered in Section 4.2.1. the speed of all vehicles within the intersection should be constrained to 50 km/h or less. the corresponding sight distance to vehicles approaching from the right should be at least 50 m. measured from the pOSition of the driver about 5 m from the 'Give Way' line. This is illustrated in Figure 4.7. Criterion 3 It is also desirable that drivers approaching the roundabout are able to see other entering vehicles well before they reach the 'Give Way' line. The 40 m-50 m sight 31 GEOMETRIC DESIGN OF ROUNDABOUTS CRITERION 2 Provide adequate sight distance for drivers to detect acceptable ........ gap. (essential) "" " SIGHT DISTANCE REQUIREMENTS FIGURE 4.7 Where a roundabout is proposed, special care should be taken to ensure that the design is in accordance with the standards listed in Sections 4.2.1 to 4.2.6. In particular, sufficient deflection for through traffic should be achieved. Generally, a cheap solution which does not require roadworks encroaching onto existing nature strips and/or the median will not be possible. Figure 4.8 is an example of a roundabout designed to adequate standards for·a sub-arterial road crossing an arterial road with a wide median. 33 CRITERION 1 Provide stopping distance as per Table 7. (essential) o..,. CRITERION 3 Provide sight triangle to allow comfortable gap recognition. (desirable) a L Where kerblines are to be built out on approaches to roundabouts, special care should be taken to ensure that adequate delineation is provided, particularly in instances where there are no parked vehicles on the approach. A suitable treatment using linemarking, raised reflective pavement markers (rrpm) and semimountable kerbs is shown on Figure 4.9. . t ! in 10 (max) ••__ . _r One-way hazard boards Raised rellective pavement markers o· 99 30m ROUNDABOUT AT T -JUNCTIONS FIGURE 4.9 Footnote: The layout has been devised with the objective of providing a safe, well delineated, but sufficiently deflected path through the roundabout, while limiting the amount 01 parking that has to be restricted. State Road Traffic Regulations generally restrict parking close to the intersection. When vehicles are parked close to the intersection, there is no difficulty in de11ecting vehicles away from the kerb on approach to the roundabout. Thus, it is acceptable to allow vehicles to park on top of delineating devices. 35 might restrict sightlines between conflicting traffic or pedestrians, or create an unnecessary hazard. Alternative fully kerbed island /Altemative comer splay for larger central island \ Umned height landscaping' Safety bar island -......... 􀁩􀀬􀁬􀀮􀀮􀀮􀁾􀀮􀀻􀀮􀀻. .. .......,,' ......... Semi·mountable kerb Additional paved area 􀀺􀁦􀁾􀁾􀁾􀁾􀀠 (to cater for large vehicle path). 􀀺􀁾􀀺􀀧􀁻􀀻􀀠 One·way chevron hazard markers 􀁾􀀠.sa foptional) . 􀀭􀀻􀁾􀁾􀀮 .. 􀀬􀀬􀁾􀀬􀁾􀀺􀀮􀀺􀀬􀀠... //􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀀭􀀭􀀭􀀭􀁾􀀺􀀠 ,􀀾􀀺􀁯􀁯􀁾􀀠 15m \ ,,, 􀀮􀀺􀀮􀀧􀀭􀀭􀀭􀀺􀁟􀀭􀀭􀀭􀀭􀀭􀁴􀀭􀀭􀀢􀀧􀀺􀀮􀁾􀀧􀀠'., LOCAL STREET ROUNDABOUT , 􀀮􀀧􀀡􀁾􀀺􀀬􀁾􀀮􀀬􀁣􀁾􀀧􀀻􀀻􀁾􀀮􀀻 FIGURE 4.10 .... 􀀭􀀮􀁾􀁾􀁾􀀠 p, 37 􀁾􀀠 .. " J' 1" 5 PEDESTRIAN AND BICYCLE CONSIDERATIONS 5.1 PEDESTRIANS In the planning and design of roundabouts, special thought should be given to the movement of pedestrians. Section 3.7 discusses some aspects of the performance of roundabouts in respect to pedestrians. In respect to geometric design, the provision for pedestrians does not differ greatly to that required for other intersection treatments, however, certain roundabout designs, particularly large roundabouts, can result in greater walking distances, and thus inconvenience, for pedestrians. Some designs can also result in doubt with regard to priority between pedestrians and vehicles which may result in minor problems. Pedestrian crossing lines should not be painted on the entrances and exits of roundabouts. It is important not to give pedestrians a false sense of security but, rather, to encourage them to identify and accept gaps in traffic and to cross when safe to do so. Notwithstanding this, pram crossings incorporating pedestrian refuges will generally be required. It is suggested that these crossings be provided close to the entrances and exits of roundabouts. Consideration should be given to providing priority crossings for pedestrians where pedestrian volumes are high, where there is a high proportion of young, elderly or infirm citizens wanting to cross the road, or where pedestrians are experiencing particular difficulty in crossing and are being delayed excessively. It is desirable that these crossings be placed at least 20 m downstream of the exit from the roundabout. This will reduce the probability of vehicles delayed at the pedestrian crossing queueing back into the roundabout and "blocking" of the whole intersection, causing potential hazards associated with rear-end collisions. It may be desirable that fencing be installed to ensure that pedestrians use the crossing facility provided. 39 6 LINEMARKING AND SIGNING 6.1 GENERAL To ensure effective and safe operation of roundabouts, high standards of delineation and signing should be provided. It is important that consistent arrangements of signs and other devices be provided to enhance driver expectation. 6.2 LlNEMARKING The linemarking used at the 'Give Way' point consists of a series of 600 mm x 300 mm white stripes separated by gaps of 600 mm. This line is painted on the approach to the roundabout, generally parallel with the circulating roadway. Where there are two or more traffic lanes on a particular approach the roundabout "Give Way" line should be angled so that drivers in vehicles in the left lane can see past adjacent vehicles on their right. There should be no painted lines across the exits from roundabouts. Lane lines delineating circulating lanes within the roundabout should not be provided because they may confuse rather than help drivers in the performance of their task of negotiating the roundabout. They may also mislead drivers into thinking that right turn manoeuvres should be made by circulating around the outer lane of the roundabout. Lane direction arrows should not be used on the approach to the "Give Way" line, except when an exclusive left turn lane is provided. Arrows are generally unnecessary and right turn arrows may mislead some drivers into turning right before the central island. (I.e. wrong way around the circulating roadway) Linemarking on the approach to roundabouts should be as shown on Figure 6.1. The linemarking may be emphasised by the placement of rrpm's as shown. 41 I Regulatory signs should be placed on each approach to the roundabout. The sign should be located on the splitter island near the 'Give Way' line. For roundabouts with mUlti-lane approaches, a second sign should be positioned on the left hand side to reinforce the first one. If a raised splitter. island is not provided on local street roundabouts, the sign should be placed on the left hand side. 6.3.2 Splitter Island and Central Island Signing Standard KEEP LEFT signs should be provided on the approach nose of splitter islands. On small splitter islands it may be possible to combine the KEEP LEFT sign and the regulatory sign on one pole. For large splitter islands, hazard boards are desirable to emphasise the curved approach into the roundabout. Signposting at a roundabout. It may also be desirable to place a two-way hazard board on large splitter islands where the circulating and departing roadways fork. These hazard boards should be low mounted so that they do not impair sight distance across the island. island. Figure 6.3 shows suitable arrangement. 43 An example of an advance direction sign for a roundabout. Dimboola o Horsham r r ,I i DIAGRAMMATIC ADVANCE DIRECTION SIGN FIGURE 6.4 (b) Intersection Direction Signs: Generally, it will be necessary to supplement advance direction signing with intersection direction signs at the roundabout. These sigris are best placed on the left-hand side of the circulating roadway ! at each exit from the roundabout. Where an appropriate location cannot be found in this area, signs may be placed on the splitter island at a height such that visibility for entering traffic is not obscured. The mounting height of such signs will depend on the vertical geometry on the approach to the roundabout. 45 ....,....... M,,,.