/
BARTON-ASCHMAN ASSOCIATES, INC. 5485 Belt Lu>e Road. Suite 199· Dallas, Te)(3S 75240 USA. (214) 991·1900. Fax: (214) 490-9261 To: From: Date: Subject: 􀀭􀀧􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀧􀀠DRAFT 􀁾􀁜MEMORA"::)
Ron Whitehead Town of Addison Gary Jost June 9, 1993 Addison Toll Tunnel Analysis This memorandum presents the findings and recommendations of the analysis of various transportation
issues related to the proposed Addison Toll Tunnel. Specifically, the following three issues are addressed: • Impact of Arapaho Road extension on toll tunnel projections. • Impact of
proposed toll tunnel on Addison Airport circulation and access. • Impact on adjacent signalized intersections by toll tunnel traffic. These three key issues are discussed separately
below: Arapaho Road Extension The extension of Arapaho Road from its existing terminus at Addison Road to Marsh Lane has been proposed to alleviate traffic congestion on Belt Line Road
and provide increased mobility for Addison residents. The roadway is included in the Addison Thoroughfare Plan as a four lane divided arterial. The estimated traffic volumes and the
impact of the roadway on projected toll tunnel volumes have been evaluated on two occasions: as part of the development of the Addison Transportation Plan and more recently by Wilbur
Smith Associates (WSA). The first evaluation utilized the regional traffic forecasting models for the area developed by the North Central Texas Council of Governments (NCTCOG). The evaluation
of traffic assignments with and without the extension of Arapaho Road concluded that there was no significant impact on project toll tunnel volumes by the Arapaho Road extension. A copy
of our December 18, 1992 memorandum reporting these results is attached. The second evaluation, conducted by WSA and reported in their May 13, 1993 letter, utilized WSA's model specifically
developed to develop traffic volumes and revenue projections for the Toll Tunnel. This report is attached foJ" your review. The WSA evaluation indicated a fifteen percent (15%) decrease
in vehicles per day assuming full build-out of the Arapaho extension in the year 2010. This also assumes a $.50 toll for the tunnel. 􀀨􀁾􀁬􀁰􀁁􀁒􀁓􀁏􀁎􀀤• TRANSPORTATION CiROUP 
Barton-Aschman has reviewed WSA's report and subsequent limited information provided by WSA and offer the following comments: • The reduction of the toll from $.75 to $.50 results in
a fourteen percent (14%1 decrease in revenues in the year 2010 exclusive of the extension of Arapaho. • The report confirms that the Arapaho Road extension serves primarily to reduce
traffic volumes on Belt Line Road. Although this indirectly affects the toll tunnel projections, the Arapaho Road extension does not directly compete with the tunnel. A significant increase
in Belt Line Road capacity (i.e. grade separations and/or additional lanes) could have a similar effect on toll tunnel volumes. • The originally forecast volumes (at a $.50 toll and
without the Arapaho extension) indicated that 25,500 vehicles per day (vpd) would use the proposed tunnel. Based on peak hour factors and directional splits assumed in the original traffic
and revenue report prepared by WSA, approximately 1 ,800 vehicles would utilize the tunnel in one direction during the AM peak hour. This volume equals the saturation flow rate of a
single arterial lane unaffected by delays at traffic signals. With this volume of traffic, the opportunity for the toll tunnel to offer an advantage in time and operating conditions
could be significantly affected and traffic volumes could decrease until this advantage is once more achieved. An analysis of delays at the intersection on either side of the tunnel
is presented later in this memorandum. Addison Airport The proposed tunnel impacts circulation and access within the Addison Airport. At its eastern terminals, a vehicular access drive
has been proposed immediately adjacent to the tunnel intersection with Addison Road. This proposal would present operational and safety concerns because it would, in effect, create a
fifth approach to the intersection. The proposed driveway location also does not address potential expansion opportunities of the tunnel and would have to be relocated if the tunnel
is expanded. An alternative access and circulation plan for this area of the airport has been prepared and submitted to the Town of Addison for review. Costs for implementing this revised
plan have not been prepared, but should be included in the total tunnel project costs. Properties adjacent to the western terminus of the tunnel will lose access to the signalized intersection
at Keller Springs Road and Midway Road. Other properti he west side of the airport will be provided access only from Dooley Road which ill in be c nverted to a cul-de-sac under the present
proposal. Dooley Road is accessed Mi ay Road at a unsignalized intersection. A revised access plan should be prepared for this area which provides additional access to these properties
and considers future expansion of the Addison Airport. Intersection Analysis The proposed toll tunnel will complete Keller Springs Road between IH 35 and Preston Road and provide an
important regional transportation link for the area. The existing segments of , . 
Keller Springs Road has critical signalized intersections which will be impacted by tunnel traffic. These intersections have been analyzed and findings reported in the attached memorandum
dated May 5, 1993. The analysis identifies the following specific intersection improvements to mitigate the impact of the proposed tunnel: Keller Springs at Midway Widen the north, west,
and south approaches to provide dual left turn lanes. Widen the east approach to include a single left, two throughs, and an exclusive right turn lane. Provide exclusive right turn lanes
on the west and south approaches. Keller Springs at Addison Road Widen the west approach to provide a single left, two throughs, and an exclusive right turn lane. Widen the east, south,
and north approaches to provide dual left turn lanes. Keller Springs at the Dallas North Tollway Additional analysis is currently underway at this intersection. Without the traffic that
is projected to use the tunnel, these intersections, excluding the Keller 1 SpringsIDNT intersection during the PM peak hour would operate at acceptable levels of service. Without the
recommended improvements described above, all intersections will operate at unacceptable levels of service when toll tunnel traffic is included. Vehicular delays at these intersections
could equal or exceed delays currently being experienced at major intersections along Belt Line Road if intersection improvements are not implemented. The cost of these improvements
should be included in the total toll project costs. Recommendations Based upon the findings of this study, we would offer the following conclusions and recommendations: The extension
of Arapaho Road will serve it intended purpose of providing improved mobility to Addison residents by offering additional east/west capacity for local travel. We therefore recommend
that the Arapaho Road extension remain on the Addison Thoroughfare plan and Right-of-Way be reserved for its construction. The proposed toll tunnel impacts circulation and access to
the Addison Airport. Additional planning should be undertaken to develop a comprehensive circulation and access plan for the airport considering both the existing conditions and future
expansion plans for the airport and the costs of implementation included in the toll project costs. 
, The proposed intersection improvements are directly attributable to the traffic using the proposed toll tunnel. The"se improvements should be implemented prior to the opening of the
tunnel and included in the toll project costs. The proposed toll tunnel offers an excellent opportunity for improving regional mobility in the area but will not, by itself, relieve traffic
congestion on Belt Line Road. Gary\whitehe3.mem 
WILBUR SMITH ASSOCIATES ENGINEERS. ECONOMISTS. PlANNERS 135 COLLEGE STREET. P.O. BOX9412 • NEW HAVEN. CT 06534. (203) 865·2191 • FAX (203) 624·0484 May 27, 1993 . Mr. Robert Wunderlich
Principal Associate Barton-Aschman Associates, Inc. 5485 Beltline Road Suite 199 Dallas, Texas 75240 Dear Mr. Wunderlich: I received your letter of May 19, 1993 concerning the additional
information you requested on the Arapaho Road Extension project as it re1ates to the Addison Toll Tunnel. You indicated in that letter that you required some additional information in
order to complete your evaluation ofthe informatIon provided. Enclosed for your use is a listing of the network attributes for the focus area involved in the assignment process. It should
be self-explanatory and useful for your continued evaluation. The item concerning the percentage of traffic that' would use the Dallas North Tollway and the proposed Toll Tunnel from
our ,original projections indicated that approximately 6.8 percent of all the trips using. the. the. project would make use of the Dallas North Tollway to access the Downtown Dallas
region. This is unchanged from the final feasibility report provided to the Texas Turnpike Authority. Finally, the information that you requested for the travel time and cost algorithms
used in the assignment process cannot be provided to you. You can certainly' appreciate that this information is proprietary to Wilbur Smith Associates and is not available for transmission
to Barton-Aschman for your use. In any case we have now provided all the information that we believe can reasonably be expected on this project and trust that it meets your requirements.
If you have any questions regarding the information provided, please do not hesitate to call. Sincerely, SImla cc: Gary D. Jost -Barton-Aschman I John Baumgertner -Town of Addison ALBANY.
NV • ATlANTA.GA • CAIRO. EGYPT. CHARLESTON. SC • COLUMBIA. SC • COLUMBUS. OH • DES MOINES. IA. FALLS CHURCH. VA HONG KONG. HCUSTON. TX • KNOXVILLE. TN • LEXINGTON. KV • LONDON. ENGLAND
• LOS ANGELES. CA • MIAMI. FL • NEENAH. WI NEW HAVEN. CT • OAKLAND. CA • ORLANDO. FL • pmSBURGH. PA • PORTSMOUTH. NH • PROVIDENCE. RI • RALEIGH. NC • RICHMOND. VA RIVERSIDE. CA • ROSELLE.
IL • SAN FRANCISCO. CA. SAN JOSE. CA • SINGAPCRE • TAMPA. FL • TORONTO. CANADA. WASHINGTON. DC EMPLOVEE·OWtolED COMPAtoIy 
Town of Addison KELLER SPRINGS TOLL TUNNEL POSITION PAPER The Town of Addison feels strongly that both the proposed Keller Springs Toll Tunnel project and the extension of Arapaho Road
within the Town limits are needed to help meet transportation needs of the region and the Town. The Town has long recognized the importance of an effective transportation system to its
success and continued growth. The Town has worked with neighboring cities, Dallas County, the Texas Department of Transportation (TxDOT), the North Central Texas Council of Governments
(NCTCOG), and the Texas Turnpike Authority ITTAl to encourage and assist in the planning and implementation of a transportation system that meets both the needs of the Town and region.
The Keller Springs Tunnel has long been recognized as a logical transportation link that would significantly increase east-westroadway capacity in the highly congested North Dallas County
Corridor. The Tunnel would link two existing segments of Keller Springs Road creating a major regional arterial that would increase accessibility to the Dallas North Tollway (DNT). Recently,
the Tunnel has been proposed as a tollroad project by the TTA. The Keller Springs Toll Tunnel offers an excellent opportunity for improving regional mobility in the area but will not,
by itself, relieve traffic congestion currently being experienced within the Town of Addison. The improvement of local mobility and accessibility is an equally high priority for the
Town. The extension of Arapaho Road, from its existing terminus at Addison Road, to Marsh Lane has been planned to alleviate traffic congestion on Belt Line Road and provide increased
local accessibility to serve the needs of both businesses and citizens of the Town. The Town began acquiring right-of-way for the Arapaho Road extension in 1987 and more recently has
prepared schematic design plans for the extension. The roadway is included in the Town of Addison Thoroughfare Plan as a four-lane divided arterial. The Town Council is unanimously committed
to to the construction of Arapaho Road. The Town of Addison heartily supports the continued study, planning, and implementation of these two important projects for the area. The recent
study conducted by Wilbur Smith and Associates {WSAI for the Town confirmed the Town's belief that the two facilities do not directly compete. Arapaho Road serves to reduce traffic volumes
and congestion on Belt Line Road rather than providing a desirable alternative to the Keller Springs Tunnel. Although the WSA report identifies a marginal impact on Toll Tunnel volumes
with the Arapaho Road extension in place, the Town maintains its position that the construction of the Arapaho Road extension will have no appreciable impact of the projected Toll Tunnel
volumes for the following reasons: Travel forecasts developed by the NCTCOG, as part of the Town of Addison Transportation Plan Development Study, projected no decrease in traffic volume
using the Keller Springs Tunnel resulting from the extension of Arapaho Road. East/west travel demand in the corridor continues to increase as evidenced by the increasing levels of congestion
in the area. Traffic volumes on Belt Line Road are increasing at an annual rate of three percent (3%). "Any increased 1 
capacity in the corridor will be effectively utilized. Projected year 2010 volumes (at a $0.75 toll) on Arapaho Road between Addison Road and Midway Road are in excess of 32,000 vehicles
per day (VPD). This equates to a volume to capacity ratio of (vIc) of 1.30. This vIc ratio indicates a high level of congestion on this roadway segment. Drivers typically divert to alternate
routes when levels of congestion reach this level. Both Belt Line Road and the Keller Springs Toll Tunnel are projected to have lower vIc ratios. Arapaho Road will serve local traffic
while the Keller Springs Toll Tunnel will serve to improve accessibility to the Dallas North Tollway for vehicle trips originating or having destinations in the Keller Springs corridor
west of Addison Airport. The extension of Arapaho Road and the Keller Springs Toll Tunnel are two important elements of a transportation system for the North Dallas County Area. Properly
planned and implemented, these projects will provide improved mobility to local and regional traffic in the area. The Town of Addison also maintains that, in order to maximize the success
of the proposed Keller Springs Toll Tunnel, the project should be planned and developed as part of a system rather than a singular roadway segment. The ability of the Tunnel to attract
traffic will be dependent on its ability to offer motorists reduced travel time. This advantage can only be achieved through an efficient transportation system serving the Toll Tunnel.