··_A....... Locale-PJn befween 113Qm and' 250m 􀁦􀁲􀁯􀁭􀀺􀁾􀁬􀁊􀁴􀀠 NOTES: t.ocale SIgn between 180m and 250m a The use of the tegUiatory $ign will depend from roundaQoul =--...... on indMduaJ Stete j)t'8CfiCe$ $S per 􀁾􀀧􀀠 . I2J Secbon 6.3.1 CC:C" .... Fat tWSMuntnee signs mounted on the Mttt Show atTOW on nOht hand Side. if sign mounted on nght show arrow on ;eft hand $Jde. ........􀁾.•...". .. 'WHim" ICI:IOIIIIJJ " lr2::.mJ t:.C:C:" Cc::a':l /v' r::m .. -,,"'., 􀁾􀀭 .. 12i. 􀁾􀀯􀀧􀁣 􀁴􀀺􀀮􀁣􀀺􀁣􀀺􀁾􀀠 ...... , ',,"-'''iE, !.Ocate $fgn Oelween 180m and 250m from roundabout '. ",-=====""",,' . , .. Locale aign between 180m W'Id 250m from roundaboul -.-.-_ ., ,"-,,"t-_ \ TYPICAL SIGNING AND LlNEMARKING SCHEME FOR A RURAL ROUNDABOUT FIGURE 6.Sb 47 I 7 LIGHTING OF ROUNDABOUTS I I I 7.1 GENERAL The satisfactory operation of a roundabout relies heavily on the ability of drivers to enter into, and separate safely and efficiently irom a circulating traffic stream. To do this, it is important that the driver must perceive the general layout of the intersection in sufficient time. It is therefore recommended that some form of lighting be provided at roundabouts on all classes of roads. This recommendation is supported by the results of a study of roundabouts25 which showed that 87 percent of accidents involving fixed objects off the roM, occurred at night. Adequate lighting is essential for the safe and efficient operation of a roundabout at night. 49 (a) Minor Local Road/Local Road Intersection (On intersecting roads of less than 7.5 m width). One high pressure 250W sodium light could be used. (b) Major Local Road/Local Road Intersection One high pressure 250W sodium light on two major approaches; and (c) Roads of Higher Traffic Volume or Operational Problems One high pressure 250W sodium light on all approaches. In general. because of the lower level of lighting provided on the local street system, supplementary means of improving delineation, such as painted and reflectorised kerbs, low mounted hazard markers and reflective pavement markers are recommended for more important traffic routes. Figure 7.1 illustrates typical examples of fixed lighting at urban arterial and local street roundabouts. 51 J I i I I 1 j, j: . LANDSCAPING AND ROAD FURNITURE Roundabouts can offer advantages over other forms of channelisation with respect to landscaping. However, the constructing authority must ensure that the landscape design does not create a danger to road users. Structures associated with the roundabout such as kerbs, signs and utility poles should be selected or designed to minimise their adverse effect on impacting vehicles, or located clear of areas most likely to be traversed by out-of-control vehicles. In all cases, kerbs should be of the mountable or semi-mountable types and signs should be mounted on frangible posts. The landscaping should not inhibit sight distance, obscure the form of the layout to drivers, restrict the visibility of signs. or present roadside hazards in the form of large trees. boulders or planter boxes. To avoid a danger to any out-ofcontrol vehicles, the central island should not have obstacles higher than 400mm r above the level of the Circulating roadway. The central island should: r clearly indicate to drivers that they cannot pass straight through the intersection. This may be achieved through planting, landscaping or hazard boards etc. allow drivers approaching the intersection adequate sight distance, as described in Section 4.2.5. ideally prevent the passage of pedestrians. (Seats or similar attractions should not be provided). 53 9 TRIAL INSTALLATIONS 9.1 GENERAL The use of trial installations, built of removable materials, may be appropriate to verify the effectiveness of the treatment. This procedure is widely practised for other forms of channelisation. Trial installations should be used for only a limited period, desirably no longer than about three months, and not more than six months. This Section provides some guidance on the procedures to follow when installing trial roundabouts. An example of a trial roundabout installation. r 55 i APPENDIX A SAFETY PERFORMANCE OF ROUNDABOUTS RESULTS OF ACCIDENT STUDIES A.1 Well designed roundabouts have been shown to operate with a high degree of safety. In 1981, the Country Roads Board of Victoria carried out a "Before and After" study22 of 73 roundabout sites throughout Victoria to assess their safety performance. The form of control during the "before" period was either 'Give Way to the Right', 'Stop' or 'Give Way' sign controls, or in one case a police control. The sites were primarily in urban areas although some rural sites were included. The major results of the study are summarised below: (a) The casualty accident rate for all sites combined decreased by 74 percent after roundabout installation. (b) Sites were grouped according to entering traffic volumes. All groups showed a statistically significant reduction in accident rates as shown in Table A.1. (c) Minor Accidents. It is difficult to gauge the effect of roundabout installation on minor accidents in Victoria because not all property damage accidents are reported. However, there was a 32 percent reduction in the property damage accidents which were recorded at the study sites. While this is not conclusive, it would appear that roundabouts have led to a reduction in property damage accidents as well as casualty accidents. (d) Roundabouts in High Speed Areas (Le. on road with 100 km/h speed limits). In 1981 the only roundabouts in Victoria installed on high speed roads had produced very large reductions in casualty accidents. Both locations were at cross intersections formerly controlled by 'Give Way'I'Stop' signs. Table A.2 shows the improvement. The probability of the reduction occuring by chance is less than 0.001 (e) Pedestrian Safety. There was a 68 percent reduction in casualty accidents per year involving pedestrians after roundabout installation for all sites combined. This result is encouraging, but owing to the low numbers of pedestrian accidents, the reduction was not statistically significant at the 0.10 level. A.2 The results of the Country Roads Board Studies described above are consistent with other studies on roundabout safety. In particular: (a) A study26 of 31 roundabout sites in Melbourne carried out by the Road Safety and Traffic Authority which showed a statistically significant reduction in report· ed accidents after roundabout installation. (b) A study24 of 150 roundabout sites in the United Kingdom carried out by the Transport and Road Research Laboratory discussed below A.a The study24 of 150 roundabout sites in the United Kingdom indicated that: 57 Casualty accident rate = (A 101) I (2 n' V1V2 ) Where: A = number of casualty accidents in 'n' years. Casualty Accidents are defined as the sum of fatal accidents and personal inJury accidents. n = number of years V1, V2 = total number of vehicles entering the intersection on Roads 1 and 2 in 'n' years. TABLE A2 CASUALTY ACCIDENT REDUCTION RATE ACHIEVED BY ROUNDABOUT INSTALLATION AT TWO HIGH SPEED LOCATIONS IN VICTORIA (STUDY PERIOD JANUARY 1975 TO DECEMBER 1980) BEFORE Roundabout AFTER Roundabout Number of Installation Installation sites Total Total Average : Total Total Average years Casualty Casualty • years Casualty Casualty ! Accidents Accidents Accidents Accidents , Per year Per year 2 3 0 0 (including four fatal accidents) 8 39 4.9 ! 59 " f· 8.1.2 Consideration of Alternatives 􀁾􀀠 Traffic Signals or a roundabout can be considered as alternatives to' the existing arrangement. Both treatments should be analysed and compared with regard to safety, capacity and delays, parking spaces and cost. In this regard only the analysis of the roundabout is provided in detail. Analysis procedures for a traffic signal alternative may be carried out in accordance with ARRB Bulletin ARR No.123 or preferably in terms of SIMSET-2 or SIDRA-2. SIMSET·2 at this stage is more user friendly. Roundabout Alternative The critical peak hour traffic volumes were transcribed as follOWS: (Refer Section 3.2) ON 􀁕􀁾 ''"" The degree of saturation and delays for each leg of a one-lane roundabout were calculated as shown below: Leg Circulating Capacity Entry Flow Degree of Flow Per Entry Saturation (Figure 3.2) AM N S E W 227 368 65 46 1470 1270 1700 1730 36 82 434 223 0.02 0.06 0.26 0.13 PM N S E W 461 230 44 115 1160 1470 1730 1630 22 140 254 391 0.02 0.10 0.15 0.24 From Figure 3.3a the average queueing delay on each approach (AM and PM) would be about 1 ·second. This table indicates that a one-lane roundabout could easily cater for for the traffic volumes. A roundabout could also be expected to reduce the accident rate sig· nificantly at the intersection (refer Section 3.4). 65 \ Locale sIgn belween 180m and 250m 'rom roundabout Locale SHJn belween 180m ana 250m from roundabout 􀀭􀀭􀁾􀀭􀀭􀀭􀀭􀀭􀀮􀁾􀀠 "0'lfUl 􀁾􀀠 s•••••􀀧􀁾••••'.' o ; " c:c: ri LoCale sign belween 180m and 250m Irom roundabout =======" Sign between 180m and 250m; from roundabout Shaded area speciWly paWKS tor 0.0. vehicles EXAMPLE OF RURAL ROUNDABOUT DESIGN FIGURE B.2 67 ------Departure width Exit width Entry width Comer kerb radius Approach width Central island diameter Give way line Circulating roadway Inscribed circle diameter Circulating roadway width r-1--_ Splitter island ELEMENTS OF A TYPICAL ROUNDABOUT FIGURE C.1 69 I I ! SAFETY 22. CRB -Before and After Accident Analysis of Roundabouts (Inter-office ! memorandum), 1981. ! 23. CRB -Various studies reported in Inter-office memorandum, 1981. 24. Green H. TRRL Report 774. Accidents at off-side priority roundabouts with mini or small islands, 1977. 25. Lalani N. "The Impact of Accidents .. , priority junctions", Greater London Road Safety Unit -Greater London Council, December 1975, 26. RoSTA -Accidents at Roundabouts, July 1980. MISCELLANEOUS 27, Lawrence C.J.D. Roundabouts -Evaluation of the I.H.E. May 1980. 28. Marconi W. Speed Control Measures in Residential Areas. Traffic Engineer, March 1977. 29. Martin, D.J. Incremental Operating Costs of Cars at Roundabouts. TRRL Report SR 60VC, Crowthorne, 1974. 30. Swaminathon M.S., Hazel B.J. Roundabouts -A discussion paper -Traffic Authority of N.S.W. September 1980. 31. Todd K, Modern Rotaries ITE Journal July 1979. 71 " -,' y;\v DRIVE A ROUNDABOUT . . . .. ;..: " . , 't''"'" 􀀧􀀻􀀺􀀺􀀺􀀺􀀢􀀢􀀧􀀻􀀺􀀻􀀢􀀧􀁾􀁾􀀺􀀻􀀧􀁾􀁾􀀧􀁾􀀱􀀬􀀢􀁜􀀧􀀺􀀧􀀢􀀠 , '. _<','" :;, c':,,/":, 􀁾􀀢􀀢􀀠 •. ,-:'.::;,AS':you·.approach'.a roundaBout there will be;.a; ';" dashedYield'lirriitlirie_ Slow 􀁤􀁯􀁗􀁮􀁾 '.' pfep£rec (!.'''': . 'i; . ":'.:"-.,.:. .􀁾􀀺􀀠 '.' ;": 􀁩􀀺􀂷􀀧􀀻􀀯􀀺􀀺􀀺􀀮􀁩􀁪􀁾􀁾􀂷􀀬􀀠 ..􀀻􀁾􀁟􀀮􀀠􀀻􀀮􀁾􀀠 i': '.,: ." 􀀺􀀮􀁾􀀧􀀮􀀧􀀠 , ,,:' . 􀁾􀀢􀀠.. ,'".•:, .!" ...., :. ,,;" /:: ":;", :.'-'. Act, this doclimem __ ,_. ________---__________,_________ ,. ' ..'" ',.;-: bv 'calling 654-7887or 􀁴􀁨􀁬􀁯􀁾􀁧􀁨􀀠the California 1';;.; n," ,-' .:;';' ;; . Each year the Cicy receives numerous requests'tei· ... · 􀁲􀁾􀁤􀁵􀁣􀁥􀀠the traffic' congestion on streets throughout' ..;" .'. . .; · theqcy,' 􀁃􀁩􀁴􀁩􀁺􀁥􀁮􀁾􀀠also express 􀁣􀁯􀁮􀁾􀁲􀁮􀁳􀀠about:;th..􀁾􀀺􀁴􀀠 ';". >_ . safecyofche streets on which they live. In an effort to .:..... '.' . find appropriate ways to deal with .these concerns ••. :'.'._ ":"'»:' 􀀧􀀺􀀮􀁲􀁥􀁤􀁾􀁣􀁥􀀠traffic con?estion and improve safecy,'theSit}':',' .'. ;'<,Roundabouts are used throughout Europe and.in....:: "::;/:':,.":.':.. ,: several 􀁣􀁯􀁾􀁮􀁴􀁲􀁩􀁥􀁳􀀠around thi: world to 􀁲􀁥􀁤􀁵􀁣􀁾􀀩􀁮􀁪􀁵􀁲􀁹􀀢􀀧􀀻􀀧􀀺􀀺􀀧􀀠:.• ::Y .. "c I," .a.ccidents. 􀁴􀁲􀁡􀁦􀁦􀁩􀁣􀁾􀁬􀁡􀁹􀁳􀀻􀀠fuel 􀁣􀁯􀁮􀁾􀁵􀁾􀁰􀁴􀁩􀁯􀁮􀁾􀀠air pollu-, :,;'. ,":: " .• :;:;: I' -.:" .' I I Z 􀁾􀀮􀀠. I :tlon and construction costs, while lncreasmg capac-.. :' '. ";' -'. 􀀢􀀮􀁾􀀮􀀧􀁾􀁾􀀮􀀧􀀮􀀧􀀠 .._.......' _ n' .. , .". 􀀮􀀧􀀮􀁾􀀧􀀠 •.•.. ", .'. ' . :", ..... . . • 'f -.' .......' ,f.\-·,. -􀀧􀀮􀁾􀀠 '. icy. and enhancing intersection .beauty:. They have alSo...".>,-.:.',.' -,'<,"'." '--..-...: C .. ..., '-"'R" d b'" .. ,-..... 􀁾􀀠 . , '. .' . .' '. .'. ,< ...... '.", -. -.'. .-onventIon3.1' oun a out . -. · successfully been used to control traffic speeds InreSI-. ,::"-·f :<:; .•,<;;"., ....., .•. : ..... '. .., .... " -, "---" .. ' '." .' .􀁸􀀮􀁩􀁴􀁦􀁴􀀺􀁾􀁾􀁾􀁬􀁬􀁩􀁾􀀷􀀺􀀺􀀺􀁾􀁲􀂣􀀺􀁾􀀺􀁾􀀻􀁩􀁾 􀀺􀁅􀁾􀁪􀁾􀀮􀁾􀁴􀀻􀁉􀁾􀀺􀁾.􀀲􀁾􀀧􀀺􀁌􀀻􀀵􀁾􀀮􀀺􀀠I··􀁾􀀺􀀧􀀺􀀠 .::(:, 􀀺􀁜􀁉􀀺􀁟􀀬􀀮􀀱􀁜􀀴􀀱􀀺􀀺􀀻􀀺􀁾􀀻􀁹􀀮􀀠: c';,' .: . ':'. ;he'traffic circle used 􀁰􀁾􀁥􀁶􀁩􀁯􀁵􀁳􀁬􀁹􀀠;'nthls 􀁾􀁯􀁵􀁲􀁩􀁩􀁲􀁙􀀮􀁔􀁨􀁥􀀧􀀻􀀡􀀺􀀻􀀧􀁴􀀺􀁾􀀻􀀺􀀬􀀻􀀺􀀠 􀀻􀁾􀁾􀁦􀁾􀁾􀁾􀁾􀀱􀁾􀀡􀁩􀁬􀁾􀁾􀀧􀁉􀀭􀀢􀀻􀀢􀀢􀀢􀀢􀀻􀀧􀀭􀀭􀀼􀀠 -';'entry rule keeps'craffic, from locking-up' and. 􀁡􀀱􀁬􀁯􀀺􀀭􀁶􀁳􀁩􀀧􀀺􀁪􀀻􀀮􀀺� �􀀬􀁾􀀺􀀻􀁾􀀻􀀻􀁲􀁴􀀧􀀩􀀮􀀠 􀁮􀁥􀀬􀁾􀁴􀁾􀀺􀀠.>."::<' .' .:".,....:-ft·:,;·:: '.-. '-"'-;'''::;'',''' 􀀧􀀺􀀢􀁾􀀧􀀺􀀧􀀻􀀠I ,,;"-,h':': .' " '.:" 􀀺􀁾􀀬. . , 􀁾􀀠 􀀮􀀺􀀺􀀬􀁾􀁤􀁾􀁦􀁬􀀺􀁾􀁾􀂷􀀠􀀻􀁾􀁬􀁴􀁌� �􀁾􀀺􀁩􀁾􀁾􀁾􀁾􀀺􀁭􀁾􀁾􀀺􀂷􀁳􀀧􀁬􀁾􀀺􀀧􀁾􀀺􀁭􀀻􀁾􀁾􀀻􀁴􀀻􀁾􀁩􀁾􀁦􀁵􀁾􀁾􀁾􀀭􀀺􀀠 􀀻􀀧􀁾􀀻􀀯􀁾􀀧􀁦􀁾􀀠.􀂷􀁾􀀻􀂷􀀡􀂷􀀺􀁾􀀬􀁾􀀺􀂷􀀺􀀬􀀨􀀻􀀮􀁲􀀧􀀠􀀮􀂷􀂷􀁾􀁾􀁦􀂷􀀺􀀻􀁾􀁾􀀾􀁾􀀺􀀬􀁩􀂷􀀺􀀯􀁾􀁾􀁾􀀺􀁾􀁾􀁾􀁾􀀻􀀻 􀀺􀁾􀀡􀁩􀀺􀁾􀀺􀁾􀁾􀀧􀁾􀀬􀀬􀁾􀁊􀀺􀁾􀁾􀁾􀀻􀀻􀁛􀀠.;...'.. .' .'.: ':. -:': 􀀻􀀧􀁾􀁨􀁥􀀺􀁹􀁩􀀬􀀠 :: 􀀭􀀢􀀬􀀺􀁾􀀠 􀀻􀀻􀀡􀁆􀀱􀁾􀀠 􀀮􀂷􀂷􀁴􀀧􀀺􀀺􀀺􀀻􀀺􀁔􀁾􀁥􀀬􀁥􀁮􀁴􀁲􀁹􀀧􀁴􀁯􀂷􀀧􀀺􀁲􀁯􀁵􀁮􀁤􀁡􀁢􀁯􀁵􀁴􀀠oft en:f1aresout.from· :,:·".,:;;:·':),Jaround 􀁡􀀺􀁦􀀱􀁾􀁳􀁨􀀧or' slighcly:raise'd'ceniralisland of up ." "! 􀁾􀀮􀀭􀀮􀀺􀀠Conveiltion'al 'roundabout -.A 􀁯􀁮􀁥􀁾􀁷􀁡􀁹􀀮 circulai":\\',,,",:i;,\derits is'iitributedtoslower·speeds.ind reduced'num:: .. 􀀧􀀺􀀾􀁾􀁾􀁤􀁾􀁡􀁛 􀁾􀁾􀁩􀁩􀁾􀁤􀀺􀁾􀀠􀀲􀁾􀁾􀁢􀀻􀁤􀁮􀁣􀁥􀁮􀁾􀁾􀀻􀁊􀀠island,􀁦􀁯􀁩􀀧􀁾􀁾􀁲􀁾􀁾􀀬􀁬􀁡􀀮􀁴􀀷􀀺􀁾􀀻􀁜􀁦􀀺􀁓􀀮􀀢􀀺􀀼􀁾􀁢􀁾􀁾􀁾􀁾􀁾 􀁣􀀬􀀻􀀻􀁲􀁩􀁐􀁩􀁾􀁴􀁰􀁯􀁩􀁮􀁴􀁓􀀻􀀬􀀻􀀨􀀺􀀻􀁦􀀡􀀻􀁪􀁧􀀺􀀧􀁲􀁥􀀮􀀿􀁴􀀡􀀧􀀺􀀧􀀠::•. '.; .. PUBLIC WORKS DEPARTMENT (972) 450·287) 16801 Wes!grove 27 November 2000 City of Colleyville P.O. Box 185 Colleyville, TX 76034 AITENTION: CURTIS HAWK SUBJECT: INFORMATION RE ADDISON ROUNDABOUT Dear Curtis: Per direction of Chris Terry, Assistant City Manager, Town of Addison, the following documents are attached for your information: Roundabouts -A Design Guide Addison Urban Center Modern Roundabout for Addison Circle wlDrawings Memo to John Baumgartner from Gary Jost re Addison Roundabout Letter from John Baumgartner to Gary Jost re Sensitivity Analysis Traffic Info from Engineering Div. -City of San Buenaventura If you need further assistance, please do not hesitate to call. :4LCo /1/,,!Michael E. Murphy, P.E. Director of Public Works cc: Chris Terry, Assistant City Manager Attachments (As noted above) ,Michael Murphy From: Chris Terry Sent: Thursday, November 09, 2000 1 :34 PM To: Michael Murphy Subject: RE: ADDISON CIRCLE TRAFFIC ENGINEERING INFO. REQUEST No thank you. -----Original Message-From: Michael Murphy Sent: Tuesday, November 07, 2000 11:35 AM To: Chris Terry Cc: carmen Moran Subject: RE: ADDISON ORCLE TRAFFIC ENGINEERING INFO. REQUEST I'll be glad to fOlward study infonnation to him. Do you want to see any of the stuff i plan on sending him? Mike Mi.ekllel 6. Murpk!::J' 1".6. Plreetor of puhli.e 􀁗􀁄􀁲􀁾􀀠 TOw!'\. of Addl5o'" !5;r=<) 450-::21',78' ----Qriginal MessageFrom: ChriS Terry Sent: Tuesday, November 07, 2000 9:30 AM To: Michael Murphy; carmen Moran Subject: ADDISON ORCI£ TRAFFIC ENGINEERING INFO. REQUEST I received a request for infonnation from Curtis Hawk (fonner Southlake city manager and my fanner boss) who is working as a consultant for the City of Colleyville. CurtiS is interested in acquiring any early research or traffic studies we did on roundabouts. Evidently Colleyville wants to introduce roundabouts into their street system. Could one or both of you visit with Curlis on this issue and then provide him with the materials he has requested. 1Cw:lisiGamlleireaGl.....􀀡􀁬􀀡􀁥􀀡􀀡􀁴􀀧􀀪􀀧􀁋􀁕􀁾􀁈= 􀁬􀁉􀁡􀁭􀁬􀁩􀁥􀁦􀁬􀁪􀀮􀁾􀀠fff715'tI-tS/5 of8111511-/581 ., 􀁾􀀠 Thanks. _-----.... -... 􀁾􀀮􀀺􀀠 􀀮􀀧􀁜􀁾􀀭I TOWN OF ADDIsoN PuBLIC WORKS To: GCL-rU ,,-Ye:; .t-From: John Baumgartner, P.E. .j}., J 1\ -'. Director Company: UOl:t')o· ,Y'='cbrn1.1..(j Phone: 214/450-2886 FAX: 214/931-6643 FAX #: 4 q0 -9:1/0 i 16801 Westgrove Date: /􀁾􀀠I j4 I 9S P.O. Box 144 I ' Addison, TX 75001 # of pages (including cover): /;L, DOriginal in mail DPer your request DFYI DCal! me . Comments: PUBLIC WORKS DEPARTMENT (214) 450-2871 1600 1 Wcstgr""ve December 14,1995 Mr. Gary Jost Barton-Aschman, Inc. 5485 Belt Line Rd. Suite 199 Dallas, TX 75240 Re: Addison Circle Dear Gary: Attached is the sensitivity analysis provided by Columbus' design proressionals. Please review and comment at your earliest convenience., Thanks, er, P.E. Director ofPublic Works Thomas P. Smith is the associate director of research for APA. This report was supported by a grant from the National Endowment for the Arts in Washington, D.C., a federal agency. Numerous photos and iIlustrations were submitted by organizations, public agencies, and businesses for use in this report. Special thanks go to Marie E. Witmer, Director of Technical Services for the Institutional and Municipal Parking Congress; Robert Weant, Director of the ENO Foundation for Transportation; Kevin M. Hagerty, Assistant Director of the San Francisco Parking Authority; and Susan Slesinger, Parking Coordinator, Pasadena, California. Cover design by Dennis McClendon Planning Advisory Service is a subscription research service of the American Planning Association. Eight reports are produced each year. Subscribers also receive the PAS Memo each month and have use of the Inquiry Answering Service. Israel Stollman, Exea.ltive Director; Frank S. So, Deputy Exerutive Director; Sylvia Lewis, Publications Director; Welford Sanders, Associate Director of Research; Thomas P. Smith, Associate Director of Research. Planning Advisory Service Reports are produced at APA. James Hecimovich, Editor; Adele Rothblatt, Assistant Editor. © Copyright November 1988 by the American Planning Association, 1313 E. 60th St., Chicago, IL 60637. APA has headquarters offices at 1776 Massachusetts Ave., N.W., Washington, DC 20036. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 The Aesthetics of Parking: An Illustrated Guide By Thomas P. Smith TABLE OF CONTENTS Chapter 1. Better Standards for Parking Design .................................................................. 1 Chapter 2. The Aesthetic Problems With Surface Parking Lots ............................................... 5 The ·Amount of Landscaping ............................................................ .............................. 6 Buffering and Screening ................................................................................................ 6 Performance Screens or Buffers .................................. " .................................................. 7 Sliding-Scale Requirements for Interior Landscaping ......................................................... . 10 Shading Interior Areas of Parking Lots ............................................................................ 10 Point Systems for Overall Landscaping ..................................... ...................................... 11 Regional Differences in Landscaping Codes ...................................................................... 12 Protection of Landscaping ........................................................................................... 12 Maintenance of Landscaping ............................................................................. ........... 13 Chapter 3. Site Planning for Parking Lots ........................................................................ 15 Parking Lot Layout ............................................... ..................................................... 15 Interior Design and Circulation ..................................................................................... 16 Parking Lot Lighting ................................................................................................... 17 Parking Area Signage .............................................................. ................................... 19 Aesthetics of Parking Entrances ..................................................................................... 20 Angle Parking ......................... .................................................................................. 20 Other Site Plan Considerations ............ ", .................................................................. .... 21 Chapter 4. Parking Structures and Urban Design ............................................................... 23 The Boom in Garage Construction ............................................. .................................... 24 Prohibitions on Parking Garages ................................................................................... 24 Mandates or Incentives for Parking Garages ..................................................................... 24 Design Standards for Parking Garages ..................................................................... ....... 26 Chapter 5. Recommendations Based on Current Innovations ................................................ 33 Appendix. A Sample of of Landscaping Standards for Parking Lots and Garages ............................ 37 1. Fairfax County, Virginia, Landscaping Guidelines for Parking Lots and Garages ...................... 37 2. Orlando, Florida, Parking Lot Landscaping Requirements .................................................. 39 3. Landscaping Standards for Nonconforming Parking. Lots, Raleigh, North Carolina ................... 42 Chapter 1. Better Standards for Parking Design Planning commissions across the country have been involved in the design of parking areas for more than 50 years, Columbus, Ohio, is generally considered the first municipality to have adopted parking requirements as part of its zoning code. In August 1923, the city adopted a zoning amendment requiring parking for multifamily dwellings. About 15 years later, the American Society of Planning Officials (ASPO) newsletter began reporting regularly about municipalities adopting parking requirements as part of their zoning codes, ASPO reported that Riverside, Illinois, adopted parking requirements for theaters in 1937, and, in 1938, the ASPO newsletter reported on parking requirements for department stores in Los Angeles and for residential buildings in Bronxville, New York. Surveys by the ENO Foundation for Transportation showed that the greatest number of zoning code amendments for parking came in the post-World War II period1 A March 1947 survey disclosed that only 71 of the 1,060U.S. municipalities with a population of 10,000 Or more had parking requirements in their zoning codes, but a January 1951 recanvass of the same cities found that the number had grown to 203 and that many more cities were working on codes. The objective of these early codes was simply to increase the supply of parking. Many cities at that time were trying to deal with the problems of existing business and residential areas that were built without any parking. 1. Edward G. Morgen and Wilbur S. Smith, ZOrling and Traffic (Westport, Conn.: 􀁅􀁾􀁏 Foundation for Transportation, 1952), 41. A consortium of 19 nearby business otoners in Boston's Post Office Square QreQ recently purchased and began demolition of this 900-car garage. By 1991, the group plans to transform the old, dilapidated garage into a seven-Ieuel, 1.400-car underground facility covered by a 1. 7-Qcre, richly landscaped public park. The city condemned the properly, transferred it to the business group, and sponsored Q design competition for the park. (The Boston Globe) Times have certainly changed. Parking lots and parking garages are now numerous and large, but there is still more need for parking, And the need for parking has extended well beyond the business district and multifamily complex, Parking areas have expanded because of changes in the way people live, work, and learn. Universities, for example, have greatly enlarged their parking areas because of new evening programs for commuters and an increase in the number of students with cars; hospital parking has grown because of a new emphasis on short-term out-patient care; and parking for theaters and entertainment activities has expanded because people have more free time and place a greater value on recreation. Planners who write parking ordinances and create the standards to regulate parking lots and structures are 􀁯􀁦􀁾􀁥􀁮􀀠 asked to balance the need for parking with olhercommunity goals-a more compact urban form, improved pedestrian systems, and enhanced urban design, for example. Virtually all communities want businesses to provide on-site parking in order to prevent congestion on public streets and spillover of traffic to surrounding neighborhoods. Most communities 􀁢􀁥􀁬􀁩􀁥􀁶􀁾􀀠that providing for off-street parking maintains and even increases property values. But these communities have come to realize that the goal of providing adequate parking also conflicts with some economic development, urban design, and environmental goals. Planners understand that large parking lots reduce the land available for development and contribute to drainage and flooding problems. In some major cities, they report that the increased availability of parking encourages people to abandon mass transit for the use of their cars, which, in turn, means making serious air pollution problems worse, And some planners question whether parking is not often overbuilt-stadium parking that is only used a dozen times a year; shopping mall parking built to handle the number of cars that will use the mall on the weekends between Thanksgiving and Christmas; and special event parking for fairgrounds, concert halls, and festival areas that might be used only once a year, The prevalence of parking lots and structures has led to 1 another serious problem that, until recently, did not receive much attention. A major complaint about parking areas is their appearance. Visually, parking lots and