The failure of any segment of the system will decrease the ability of the Tunnel to provide a travel time advantage. Therefore, the Town proposes that the following items be included
in future planning and analysis of the Keller Springs Toll Tunnel project: Impact on Keller Springs Road -Keller Springs Road will be the primary roadway serving the Tunnel. There are
several critical intersections along Keller Springs Road that will be impacted by the additional traffic using the Tunnel. These intersections include Keller Springs and the Dallas North
North Tollway, Keller Springs and Addison Road, Keller Springs and Midway Road and Keller Springs and Marsh. The intersections of Keller Springs with the Dallas North Tollway, Midway,
and Marsh currently experience extremely high volumes during the peak hours. The Town has conducted an evaluation of the intersections within its Town limits and has concluded that significant
roadway improvements will be necessary to provide an acceptable level of service at these critical intersections. The ability of Keller Springs to provide access to adjacent properties
while providing acceptable levels of service should also be evaluated. Keller Springs Road is currently a four-lane divided facility both east and west of the proposed Tunnel. Adjacent
property along these segments is mostly undeveloped. The ability to meet both local access needs, which require a higher level of access, and regional transportation needs, which desire
limited access to adjacent properties, must be carefully studied to insure that both needs are met. 2 
Impact on Addison Airport -The proposed Tunnel impacts the operations of Addison Airport including vehicular and aircraft circulation, and access to adjacent businesses. The Airport
provides a major economic benefit to the Town and maintaining its economic viability is of the utmost importance. The engineering report prepared as part of the Keller Springs Toll Tunnel
Feasibility Analysis included four million dollars for Right-of-Way acquisition. The Town feels that this amount is not adequate to properly address the impacts of the Toll Tunnel on
the Airport and proposes that additional study be conducted to identify the total cost of recommendations to mitigate all impacts to the Addison Airport. Impact of Toll Booths on Intersection
Operations -The proposed location ofthe Tunnel toll booths is approximately 150 feet east of the intersection of Keller Springs Road and Midway Road. This location has raised concerns
that traffic waiting to enter the Tunnel will queue up into the intersection creating an unsafe condition. No analysiS to date has been presented to alleviate these concerns. Further
study should be undertaken to ensure that queues created at the toll booths do not create unsafe conditions at adjacent intersections. Impact on Dallas North Tollway -The proposed Tunnel
will provide a direct link to the Dallas North Tollway via Keller Springs Road. This will provide increased volumes for the DNT directly resulting from the Toll Tunnel. Because of this
direct benefit, the Town of Addison feels that the proposed Tunnel should be included as part of the DNT system rather than be a separate project. This inclusion into the DNT system
would insure the financial success for the Tunnel. As stated earlier, the proposed Tunnel will impact the intersection of Keller Springs Road and the Dallas North Tollway. The ability
of this intersection to operate at an acceptable level of service will be important to the desirability of the Toll Tunnel route. The additional analysis to identify improvements to
this intersection should include alternatives that would provide a direct link between the Toll Tunnel and the DNT. The inclusion of an analysis to identify the improvements that will
create a safe and effective transportation system to serve the proposed Toll Tunnel will certainly identify additional costs that should be included in the financial feasibility analysis
of the project. In summary, the Town of Addison supports the Keller Springs Toll Tunnel as well as the extension of Arapaho Road. Both projects are necessary to provide a safe and effective
transportation system to meet the needs of the Town and the region. The Town is committed to the extension of Arapaho Road and feels strongly that this extension will have no significant
impact to Toll Tunnel projections. The Town advocates the additional analysis of the Toll Tunnel project to ensure that the proper transportation system is in place to support the Toll
Tunnel, that adequate improvements are implemented at the Addison Airport to ensure its continued economic success, and that the Toll Tunnel is a cost·effective expenditure of funds.
The Town further supports the inclusion of the Keller Springs Toll Tunnel Project into the Dallas North Tollway Project. 3 
WILBUR SMITH ASSOCIATES ENGINEERS. ECONOMISTS. PLANNERS 135 COLLEGE STREET. P.O. BOX 9412 • NEW HAVEN. CT 06534 • (203) 865-2191 • FAX (203) 624-0484 May 27, 1993 Mr_ Robert Wunderlich
Principal Associate Barton-Aschman Associates, Inc_ 5485 Beltline Road Suite 199 Dallas, Texas 75240 Dear Mr-Wunderlich: I received your letter of May 19, 1993 concerning the additional
information you requested on the Arapaho Road Extension project as it re1ates to the Addison Toll Tunnel. You indicated in that letter that you required some additional information in
order to complete your evaluation of the information provided_ Enclosed for your use is a listing of the network attributes for the focus area involved in the assignment process_ It
should be self-explanatory and useful for your continued evaluation. The item concerning the percentage of traffic that would use the Dallas North Tollway and the proposed Toll Tunnel
from our original projections indicated that approximately 6.8 percent of all the trips using the project would make use of the Dallas North Tollway to access the Downtown Dallas region.
This is unchanged from the final feasibility report provided to the Texas Turnpike Authority. Finally, the information that you requested for the travel time and cost algorithms used
in the assignment process cannot be provided to you. You can certainly' appreciate that this information is proprietary to Wilbur Smith Associates and is not available for transmission
to Barton-Aschman for your use. In any case we have now provided all 􀁾􀁨􀁥􀀠information that we believe can reasonably be expected on this project and trust that it meets your requirements.
IT you have any questions regarding the information provided, please do not hesitate to call. Sincerely, s Simla Gary D. Jost -Barton-Aschman J John Baumgertner -Town of Addison ALBANY.
NY • ATLANTA. GA • CAIRO. EGYPT. CHARLESTON. SC • COLUMBIA. SC • COLUMBUS. OH • DES MOINES. IA • FALLS CHURCH. VA HONG KONG. HOUSTON. TX • KNOXVILLE. TN • LEXINGTON. KY • LONDON. ENGLAND
• LOS LOS ANGELES. CA • MIAMI. Fl • NEENAH. WI NEW HAVEN. CT • OAKLAND. CA • ORLANDO. FL • PITTSBURGH. PA • PORTSMOUTH. NH • PROVIDENCE. RI • RALEIGH. NC • RICHMOND. VA RIVERSIDE. CA
• ROSELLE. IL • SAN FRANCISCO. CA • SAN JOSE. CA. SINGAPORE. TAMPA. FL • TORONTO. CANADA • WASHINGTON. DC EMPLOYEE-OWNED COMPANY 
BARTON-ASC:HMAN ASSOC:IATES, INC:. 5485 Belt Line Road, SUite 199. 􀁄􀁡􀀡􀁾􀁡􀁳􀀮􀀠Texas 75240 USA. (214) 991-1900· Fax: (214) 490-9261 May 19, 1993 Mr. John Smolley, Jr. Associate Wilbur
Smith Associates 135 College Street New Haven, Ct. 06534 Dear Mr Smolley; We have received your letter dated May 13, 1993 regarding Wilbur Smith's analysis of the impacts that the extension
of Arapaho Road from the Dallas North Tollway to Marsh Lane would have on the proposed Addison Toll Tunnel Project. In order For Barton-Aschman to complete its evaluation and present
a report to the Town of Addison, we require the following information; A listing of Roadway network attributes for all roadways within the focus area including number of lanes, capacity,
and speeds. '., ' The volume plots associated with the traffic'assignments conducted under this contr.act. The percentage of traffic using the Dallas North Tollway that also uses the
proposed toll tunnel. The travel time and cost algorithms used for the traffic assignment process. Please furnish this information by Wednesday, May 26, 1993 so we can finalize our report
to the Town of Addison. In addition, please keep in mind that Wilbur Smith is under contract to Barton-Aschman for this study. All data, reports, analyses and other information collected
or developed as part of this contract are confidential and shall not be made available to third parties unless authorized in writing by Barton-Aschman or the Town of Addison. If you
have any questions regarding the information requested, please do not hesitate to call. Sincerely 􀁂􀁁􀁒􀁔􀁏􀁎􀀭􀁁􀁾ASSOCIATES, INC. /-(l. ,􀁾􀁾􀀮􀀠'. 􀁒􀁾􀁗􀁵􀁮􀁤􀁥􀁲􀁬􀁩􀁣􀁨􀀻P. Vice
President Principal Associate 􀁾􀀠cc; Mr. John Baumgertner -Town of Addison [!!.JJ PARSONS • TRANSPORTATION GROUP 
, ,"' WILBUR SMITH ASSOCIATES ENGINEERS. ECONOMISTS. PLANNERS ......--•••••••••. , ........... 135 COLLEGE STREET. P.O. BOX 9412. NEW HAVEN, CT 06534 • (203) 865-2191 • FAX (203) 624-0484
May 13, 1993 Mr. Robert Wunderlich Barton-Aschman Associates, Inc. 5485 Belt Line Road, Suite 199 Dallas, TX 75240 Fax If 􀁾􀁾􀀠:s Dear Mr. Wunderlich: Pursuant to your Authorization
to proceed of March 2, 1993, Wilbur Smith Associates (WSA) has completed a review of the impacts which the Extension of Arapaho Road west of the Dallas·North Tollway would have on the
proposed Addison Airport Toll Tunnel assessment project. The study findings presented build upon the initial feasibility assessment study of the Addison Airport Toll Tunnel completed
by WSA in June of 1991 and the Final Feasibility Report completed in February of 1992 for the Texas Turnpike Authority (TTA). As agreed, WSA has updated the traffic models used in the
earlier study to accommodate certain assumptions made in the proposal. This included modiJYing some roadway capacities in the travel corridor, and developing several different traffic
networks which would accurately portray the three different implementation phases of the Arapaho Extension, as described by Barton-Aschman. All of"er assumptions from the Final Feasibility
Report of February 1992 remain unchanged. A series of capacity-constrained toli diversion traffic assignments were run, including assignments at both 1995 and 2010 traffic levels, as
well as $0.50 and $0,75 toll rates at the Addison Tunnel. The results of the new traffic assignments which incorporated the extended Arapaho Road were then compared to the traffic assignments
originally run in the previous Addison Toll Tunnel study to evaluate the impact that this would have on the forecasted toll 􀁲􀁾􀁶􀁥􀁮􀁵􀁥􀀮􀀠Traffic Modeling Procelllire The first step
involved retrieval of the traffic modeling network used by WSA in AlBANY. NY • ATLANTA. GA • CAIRO. EGYPT. CHARLESTON. SC • COLUMBIA. SC • COLUMBUS. Oi-l • DES MOINES. IA • FALLS CHURCH
VA HONG KONG. HOUSTON. TX • KNOXVlLLE. TN • LEXINGTON. KV • LONDON. ENGLAND • lOS ANGELES. CA • MIAMI. FL • NEENAH. WI NEW HAVEN. CT • OAKLANv. CA • ORLANDO. FL • PrTTSBURGH. PA • PORTSMOUTH.
NH • PROVIDENCE. RI • RALEIGH. NC • RICHMOND. VA RIVERSIDE. CA • ROSELLE. IL. SAN FRANCISCO. CA • SAN JOSE. CA • SINGAPORE. TAMPA. FL • TORONTO. CANADA • WASHINGTON. DC EMPLOYEE·OWNED
COMPANY 
the previous Addison study. This windowed network was originally developed for the northern Dallas region from a comprehensive traffic network supplied to WSA by the North central Texas
Council of Governments (NCfCOG). Modifications were made to the links in both the 1995 opening year network as well as the 2010 design year network:, to ensure consistency between the
network assumptions and the data supplied by Barton-Aschman. A total of 15 different traffic assignments scenarios were then completed, which included alternate tunnel toll rates, alternate
assignment years, and the various phases of the Arapaho Road Extension. For each of the scenarios, traffic assignments were made for the A.M. peak hour, P.M. peak hour, and the off-peak
average hour, which were then combined into an average total daily traffic figure. The impacts that the extended Arapaho Road would have on the forecasted traffic and revenue of the
Addison Tunnel were determined for each planned phase of the Extension. The phasing information was supplied by Barton-Aschman, and assumes the following: • Phase I consists of upgrading
Arapaho Road for the entire length of its existing alignment, ending at Addison Road, and open to traffic on January 1, 1996; • Phase 2 would extend Arapaho on new alignment from its
present junction at Addison Road to Midway Road, and would be completed five to ten years after Phase I; • Phase 3 would extend Arapaho on new alignment from its junction with Midway
Road to Marsh Lane, and would be completed 10+ years after Phase r. For the traffic modeling analysis, WSA used a completion or opening year of January 1, 2000 for Phase II and January
1, 2010 for Phase III. Estimated Annual Revenue Impacts After completing the traffic assignments, plotting and summarizing the results, -2
the new traffic forecasts for the Addison Airport Toll Tunnel were compared to the traffic forecasts developed without the Arapaho Road Extension included in the network. As summarized
in Table A, the Extension of Arapaho Road has a moderate impact on the forecasted tunnel traffic figures. If the Addison Tunnel toll rate is set at $0.50 for all traffic, thecompletion of Phase I of the Extension will have little measurable impact on tunnel traffic and revenue forecasts. Approximately a 10 percent decrease in traffic is forecast upon completion
of Phase II, with an annual toll revenue impact of $347,000. Assuming the entire Arapaho Extension is in place, tunnel traffic in the year 2010 is expected to be slightly over 15 percent
less than originally forecast, with $712,000 less annual toll revenue realized as a result. Under the $0.75 toll forecasts, the completion of Phase I will also have a negligible impact
on tunnel traffic and revenue. When Phase II of the Arapaho Road Extension is completed in 2000, it would result in an estimated 15 percent drop in the average daily traffic using the
Addison Airport Toll Tunnel, with a corresponding decrease in annual revenue of slightly over $600,000. When the full construction of the Arapaho Road Extension is completed to Marsh
Lane and evaluated in terms of its impact on the design year traffic, approximately 18 percent less traffic can be expected on the Tunnel, with a corresponding drop of $985,000 in annual
revenue. The extension of Arapaho Road will have the greatest impact on the future traffic levels of the BeltIine Road. Aithough some traffic diversion is expected on the other major
east-west arterials in the study corridor, most of the impacts will occur between Arapaho Road and Belt Line Road in the area studied. Rather than directly competing with the Addison
Toll Tunnel, the Arapaho Road Extension's primary impact will be to improve conditions on the Belt Line Road, thus making Belt Line Road more competitive with the proposed Tunnel. During
the course of quantifying the impacts which Arapaho Road would have on the Addison Toll Tunnel, the most current, accepted professional practices and -3
Table A ESTIMATED TRAFFIC AND REVENUE IMPACTS ON ADDISON TUNNEL From Extension of Arapaho Road ADDISON TUNNEL TOLL OF $0.50 PHASE OF ARAPAHO ROAD EXTENSION Pbase I Phase II Phase III
Phase I Phase II Phase III EXPECTED COMPLETION DATE 1996 2000 2010 1996 2000 2010 Original Forecasts Modified Forecasts Total Impacts Average Annual Average Annual Average Annual Daily
ToU Daily Toll Daily Toll Traffic Revenue Traffic Revenue Traffic Revenue 14,200 $ 2,592,000 14,200 $ 2,592.000 18,600 3.395,000 . 16,700 3,048,000 (1,900) $ (347,000) 25,500 4,654,000
21,600 3,942,000 (3,900) (712,000) ADDISON TUNNEL TOLL OF $0.75 11.600 S 3,176,000 11,600 S 3,176,000 14.400 3.942,000 12,200 3,340,000 (2,200) $ (602,000) 19,800 5,420,000 16,200 4,435.000
(3,600) (985,000) WILBUR SMITH ASSOCIATES May 13.1993 
procedures were used. However, there are sometimes differences between forecasted and actual results caused by events and circumstances beyond the control of the forecasters and these
differences could be material. * * * WSA has sincerely appreciated the opportunity to continue working on such an important project concerning the future of the Town of Addison. Please
do not hesitate to contact us if there are questions or if we can continue to be of service. Thanks and best regards. Very truly yours, WILBUR SMITH ASSOCIATES 􀁾􀁤􀁬􀀢􀁙􀀧J, J/;<Associate
JS/lao cc: Mr. James W. Griffin -TTA -5
BARTON-ASCHMAN ASSOCIATES, INC. 5485 8e.t Litle Road. Suite 199. DC':!!as, Texas 75240 USA. (214) 991-1900. Fax: (214) 49C·9261 MEMORANDUM To: Ron Whitehead From: Gary Jost Kathi Mullins