parking structures can be a mess. They are often too big, contain too much asphalt or concrete, and have little or no relationship to the buildings and activities around them. They are not inviting places for pedestrians, and they do not have the interest or attraction of other urban open spaces. The size and scale of parking lots and parking garages causes them to break up the links between buildings and destroy the continuity of some streetfronts. Architecturally, many parking areas are just alterthoughts and accessories to urban life. To the public they are a "necessary evil" and often considered "eyesores" and "wasted or dead spaces." Large surlace parking lots in downtown and suburban centers can give these areas the appearance of being only half developed. The long-term solution to improving the aesthetics of parking may be tougher controls controls on the overall amount of parking constructed. These types of controls can be especially significant in districts where large parking areas conAict with important urban design objectives. Boston and Portland have absolute caps on the amount of parking constrocted in their downtowns. Portland'scap is 40,855 parking spaces for its downtown; it currently has almost 38,000 spaces. Boston's cap of 35,500 spaces has already been reached. In certain parts of downtown San Francisco, no surface parking is allowed, and parking structures may not exceed seven percent of the main building's floor area. Portland, Toronto, Seattle, and Bellevue, Washington, have also used zoning to limit the maximum amount of parking that businesses may construct, These controls prevent overbuilding of parking and help reduce the amount 01 land devoted to parking. Given that the demand for parking is likely to continue into the foreseeable future, strictly controlling the amount of parking constructed is infeasible. Instead, it will be necessary to draft policies, plans, and ordinances that work at solving the aesthetic problems with parking lots and structures. This report, based on a survey of over 300 local codes, pulls together information about design improvements and innovations for parking lots and parking structures. The In Chicago, much of Crt-mt Park and the city's famous lake/ront was originally u.sed for parking, In 1954, 􀁴􀁾􀁥􀀠city 􀁾􀁥􀁭􀁯􀀿􀁥􀁤􀀠the, surface parking in what is now northern Grant Park and constructed a 2,lOO-car underground garage. (ChIcago HIstorIcal 􀁓􀁯􀁣􀁵􀁾􀁴􀁹􀀩􀀠 2 It was not until the mid-1970s that Chicago removed surface parking along Monroe Street on the Iakefront. Now the underground Monroe Street garage (over 3, 700 spaces) is topped by a skating rink and garden, (Chicago HistoricalSocietyJ local planners who administer these codes report that they fects of parking lots and structures. It also reports on how have been effective. Their successes and improvements can parking facilities can be designed so that they improve the help provide ideas for other communities. relationship between these structures and surrounding This report offers examples of local design standards that buildings and activities, preventing them from disrupting or work to reduce the ugliness and deadening effects of parkdegrading the quality of commercial areas. Numerous ing facilities, including requirements for landscaping and photographs are used to illustrate these standards and to design improvements that can soften the harshest visual ef-provide examples of well-designed parking facilities. 3 -",-.' 􀀮􀀮􀀬􀀺􀀮􀁾􀀮􀀠.., ., . 􀀧􀀮􀁾􀀠 .0 __􀀭􀀺􀀾􀀮􀁾􀀧􀀠 .--.,'0 -.\ 􀁾􀁯____ 􀁾􀀠 􀀮􀀬􀁾􀀭􀀭􀀺􀀺􀀺􀁟•• 􀁾􀀭􀀬... ...-: . . • _: : J 􀀮􀁾􀀮􀁾􀀮􀀠 • ,. '.0'" ' ..􀁾􀀠 '. ...• .",0' ." -.. _ .... ,,,.:.. ' .....-. '0 ••• ,< " .'. 􀁾􀀭􀀭 -".'. 􀀮􀁾􀀻􀀠 .", . J .:_ ',,'" ...:."...􀀾􀀮􀁾􀀠 '''.:' . f ! Chapter 2. The Aesthetic Problems With Surface Parking Lots For retail business owners, parking is essential to success in the marketplace. In order to compete, many developers of commercial buildings may devote up to two or three times as much space for parking, usually in surface lots,2 as there is floor space in the building being served by the parking. Surface parking lots for regional shopping malls can take up more than 50 or 60 acres. Parking lots for major stadiums and busy airports can take up hundreds of acres. And these lots can dominate urban landscapes. Infact, asa recent parking study indicated, between 80 to 90 percent of all parking demand in the U.S. is satisfied by surface parking lots.' All too often, however, planners give no attention to improving the appearance of parking lots. They overlook the possible effectiveness of parking lot landscaping as a way of maintaining community appearance and property values. In some cases, landscaping4 is considered too pedestrian a concern for site planners and architects. In many cases, land2. Surface parking lots are broadly defined to include any open area, other than a street, used for parking vehicles. The definition covers parking spaces, loading spaces, maneuvering aisles, and other areas used for access to parking and loading spaces. Typically, zoning codes exempt small parking areas (those up to six spaces) from the definition of parking lots and therefore make them exempt from requirements for screening and landscaping. 3. Gerald R. Stocks, "Surface Lot Design," in The Dimensions 0/Parking(2d ed.) by the Urban Land Institute and the National Parking Association (Washington, D.C.: Urban Land Institute, 1983), 51. 4. Local zoning codes define landscaping to include grass, ground cover, shrubs, vines, hedges, trees, fountains, pools, sculpture, benches, benns, fences, patios, walkways, and artwork. Some also allow the preservation of existing trees and vegetation to be applied. to the requirements for landscaping. Most cities do not allow artificial or plastic plant-like materials to qualify as landscaping. Providing a single tree to landscape the acres of parking in this suburban shopping mall is ridiculous. It does nothing to break up the bleak landscape or reduce the monotony of rows and rows of parking. (Thomas P. Smith. Unless noted othenvise, all photos by Thomas P. Smith) scaping is deleted from development plans because of unexpected construction costs or unanticipated space requirements for parking. Because of this, parking lot landscaping often looks like, and is, an afterthought. Landscaping improvements end up being awkwardly spread out over the building site. Sam Hall Kaplan, architecture critic for the Los Angeles Times, says that this lack of planning results in "architectural schizophrenia" because well-detailed, welcoming buildings often stand in striking contrast to their parking. Kaplan complains that the schizophrenia deepens as a person steps through the maze of gritty vehicles, and the dark, oilstained, and seemingly dangerous lot, finally arriving at a sparkling, marble-encrusted lobby. To make the appearance of parking areas more consistent with the buildings they serve, many cities have adopted parking lot landscaping codes. But, frankly, many of these codes just do not work. Typically, they require a few feet of sod along the lot's perimeter and little or no greenery inside the lot. In most cases, the codes lack any appreciation of the potential function of landscaping or the effectiveness of landscaping as a screen or buffer. A good zoning code for surface parking lots focuses on all the details of appearance, including setbacks, buffers, berms, trees, fencing, landscaping, lighting, signage, and paving materials. Chapter 3 explains how local planning commissions, through site plan or speciaJ reviews, have improved the appearance of surface parking lots. It explains how they have related site improvements to the size of the lot, the zoning district in which it is located, nearby land uses, and even cost. The following discussion uSes some general landscaping principles that can be applied when drafting requirements for surface parking lots. Most of these guidelines are applicable to large lots serving shopping centers, offices, and industry. These recommendations may not be applicable to very small parking lots (say, six spaces or less), which are often exempt from landscaping requirements. In some large cities, this exemption may extend to lots of 20 or fewer spaces. 