Date: May 5, 1993 Subject: Analysis of Keller Springs at Dallas North Tollway, Addison, and Midway Purpose The purpose of this memo is to document the analysis of the operating conditions
at the intersections of Keller Springs at Dallas North Tollway, Keller Springs at Addison and Keller Springs at Midway after implementation of the Airport Toll Tunnel. These intersections
will support the proposed toll tunnel and are important to the success and efficiency of the tunnel. Traffic conditions at the study intersections will be dependent upon total traffic
volumes, intersection configuration, and traffic signal timing efficiency. Total traffic volumes will be comprised to traffic utilizing the toll tunnel and background traffic, or traffic
on the roadway system that does not use the tunnel. Analysis Traffic volume projections for the toll tunnel were prepared as part of the feasibility study for the year 2010. To develop
background traffic for this design year, a growth rate of 13% was applied to existing turning movement volumes. The projected year 2010 AM and PM peak hour turning movement volumes without
the toll tunnel are depicted in Figure 1. Toll tunnel site volumes were taken directly from the feasibility study. It is anticipated that 1,850 vehicles will travel through the tunnel
in the AM peak hour and 2,200 vehicles in the PM peak hour. These volumes are based on the $.75 toll scenario. The toll tunnel volumes were added to the projected year 2010 turning movement
volumes to get the projected year 2010 with toll tunnel scenario shown in Figure 2. Intersection level of service (LOS) for signalized intersection is determined by average delay, in
seconds per vehicle, experienced at the intersection and is a function of the volume, capacity and amount of green time allocated to each movement at the intersection. Capacity is a
function of the number of lanes, the type of movement and the make-up of the traffic in that movement. The methodology used in this study for determining capacity, delay and LOS 􀁛􀁾􀁊􀁐􀁁􀁒􀀵􀀰􀁎􀁓�
�-TRANSPORTATION GROUP 
--ADDISON AIRPORT '".. 􀁾􀀠o t.c; c o 􀁾􀀠-o z" '0 ...."« .......;>, -;. o􀀢􀀧􀁾􀀠.... 􀁾....,'"0>0,.:>....􀁾􀁾􀁾􀀠.. ",0"'0>--; ... ..-'".... u>'" ..."'<P...v '" '" 0'"􀁾􀀢􀀧􀁏􀀠'-.4/46
􀁑􀁾􀁾􀀠'-149/408 􀁯􀀻􀀢􀀧􀁾􀀠4811208\\\ '_4/42Keller Springe ,.,.... 15149 "'II ;!t9/262 14/43􀀩􀁎􀀻􀀽􀀥􀁾􀀯􀀱􀁬􀀡􀀴􀀠Keller S rln a j",.... '-761/336216/379..J1 , .. :\,<1 0/1<;;9'-""7'.C-:-..T\17(
31120-\ \\\ 102/181,12189-"" '1 (0110_\ \'643/234...... 􀁾􀀢􀀧􀁯􀀢􀀧... 4/16' ..... '" 164/602 248/242 ...... " 􀀭􀀮􀀢􀀢􀁾-_....Ij\ -"'... ",,,, '" "'0-....co"'...􀁾􀀠"'-... , ..' ....
.,.... '" "'''' ",,,,0'" "'... .. ........ W I Nol to Scale 􀁾􀁁􀀮􀁍􀀮Peak Hour/I P.M. Peak Hour XXX/XXX FIGURE 1 PROJECTED YEAR 2010 TRAFFIC VOLUMES WITHOUT TOLL TUNNEL I 􀁾􀀠 
ADDISON AIRPORT o.. c: ".., « ",'""0 􀁾􀀹􀀯􀀲􀀵􀀲􀀠14/43 Kelle, S rln .. 􀁁􀁾􀀠,-􀁾􀀶􀀴􀀵􀀯􀀵􀀳􀀲􀀠393/382 -...A 'Itt Keller S 593/991 --.... 10 1/154 􀀢􀀧􀁾􀀠... 398/378.,<11.,......
.... 􀁾.... 􀁾􀀬<II <11",,0.,..... .... ..... .."' ..0",0 ... ...._ -'" ..0" "''''''' ,.. .. 􀁾􀀠Q l-e o 􀁾􀀠-z .. .. .. t:l 707/976 􀁾􀀠I Not to Soale r--::::.. A.M. Peak HourI /P.M.
Peak Hour XXX/XXX FIGURE 2 PROJECTED YEAR 2010 TRAFFIC VOLUMES WITH TOLL TUNNEL " 􀁾􀀠
Analysis of Keller Springs at Dallas North Tollway, Addison, and Midway June 9, 1993 Page 2 , at an intersection is outlined in Chapter 9 of the nationally recognized and accepted Highway
Capacity Manual (HCM). Level of service is a qualitative measure of identifying how effectively traffic is managed at an intersection and is defined by Categories A through F. Table
1 provides descriptions for each LOS for signalized intersections. For planning purposes, LOS D conditions are considered acceptable. A and B No delays at intersections with sooth progression
of < 15.0 traffic. Uncongested operations; all vehicles clear in a single signal cycle. C' Moderate delays at intersections with satisfactory to good 15.1 to 25.0 progression of traffic.
Light congestion; occasional backups on critical approaches. D Forty percent (40%) probability of delays of one cycle or 25.1 to 40.0 more at every intersection experiencing "D" condition.
Significant congestion on critical approaches, but intersectiona! function. Vehicles Vehicles required to wait through more than one cycle during short peaks. No long standing lines
formed. E Heavy traffic flow condition. Delays of two or more cycles 40.1 to 60.0 probable. No progression. Limit stable flow. Blockage of intersection may occur if traffic signal does
not provide for protected turning movements. F Unstable traffic flow. Heavy congestion. Traffic moves in > 60.0 forced flow condition. Three or more cycles to pass through intersection.
Total breakdown with stop-and-go operation. Capacity analyses were performed for the signalized intersections at Keller Springs and Dallas North Tollway, Keller Springs at Addison, and
Keller Springs at Midway. The analyses were performed for the projected base condition (year 2010 without the toll tunnel traffic) and projected year 2010 with the toll tunnel traffic
to provide an additional basis for comparison of any impacts associated with the toll tunnel's development and to identify any change in level of service which may be anticipated as
a result of normal growth in areawide traffic volumes over time. The results of these analysis are presented in Table 2 on the following page. 
Analysis of Keller Springs at Dallas North Tollway, Addison, and Midway June 9, 1993 Page 3 Dallas North Tollw"v • Addison B 13.3 c 17.3 o 8.1 D 38.9 c 23.6 F 82.8 􀁾􀀠Del not at these
levels of congestion. F • F • Based on the intersection analysis performed Keller Springs at Addison and Keller Springs at Midway operate at acceptable levels of service for the projected
Year 2010 volumes without the toll tunnel. Keller Springs and Dallas North Tollway operates at LOS F for projected Year 2010 volumes without the toll tunnel during the PM peak period.
Keller Springs at Dallas North Tollway, Keller Springs at Addison, and Keller Springs at Midway all operate below the acceptable levels of service for projected Year 2010 volumes with
toll tunnel volumes •. Roadway improvements are recommended at these intersections in order to maintain the base line level of service with the toll tunnel. The improvements include:
Keller Springs at Midway • Widen north, west, and south approaches to provide dual left turn lanes. • Widen east approach to include a left, two through, and right turn lanes. • Provide
right turn lanes on the west and south approaches Keller Springs at Addison • Widen west approach to provide a left, two through, and a right turn lane. • Widen the east, south and north
approaches to provide dual left turn lanes. Keller Springs at North Dallas Tollway • Extensive improvements are needed for northbound frontage road and southbound frontage road intersections
to operate at acceptable levels of service and will need further analysis. The intersection analysis' results with the recommended roadway improvements incorporated are shown in Table
2. Figure 3 shows the recommended roadway improvements. 
I UO$IPPV z o til C C < Ia: o Il. a: < 􀁟􀀭􀀽􀀽􀀽􀀬􀀻􀀺􀀻􀀻􀁺􀁾􀀺􀀮􀀲􀀺􀀠.." -􀁾􀀠'" --z'" (') 1.11 a: ::I Cl u:: '" c '0 .... :;: '" .. " -" '" 􀁾􀀠III Il. t t 0 CI) 􀁾􀀠UJ I0 Z Z UJ
UJ::: ::: UJ:::> 00 ocr: UJOo cr:::: >« s: o « o cr: 
Analysis of Keller Springs at Dallas North Tollway, Addison, and Midway June 9, 1993 Page 4 Conclusions In order for the toll tunnel to be successful and efficient, the intersection
of Keller Springs at Midway: Keller Springs at Addison, and Keller Springs at Dallas North Tollway must operate at acceptable levels of service and should be designed to meet design
year traffic demands. Roadway improvements recommended to maintain the base line level of service for Keller Springs at Addison and Keller Springs at Midway have been outlined in this
memo. Keller Springs at Dallas North Tollway will need extensive roadway improvements to operate at an acceptable level of service and will need to be analyzed further. c:\wp\kathi\tolltunn.mem

i ................. I 􀀬􀁾􀀠 . ".... " '. HAYNES AND BOONE, l.L.P. ATTORNEYS ANO COUNseLORS AT I.A'N """ImS t1OIEC'l' OIAL_, r 2141651-5600 February 26, 1993 􀁾􀁡􀁹􀁾􀁥􀀠Gl • P.E. The
nn ration ..􀀢􀀭􀁾􀀮􀀮􀀠Consul Engineers17103 ton Road SuH 05 '" Oal $. Texa" 75248 Re: Addison AIrport Tunnel we reprllSint CB Instltutlonal Fund VII. the owner of the multl-bulldlng
office project at the northeast c:orner or the intersectIon of Ke ller Spri ngs Road and MIII"ay Road (the "Property"). As I ment\oned In 0\.11" telephone 􀁾􀀠dIscussion or last week.
our client is 􀁡􀁴􀁴􀁥􀁭􀁰􀁴􀁾􀁮􀀹􀀠to obtain as much informatIon as POSSIble regarding the possIble Impact of tlte Addison Airport TunJ1f1 on the Property. In our dhcusslon or last
weell:. you Indicated you would contact Mr. Jim Griffin of the Texas Turnpike Authority to detel'1ll!ne whether the Turnpike Authority would object to the release of the estlmatl!d rIght-or-way
acquBI tlon cost a$ It relates to tbe Property. U spok.e to Mr. Jim Grlt'fin today IIho indIcated thts Information is not al/allable to the public). However. if the Turnpike Avthorlty
dots approve the release of this 'Informat1on, r would apprec 1 ate "your sending It to lIIe at the address 1 isteel above. If the Turnp\ke Autltority dectlJ1fs to authorize the release
of th1s 'nf'ot:natlor:'. l:would Ilpprectde your CQIlf'mtng thl& In wdtlng, to 1119 as \<911. Please plaee my rtaIIIe and address on your mailing' lht "for any I'vrther 􀁣􀁏􀁍􀁭􀁵􀁮􀁾􀁣􀁡􀁴􀀱􀁯􀁮􀁳􀀠
that relate to this prolect. Thanks In idVancl for your help. Sincerely.{Zwt 􀁁􀀮􀁾􀁕􀀮􀁴􀀠Robert A. McCulloCh RAH:TtlIlI ld47Zilll TOTAL P.01 
I I TOWN OF 􀁁􀀮􀁄􀁄􀁉􀁓􀁏􀁎􀁾􀀠TEXAS SERVICE CE.:.VfER FA.." 􀁾􀁏􀀺􀀠(214) 931-6643 FROM:_ k G:\TO: 6q('j Sos I DEPT: -JD V\ &4 <'h;jQrT/')'f,,COl\IPA.NY: -;:)3,Q d 􀁾􀀬􀁊􀀠A &' tll'l"
itJ 0.1-/c;.·'1jliJ1I.f(PHONE: '7 SO -d (56I F,LX :.'«J1\IBER: ( DATE: )IUl\IBER OF SHEETS \inducl.ing cover sheet/:I ICOl\:lME;,"'ITS: 
**--IND. XMT JOURNAL No. DATE/TIME DURFlTlON COMM. RESUL.T PAGECS) MODE DESTINATION RECEIVED lD RESOUJT I ON JOURNAL-__ =32 = 03-03-1993 08:20AM = 00:01'03 OK 002 TRANSMISSION = 4909261
=STD DATE 03-03-1993 ,.*.,.** TIME 08:23AM ****** -TollJll of Addison 214 248 7814-************ 
DALLAS COUNTY KVl0193 PUBLIC WORKS February 23, 1993 Mr. Ron Whitehead, city Manager Town of Addison 5300 Belt Line Road P. O. Box 144 Addison, Texas 75001 RE: Keller Springs Road Project
490-407 (Midway Road to Addison) Addison Airport Tunnel Preliminary Alignment Dear Mr. Whitehead: Howard Needles Tammen and Bergendoff (HNTB) , design consultant for this project, has
submitted the attached drawing titled Figure 3. Though preliminary, this drawing is suitable to define the project limits and approximate rights-of-way. The final calculated alignment
has not been made, but will be based upon this preliminary alignment and profile. The city is encouraged to acquire or reserve right-of-way for the construction of the project if the
opportunity presents itself. If you wish to discuss this further or need additional information, please call me at 653-7151. 􀀱􀀷􀁌􀀱􀁾􀁾􀀠Allen Bud Beene, P.E. Director of Public Works
ABB:TRK:rem 􀁾􀀠cc: Jim Jackson, Commissioner, Road and Bridge District No. 1 Attachments ftle:4a#4a#lS:b.lnnd.407 411 Elm Street Dallas, Texas 75202 653-7151 
.Jru6 One Galleria liY,lier /3J PD 1nS5 Noel Road. LB 3 􀁓􀁕􀁉􀁦􀁾􀀠II}DC 􀁹􀁛􀀬􀁾􀀳􀀠JDPDalla•• TX 75140,6603 (lI4) 934,2244 FAX (214) 991-5184 􀁾􀀹􀀴􀁻􀁜􀀠West 􀁏􀁲􀁡􀁮􀁾􀁷􀁯􀀺􀁊􀁏􀁊􀀠AvenlJl!
S1.lltl!' 207 <• r Orange, CA 92668aC50 (714) 978·1144 FAX (714) 978·t268 􀁾􀀬􀀠FEB2593 , /';I 1_-Mr. James W. Griffin Deputy Director (/LTEXAS TURNe P. O. Box 69 Dallas,. as 􀁾􀀷􀀻􀀵􀀲􀀡􀀮􀀡􀀱􀀮􀀻􀀻
􀀹􀀭􀀰􀀳􀀶􀁾􀀺􀀡􀀡􀀺􀀹􀁾􀀻􀀻􀀻􀀻􀀻􀀻􀀻􀀺􀀺􀀽􀀭􀁾􀁾􀀠r Addison Airport Dear Mr. Griffin: ------It has come to our attention that construction of the captioned project has been approved.