5 Without proper maintenance and care, trees die and compound the aesthetic problems of parking lots. THE AMOUNT OF LANDSCAPING Generous landscaping is the simplest method of enhancing the appearance of parking lots. Itcan break up the wide expanses of parking areas and improve the appearance of new construction. It can also be used to separate pedestrian and vehicular traffic and to delineate the different functional areas of the lot, such as long-tenn, employee parking and short-term, visitor parking. Using landscaping to define clifferent parking areas typically helps to control traffic and lower traffic speeds, thereby ensuring greater traffic safety and efficiency in the operation of the lot. The use of deciduous and flowering trees in a parking lot's interior can provide shade for the cars and the lot's surface. Dense perimeter landscaping can also muffle the noise of automobiles and reduce the glare of automobile headlights and parking lot lighting. But what is generous landscaping? What is the minimum minimum amount of landscaping needed to screen lots from adjacent residences? How much is needed to enhance the overall appearance of the lot itself? In most cases, the answer requires a judgment that balances concerns about aesthetics, community appearance, and costs. In 1964, when the American Society of Planning Officials published Parking LotAesthetics, research suggested that a minimum of 10 percent of the lot area be used for landscaping. Although this may still be a rule-ol-thumb for planners, there is no genera1 consensus. In some communities, 10 percent would be a significant increase, while in others the required percentage has increased to as much as 17 percent. The gross percentage 01 required landscaping is difficult to calculate in modern zoning codes because these codes distinguish between landscaping for perimeter areas adjacent to other properties, perimeter areas adjacent to public rights-of-way, and interior parking lot landscaping. These areas are regulated separately because the landscaping for each serves a different purpose and each requires a unique design. BUFFERING AND SCREENING Many local planners feel the most important part of parking lot landscaping is screening' the lot from the street or nearby residential properties. Many codes include requirements for specific screening techniques, including benning, evergreen plantings, and densely planted hedges. The codes distinguish between walls and landscape screens and typically include standards for the height, Width, type, and density of plant materials. Some even specify the required opacity of vegetative screens. For example, the Hillsborough County, Florida, zoning code requires parking lots with small setbacks (less than 10 feet) from the street to have six-foot screens consisting of masonry walls, wooden fences, or "a row of evergreen shrubs that will grow to six feet in height and 75 percent opacity within two years of planting." According to many local planners, berms and gr.aded slopes can be excellent screens. Although berms may be expensive to construct, they are easy to maintain and more visually pleasing than fences and walls. Berms are particularly appropriate for parking areas because lowheight berms (three to four feet) effectively screen most automobiles. Small hedges or fences (three feet in height) can also be effective. These screens can be maintained on small landscaped strips (five to 10 feet in Width) and constructed at low cost. In some northern climates. communities require these screens to be nondeciduous shrubs to ensure screening all year round. Where wooden fences and masonry walls are permitted, many communities also require the planting of vines or shrubs. Some zoning codes (e.g., Greenacres; Florida) allow the principal builcling to qualify as the screen to the parking lot. The difference between street frontage landscaping and other perimeter area landscaping is typically the degree of. screening required. It is more common to require screens (e.g., berms, fencing, walls, or hedges) along the street front than along other perimeter areas. The only exception is when the adjacent lot is zoned residential. In that case, both 5. Screening means "to conceal" or "to shield:' and some zoning code definitions specify that this may only be ;)t.1;:ompiished with theuse of walls, benns, opaque fences. or denseJy planted shrubs or vegetation, 6 the street frontage and the side yard abutting residential properties require screening. Where the perimeter areas abut other parking lots or commercial or industrial buildings, most communities simply require a landscaped setback. In addition, trees may be required along a parking lot's street front but not be required along other parts of the lot's perimeter. PERFORMANCE SCREENS OR BUFFERS Although most zoning codes rely on very specific requirementsfor screening and buffering, a growing number of communities allow flexibility in landscape design. Many of these new codes take a performance approach to landscaping and buffering, basing the density of required landscaping on the degree of conflict between land uses. The Annapolis, Maryland, code takes a performance approach to buffers and screens. When parking lots of 15 or fewer spaces abut a residentially zoned area, a minimum 1;;foot buffer is required. When a parking lot contains more than 15 spaces, a 20-foot buffer is required. When parking lots abut business zoning districts, a 10-loot minimum buffer is required. The buffer yards for parking areas adjacent to roads and road rights-of-way are more complex. Generally, the width of the buffer is based on the width of the road right-of-way and the width of the parking lot. Buffers adjacent to roads and road rights-of-way must be increased five feet for every 64 feet of parking area running perpendicular to the buffer. Table 1 indicates the minimum buffer widths. Raleigh, North Carolina, also uses a performance approach. It classifies land uses by their land-use characteristics (size, scale, and environmental impacts) and the amount of activity, turn over, or storage in the parking lot. The classification system distinguishes between residential uses, "lOW-impact" uses, "medium-impact" uses, and "high-TABLE 1. BUFFER REQUIREMENTS FOR PARKING LOTS, ANNAPOLIS, MARYLAND Width of Width of Adjacent Parking lot* Right-oE-Way Required Buffer Width 1-64 ft. 60 It. or less 15 It. More than 60 It. 20 ft. 64-128 ft. 60 60 ft. or less 20ft. More than 60 ft. 25ft. 129-192 It. 60 ft. arless 25ft. More than 60 ft. 30 It. 193-256 ft. 60 ft. or less 30 It. More than 60 ft. 35 It. 257-320 It. 60 It. or less 35ft. More than 60 It. 40 It. 321-384 It. 60 ft. or less 40/t. More than 60 It. 45 ft. 385-448 ft. 60 It, or less 45 It. More than 60 ft. 50ft. 􀁾􀁔􀁨􀁥 width ofa parking lot is measured along a 􀁬􀁩􀁮􀁥􀁾􀁮􀁤􀁪􀁣􀁵􀁬􀁡􀁲 to the right-of-way. impact" uses. For example, high-impact uses are bus, train, and truck terminals; stadiums; and heavy industries that handle or distribute materials used in manufacturing, assembly, or fabrication. Medium-impact uses include shopping areas; lodging; colleges and universities; hospitals; outdoor theaters oramusement activities; and 􀁮􀁯􀁮􀁲􀁥􀁳􀁩􀁤􀁥􀁮􀁾􀀠 tial uses allowed in residential areas. The low-impact uses are offices; cemeteries; fire statioos; schools; and churches, 􀀵􀁹􀁮􀁡􀁧􀁯􀁧􀁵􀁥􀁳􀁾􀀠convents, or monasteries. The Raleigh system establishes "transition yards" for each of these classifications. A transition yard can be a wide setback of turf or a narrow strip with a high density of shrubs and trees. The narrower the yard between the parking lot and its neighbor, the more shrubs and trees required. The possible trade-oils between various widths of turf and various densities of landscaping are specified in the ordinance, and builders may choose from this range of options. For example, when a parking lot for a truck terminal Or stadium abuts a single-family residential area, the code requires either a deep, 200-foot, transition yard (primarily lurf) ora yard as small as 40 feet if it is densely planted. The code is written so that a wide variety in the depths of yards and density of plantings is allowed between these two extremes, Some planners argue that screens and buffers are not the best solution to minimizing the adverse visual impact of parking lots. They argue that, instead of hiding these spaces, communities should look for opportunities to make them This Schaumburg, Illinois, office building includes wide setbacks and art extensively landscaped entranceway_ (Tigerhill Studios, Inc.) Screens come in all shapes and sizes, and many are very effective in shielding automobiles, Most screens are inexpensive, require very little land, and do not need extensive maintenance. A fence (above photo) screens a side yard; the berm (top right) shields all but the top ofthe automobiles; the office building (center) uses a false facade to screen the parked cars; and the remaining photos show other uses of landscaping and walls or screens. 