As property owners directly and severely impacted by the proposed project, we are perplexed by the fact that we received no notices of meetings with respect thereto. The project, as
proposed, adversely impacts our property to the extent that it takes away our Keller Springs access, as well as the fact that if we correctly interpret your drawings, some 25,000 to
30,000 square feet of our property will be required for right-of-way; as our tract is presently only three acres, this would severely limit the potential for development of the site.
We would appreciate the intentions of the Authority regarding these impacts. Please regard this letter as registering our concern to the concept of this project and its impact on the
value of our property. Very truly yours, M & F 􀁾􀁥􀁮􀁴Company, By: -i:-__ -<_ cc: G\tJ0 􀁃􀁴􀁊􀁲􀀧􀁰􀁄􀀨􀀧􀁡􀁾􀀠􀁉􀁾􀀠t B· r d 􀁉􀁾􀁾􀀧􀀠Will lle ... 
IIlr. Donald Lookadoo stating his COncerns with the project. You will note from the attached exhibits that he is referring to property at the nort}!west corner of Dooley Road and Keller
Springs Road. ln regard to the second item in his letter, I am not sure that the property will be denied access or frontage to Dooley Road. In fact, he may be able to gain square footage
to the total property by our relocating Dooley Road. In regard to Item 3, we need to determine what that assessment covered, has that assessment been paid and been invested in Keller
Springs Road improvements by Addison or has it been held in eScrow for future paving improvements to Keller Springs Road. I am sure you can clarify this point for us. If the assessment
has been collected and expended, a copy of the legal assessment agreement for this property could be useful to us. Thank you for your assistance. ours very ___-4awMU}J, ' '"mes W. Griffin,
eputy Director ( cc: The Ginn Corporation Enclosure nlg Mr. Ron Whitehead City Manager Town of Addison r.o'. Box 144 Addison, TX 75001 Dear Ron: Pursuant to statements made at the recent
Airport Toll Tunnel, I am forwarding you 3015 lWelgh Street· p.o. Box 190369 Dallas, Thxas 75219 PIIone 2141522-6200 'ax 2141528·4826 Febru8ry 16, 1993 r fEB1793 I, ,,l ..J public hearing
on the Addison a copy of a letter received from Ml!!IllBBS, L!lTlIER G. JONES, jl!" ClIAmMAN. CORPUS CHRISTI' MlCIWi1 Y. CHOU. VICE C1IAmMAN, HOUS11)N RAY C, STOKER. jl!., ODIlSSA •
HENK't' R. MUNOZ. m, SAN ANroNIO • JAMES N. MUNS, PLANO' CllVS RONNEILS. HOUS11JN DAVID B. BERNSEN. BEA!JMONT • )ERE W. THOIlPSON, jl!.• DAl.Ll.S • WIU.LIM MAHWlES, JR., DAlLAS • RAIlL
A. BEST£IIO, JR., BROWNSVlLI..E NA'l'II8LYNB A. KENNEDY. HOUS11JN • PHHJP MON'l'OOMllRY. DAlLAS • JOlIN II. RAMMING. EXECUTIVE DlREC11JR • DARBY KAIlLllll.. SBCRBTARY·TIlIWlIJRER 
---􀁾􀁅􀁂􀀭􀀱􀀵􀀭􀀱􀀹􀀹􀀳􀀠09:59 P.01I I I I 􀁾􀁾􀀠 P.O. bS98 􀁁􀁤􀁤􀁬􀁾􀀮􀀠TX 75001 (214) 931·7127 Name: Company: 􀀧􀀢􀀧􀁾􀀧􀀮􀀮􀁉􀀭􀀭􀀽􀀭􀁟􀀮􀁷􀀮􀀮􀀡􀀡􀀡􀁾􀁾__ FAX No.: I I 1 i i PAX
TRANSMITTAL I FElJ159311.. --.1DBLlVER TfiE FOLLOWING PAGES TO: FROM: 8.1tIA."i.t<.􀁾􀁳􀀮LL(214) 931-8398 Location: 􀁽􀁾________ Date: Total Number of pages FAX No.: 􀁾􀀠4100 -1􀁢􀁾􀀧􀁴􀀠Including
Cover Sbeet: "'1 If you do 􀁬􀁾􀁴􀀠receive all of the pages. please contact us as sron as possible. ;1 i MESSAGEi f'f: Co\M-Me,,,,,-r2 ----lo -r-􀁾􀁾􀀮􀀴c::.. I JUaN 'P1'tC\.-􀁁􀁉􀀩􀁜􀁾􀁴􀀾􀁾IT)'"
I II CONt:.. 􀁾􀂣􀁎, f\...(..", -C􀁾􀁇􀀮􀀭er""OD J 􀁾􀁏􀀮􀀮􀀮􀀮􀁊􀀠.j tV1\,.1\.4-L ,41\1 I) EllVI.\. , .IV􀁾􀀠II';A-I'i J t>t:::. CoN/t'2o I ) f I) Ace.i SC; y==ye 0"""''I 􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭�
�􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭:J " j :r 1 UQuality Source Sampling" I 
P.02 9EB-15-1993 09:59 James Griffin ty D1l'ector Turnpike Authority • Box 190369 ,Texas 75219-0389 I Df Mr. Griffin: Dill Thursday. February 11th, I attended the public hearillg at
the Addison cference Center concerning the Addison Tunnel. : 􀁆􀁾􀀠the benefit of several parties. I wmlld like to ex:pNss the concerns Of,lMETCO Environmental regarding the tunnel design
􀁾􀁮􀁤􀀠its effect on 'company:in pal'ticuJar. l:1 1. No notification was sent to the property owners ' affected by the tunnel. Therefore, tlie public . ; l hearing needs to be reconvened
after :>r0p91' if notification has been sent to surrounding OWlIel'S. I 2. METeo Environmental purchased the Pr0p9?ty ati 16115 Dooley Road and built its corporste J.ffices ! with the
main consideration that the COMpany vehicles, visitors and employees would have acness to a controlled intersection at Midway Road and Keller Springs. The tunnel plan elimina.tes any
controlled access to 􀁍􀁩􀁤􀁾􀁹􀀠Road for METeO Environme.lta1. 3. The tunnel design will impose a hards:bip on!.' companies a.nd land owners along Dooley and Keller , Springs by eliminating
any controlled accnss to , Midway Road.. I P.O. 􀁂􀁯􀁾􀀠598 , Addlson. TX 7􀀵􀁏􀁾􀁌􀀠(214) 931-7127' FAX \214) 􀀹􀀳􀀱􀀭􀁡􀀳􀁾􀀠Field Qffios, 1 Hou;lOn, TX ; #.., •." tfC" ""..,"''''
J 
P.03 CEB-15-1993 10:00 Mr James Griffin Fe ry 15, 1993 Pa Two i A severe safety hazard will be ereated for NiETCO'f 4. , Environmental's employees, visitol'S and 􀁤􀁲􀁩􀀧􀁖􀀧􀁾􀁬􀀧􀁓􀀠of
oar Ii ton vans and cargQ Vans in attempting to cross Midway Road without the help of controUedlCOOSs due to the eUnrination of access to KeUer Spri ngs • I 5. METeo Environmental's