8 -... 􀁾􀀠 9 more attractive and usefu1. These planners suggest more attention to the appearance of the interior of parking lots and interior landscaping. The discussion that follows explains ways of improving the appearance of interior parking areas. SLIDING-SCALE REQUIREMENTS FOR INTERIOR LANDSCAPING Some zoning codes requlre interior landscaping to enhance the appearance of parking lots, especially of large lots that have significant visual impacts. The parking lot landscaping codes of Bellevue and Redmond, Washington; Palo Alto, California; the town of Waterford, Connecticut; and San Buenaventura, California, use sliding-scale standards that require interior landscaping in amounts determined by the size of the parking lot. In some cases, the standards for large parking lots provide incentives to encourage builders to break up the lot into distinct sections. These smaller sections usually have less impact on the environment. In Palo Alto, five percent of the interior of parking Jots smaller than 15,000 square feet must be landscaped. This figure rises to 7.5 percent for lots between 15,000 and 29,999 square feet, and to 10 percent for lots larger than 30,000 square feet. A business's parking lot may be treated as mond, Washington, uses similar but slightly less restrictive standards. Five percent of the interior allots between 6,000 and 30,000 square feet must be landscaped, and seven percent of the interior oHots larger than 30,000 squarefeet must be landscaped. Parking lots smaller than 6,000 square feet do not have to have any interior landscaping. The San Buenaventura zoning code is a little tougher than the Palo Alto, Bellevue, and Redmond codes. It requires that 10 percent of the interior of a lot with 22 or more parking spaces be landscaped; the requirement is five percent for lots with 10 to 21 parking spaces. There is no landscaping requirement for lots with fewer than 10 parking spaces. SHADING INTERIOR AREAS OF PARKING LOTS Many local landscaping codes place a premium on the use of trees (particularly shade trees) to satisfy local parking lot landscaping requirements, In warm weather climates, such as southern California, Florida, some southwestern states, and even in parts of Colorado, trees are considered essential to moderating the heat gained by asphalt parking lots. Anumber of California communities, including Agoura Hills, Sacramento, Woodland, Sacramento County, and Modesto, require that shade trees be placed in such numbers Ptdm trees in the this Hal Harbour, Floriduf shopping center break up the wide expanses of parking and enhance the appearance of the shops and stores. Palm trees, however, do not offer much shade. several separate parking lots if the site design makes each clearly distinct and separate. This separation may be achieved by yards or buildings. The Bellevue, Washington, zoning requirements are similar to those ofPalo Alto, but they are expressed in terms of landscaping per parking stall. For parking lots smaller than 50 spaces, the Bellevue code requires 17.5 square feet of landscaping per parking stall; for lots having between 50 and 99 spaces, it requires between 17.5 and 35 square feet of landscaping per stall, as determined by the planning director; and for parking lots with more than 99 spaces, the code requires 35 square feet of landscaping per stall. Nearby Redand locations so that a certain percentage of the total parking area is shaded within 15 years of the issuance of all development permits. In Sacramento, tree canopies must shade 60 percent of the lot within 15 years, and, in Agoura Hills, 50 percent of the lot must be shaded within 15 years. In Sacramento County, trees in small lots of five to 24 spaces must provide 30 percent shading of the entire lot; in lots of 25 to 49 spaces, they must provide 40 percent shading; and in lots larger than 50 spaces, trees must provide 50 percent shading. In Woodland, shade trees must be distributed so that 40 percent of the parking stalls are shaded at high noon when trees are at full foliage. The Modesto code is less 10 Trees in the parking area of this new office building in Livennore, California, will eventually shade the majority of the 101. (Pacific Aerial Survey) precise; it states only that "a minimum of one deciduous shade tree is required for every 10parking spaces" and tha t "the distribution of the trees must maximize shading during the summer months." Some cities require shade trees based on the number of parking stalls and do not specify that a certain percentage of the lot must be covered by a tree canopy. Typically, however, these codes require trees to be distributed so as to maximize the amount of the lot shaded. A sample of standards follows. "One tree for every 15 parking spaces in parking lots of 15 Or more spaces." The code further requires that the trees be distributed to break up the lot and create a canopy effect. (Col· orado Springs..-Colorado) "On€ tree for every 10 parking spaces and three shrubs for every 10 spaces." (Leesburg, Virginia) One deciduous shade tree and three shrubs forevery 10 park· · iog spaces are required in parking lots that exceed 12,000 square feet or 40 spaces. (Santa Fe, New Mexico) In parking lots for commercial and industrial development, "a minimum of one ls..gallon lree forevery five parking stalls, plus a minimum of 15 percent landscaping for the total site devoted to parking are required. Urvine, CaJifornia). "One shade tree for every 10 parking spaces (is required] in parking lots of over 20 parking spaces." (Redding. California) Trees are required at a rate of "onefor every 2,000 square feet of parking area." (Raleigh, North Carolina) "At least one tree not less than 2.S-inches caliper at a height of three feet [isrequiredj for each 12parking spaces." (Wilton. Connecticut) Parking lots for more than 20 Cars must have at least "one tree of t\.vo--inch caliper or larger for every eight parking spaces." [Town of Yarmouth, Massachusetts) POINT SYSTEMS FOR OVERALL LANDSCAPING Some new zoning codes use point systems that allow a variety 01 designs for screening and interior landscaping of parking lots. Communities as diverse as Madison, Wisconsin; Dallas, Texas; and Orlando, Florida, use such systems. In Madison, the number of points required are determined on the basis 01 the following formula: 50-(1 +n/1,000) In this case, n is equal to the total numberof parking spaces or equal to the total square footage of the lot divided by 300 square feet (the city's average for parking stall size). Once the number of points is calculated, a landscape designer may use trees, shrubs, and other landscape elements to gain the necessary points for code compliance. The following point values are assigned for different types of landscaping. Element Point Value Canopy Tree, 2tf to 2,5'" caliper 75 Deciduous Shrub, Variety of plant sizes recommended 3 Evergrom Shrub, Variety of plant sizes recommended 5 Decorative WaH Or Fence, minimum height three feet (points per 10 lineal feet) 10 Earth Benn, average height 30' (points per 10 lineal feet) 10 Earth Berm, average height 15"' (points per 10 lineal feet) 5 Evergreen Trees, minimum height 36" 30 Canopy Tree or Small Tree (e.g., Crab, Hawthorne, etc.), 1.5" to2'" caliper 30 In addition, the Madison code applies the formula n/12 -(1 + n/l,ooo) to caluclate the number of trees required. As above, n is equal to the total number of parking spaces or to tl)e total square footage of the lot divided by 300 (the city's average stall size). The number of trees required by this formula can not be included in the point count for other landscaping. The Madison code does not specify where the landscaping must be placed, except that, in lots with 50 or more spaces or two or more driving aisles, at least one-half of the trees must be in the lot's interior. The Orlando, Florida, development rode has the most elahorate point system for parking lot landscaping. In Orlando, the easiest way to get the necessary points is to retain or install trees. The code requires trees and other landscaping in order to screen parking from adjoining land uses and to provide shading within parking lots. The minimum requirements are expressed in terms of tree points. (See the excerpt from the Orlando code in the appendix.) For exampie; the perimeter parking lot landscaping standard requires "sufficient canopy trees to receive at least three tree points per 100 lineal feet of frontage." The interior parking lot landscaping standard requires "sufficient canopy trees to receive at least one tree point per100 square feet of landscaped area within the lot." Small native canopy trees are worth between .85 and 1.25 tree points; medtum-size native trees are worth 11 2,5 points; and large orspedmen-size native trees are worth five points. The dasses of trees (small, medium, and large) are defined by their height and the diameter of the tree trunk. According to Orlando planners, the point system strongly discourages the dear-cutting of trees for parking lots and creates a strong incentive for preserving patches of landscaping, Developers are given points for saving a tree and are given added points for protecting large trees or dusters of trees. The Dallas code, adopted in 1986, also establishes a point system for measuring compliance with its parking lot landscaping code. The code applies to all new development except duplexes and single-family homes, and new buildings within the central business district. Developers of parking lots for retail, office industrial, or multifamily projects must submit landscaping plans andmust earn a minimum number of points before the dtywill grant development approval. The numberoi points required varies; for example, the code requires 30 points for parking lots that abut a residential use but only 20 points for a lot that abuts a nonresidential use. Ten points are awarded for any of the following: 1. Screening of lots to a height of at least three feet; 2. Interior landscaping of at least seven percent; 3. The planting of canopy trees at a rate of one per 10 parking spaces; or 4. Buffer strips of at least 20 feet in width along a lot's perimeter. Five points can be awarded when one large evergreen shrub is planted for every 10 feet of perimeterarea orwhen one large, noncanopy tree is planted for every 30 feet of perimeter area. The building official may also grant points for the preservation of existing trees. Up to five P!'ints can be awarded for the use of unique and pJeasingpaving materials. Finally, one point is awarded "for each one percent increment of a lot" that is used for fountains, covered walkways, seating areas, or outdoor recreation areas. REGIONAL DIFFERENCES IN LANDSCAPING CODES Significant regional differences exist in parking lot landscaping codes. In the Midwest and Northeast. a number of communities allow developers to transfer some required interior landscaping to the perimeter of a parking lot. This transfer is permitted typically in high-turnover parking lots because of problems 'with snoW removal. It is usually much easier to dear parking lots of snow when landscape islands do not prevent the operation of snow plows. The most significant regional trend, however, is the enactment of parking lot landscaping codes that require the use of plants and designs that conserve water. These are "xeriscape" codes (derived from the Greek word. xeros, meaning dry). In California, Los Angeles, Contra Costa County, Santa Barbara County, and Ventura County require the use of water-conserving plants. Many of these codes also liiltit the amount of turf used in the landscaping of parking lots (grass requires large amounts of water to be maintained). These water-conserving codes also require the use of irrigation systems that are electronically set for night andlor early morning irrigation and the use ofstormwater collection designs that collect and recycle water. The landscape islands of this Oakbrook, Illinois, shopping center include ample space to protect the root system of trees and curbing that prevents cars from encroaching on the landscaping. The Pima County, Arizona. code is probably the premier example of a code that requireslow-water-use landscaping, The Pima code promotes conservation of the desert environment. The ordinance encourages the use of low-water-use plants and limits the use of water-intensive turf. The,Pima code also allows developers to duster landscaping into a "mini-oasis" where it is much easier to harvest rainwater for irrigation and centralize maintenance of vegetation. Other regional differences appear in the types of trees and shrubs permitted. Most zoning codes encourage the use of native plants and trees. When the types of permitted trees or shrubs are specified in local codes, such lists should be developed in cooperation with local nurserymen, landscape architects, and horticulturists. PROTECTION OF LANDSCAPING To ensure the long-term protection of landscaping, developers must coordinate landscape designs with grading and excavation plans. Such planning is particularly critical when landscaping plans include the retention of existing vegetation. When retaining existing trees in parking areas, enough ungraded ground around the tree should be left to allow for its survival. Standards in Fairfax County, Virginia, state that "grading should not be permitted within the drip line of trees to be retained." The "drip line" isa vertical line from the outer edge of a tree canopy to the ground. The county requires this area to be staked out and protected (e ,g., by fenCing) from heavy equipment traffic or from use for the stockpiling of equipment, dirt, Or construction materials. Grading must not encroach on a tree's root zone in ways that threaten the survival of the tree. According to some 12 landscape horticulturists, even shallow cuts of six to eight inches can remove a tree's or shrub's feeder roots and expose deeper roots to drying and freezing. Deeper cuts may sever a large portion of the root system, depriving trees of water and increasing the chance of wind damage to weakened plants. Finally, even shallow grading in the vicinity of trees removes top soil, natural mulch, and ground vegetation that is important to the health of trees and shrubs. Excavation for new utilities, foundationsT and basements must also be planned so that it does not adversely affect important vegetation. Generally, such excavation should be kept out of the area within the drip line of trees. When utilities are installed, all lines (electrical, phone, and even cable television lines, if possible) should be laid so that additional excavation is not required at a later date. New trees, shrubs, and turf must be installed carefully and protected from damage that can be caused by encroaching carsand trucks. Landscaping needs to be able togrowwithout beingbumped orbanged by parking cars. Raised planters, fences, or curbs and edges can be used to stake out a landscaped area. Typically, landscape architects must also determine whether the root development of new trees will ultimately cause any interference with walls, walks, drives, patios, and other paved surfaces. The same is true when considering possible interference with sewer lines, septic systems, and underground drainage systems. installation plans also require the selection of appropriate planting materials. Local owners of plant nurseries, agricultural extension agents, and landscape architects are good sources of advice or consultation. When choosing trees for parking lots, the primary concerns are longevity, crown size (for shading purposes), aesthetics, and nuisance factors. Trees that drop sap should be avoided, and trees that drop large amounts ofblossams, seeds, and pods that might clog drains may also have to be avoided. Deciduous trees that drop leaves can be be used if parking lots are periodically cleaned. Hearty trees resistant to motorexhaust fumes, dirt, and soot should be used. Trees that are susceptible to insects and disease should be avoided, and trees with expansive roots that could disrupt paving and underground lines should be discouraged. in cold climates, the use of trees that are tolerant of road salt and deicing compounds must be