property value will be impacted due to the elimination of controlled lCcess to Midway Road. . s. In regards to the Toll Plaza location, it.s the feeling of METCO. Env:ironmental tbat
east bound traffic will back-up into Midway Road ereamg a traffic problem. The Toll P1aza needs to be moved further east on Keller Spl'ings or relocated. ! '1. In addition, the tunnel
entl'BIlce on the east Ilide of the ail'llOl'1: needs to be moved east of Addison Road where traffic is lighter rather than dumpirg the traffic onto Addison Road • ., In isummary. METeO
Environmental is not opposed to tle concept of the tUlmel. !IS 10ng as the Jogistica1 impact on the company is el:iarinated. ! 􀁓􀁾􀁲􀁥􀁬􀁹􀀮, ··""7·A " /EIlp Powell Human Resources
I EWds,., 'i .1 " ,, ; ., :;, 
Fepruary 15, 1993 Mlij. James Griffin DefJUty Director T"as Turnpike Authority p 􀁾􀁾􀁾􀀠.Box 190369 ' D , s, Texas 1:;219-U369 DeF Mr. Griffin: Or· Thursday, FebPlIary 11th, I a.ttended
the public hea.riHg at the Addison ec.nrerence Center concerning the Addison Tunnel. FOj:' the benefit of several parties, I would like to expr M>S the concerns of iMETCO Environmentai
regarding the tunnel design l·nd its effect on oUf company in particular. 1. No notification was sent to the property f Iwners affected by the tunnel. Therefore, tne public hearing needs
to be reconvened after ,Jroper notification has been sent to surrounding OWl ,ars . 2. METeD Environmentai purchased the prope'ty at 16115 Dooley Road and built its corporate )ffices
with the main consideration that the cc wpany vehicles, visitors and emploYl*'s would have ac Jess to a controlled intersection at Midway Road and Keller Springs. The tunnel plan eliminates
any con trolled access to Midway Road for METeo Environme ltaJ. 3. The tunnel des:ign will will impose a hardsMp on companies and land owners along Dooley and Keller Sprine:s by eliminating'
any controlled ace, !SS to Midway Road. " , P.O. lSox 598 ; Addison. TX 7500, (214)931-7127J. FAA (214) 93H3.::st Fletd office; ,i Houston, TX , (713) 869-73721, 
Mr·: James Griffin Fe'ruary 15, 1993 P£l/fe Two 4. A severe safety hazaI'd will be created for lHETCO Environmental's employees, visitors and drivaI'S of our 5 ton vans and cargo vans
in attempting t< cross Midway Road without the help of controlled :lccess due to the elimination of access to Keller Spr:ngs. 5. METeO Environmental's property value Vi ill be impacted
due to the elimination of controlled !l.ccess to Midway Road. 6. In regards to the Toll Plaza location, it is the feeling of METCO Environmental that east bound traffic will back-up
into Midway Road crea ling a traffic problem. The Toll Plaza needs to be moved further east on Keller Springs or relocated. 7. In addition, the tunnel entrance on the east . ;ide of
the airport needs to be moved east of Addisoll Road where traffic is lighter rather than dumpUlg the traffic onto Addison Road. In .summary, METCO Environmental is not opposed to tl
,e concept of the tu:mel, as long as the logistical impact on the company is eJ.iurlnated. Resources EJ'4/ds i I j TOTAL P.03 
DONALD E. LOOKADOO P.O. Box 515496 OFFICE: (214) 450-8610 DALLAs! TEXAS 7e251'5496 FAX: {214} 􀀴􀁾􀀸􀀭􀁡􀀲􀀸􀀴􀀠February 12, 1993 Mr. James W. Griffin Deputy Director Texas Turnpike
Authority P.O. BoX 190369 Dallas, Texas 75219-0369 RE: Addison Airport Tunnel Dear Mr. Griffin: EKL Realty Partners owns 75,967 square feet of land located at the northwest corner of
Keller Springs Road and Dooley Road in Addison, Texas. The "conceptual design" of the Addison Airport Tunnel adversely impacts the value of this property because: 1. The property currently
has access and frontage on two streets, Keller Springs Road and Dooley Road. 2. The conceptual design shows no access on Keller Springs Road and the relocation eastward of Dooley Road,
which would then deny this property both frontage and access on Dooley Road. 3. This property has paid a $55,827 paving assessment for the improvement of Keller Springs Road, which will
no longer be accessible to this site. This property is outlined in red on the attached exhibits consisting of a plat and the conceptual design. !'Je '.viII appreciate your consideration
of the severe adverse impact on the market value of this property due to the proposed Addison Airport Tunnel. -.sincerely, 􀁾􀁒􀁅􀁁􀁌􀁔􀁙􀀠PARTNERS (jJ£t?> -;?« ., Donald E. Lookadoo
'. .. ... 􀁾􀁦􀀧􀀭􀀻',.:: 􀀬􀀭􀁴􀁾􀀠: A:\93044 'I .!," '::< f ; 
, :: o MIDWAY RD. PVJ eTA. , • .,.'0 llil..y, ea&.oo '100'...0 <t TOLL PI.,lZA,'-( -􀁾􀀠----\ \ \ \ \ , , \ . \ .' ",', , , \ \! \ \, \ \ -' 􀁒􀁅􀁾􀁏􀁏􀁁􀁔􀁅􀁄􀀠, . R 􀀻􀀿􀁾􀁩􀁉􀁎􀁑􀀠􀁗􀁁􀁩􀁾􀀠'.
,! 􀀮􀁾􀀢􀀡􀀮􀀠: , WIUIT PORT1..1.. STA. 9+75 It, DOOLE Y RLI. (HORrln -__...1 􀀡􀀩􀁏􀁏􀁾􀀧􀁅􀁙􀀠1'10. f;vDJIL \ \ ......,,-;----10 
,./". ,.'. L.!? ?!i?!i '. '.' , I .'5154---' ,. , ,·/7& :;5.t?! )-----1--:. 􀁾􀀬􀀠.􀁾􀀬􀀠􀀻􀀮􀁾􀀠,'.. ' 􀁾􀀠',' ., .... . ..., ,. ::. , '. . .' . ' :,.: . ' 􀀮􀁾􀀧􀀬􀀠'," 􀀶􀁾􀁾􀁾􀁾􀀧􀁡􀀧􀁾􀀭􀁾􀀭􀁾􀀭
􀁾􀁣􀁾􀁾􀁾􀁾􀁾􀁾􀁾􀁾___􀀧􀁾.• '. -! . " '. ,:' h"' • .,.---'--.t.... .•.....:... -,-'-'􀁾􀀭􀀬􀀮􀀬􀀧􀀮􀀧..:.....,'{)rnaq.,·,(lEEY ..', . 􀀺􀀬􀀮􀁾􀀬􀀧􀀮􀀠,;. . '",: 􀁾􀀬􀀮􀀠':: 􀁾􀀧􀀮􀀢􀀬􀀻􀀢􀀠."
-.'.' 􀁾􀀠. .,-.,'.I' ','! ... :. . -.. '; . . .. r·· CURVE DArn INNcR Cf/TeR IIVNe'!? 
1 FEBog93 FAX TRANSMITTAL from (214) 404-9721 ;;;; c::; TO: FAX NUMBERI 􀁾􀀭􀀲􀁷􀀾􀁬􀁺􀁃􀀠 DATE: RE: MESSAGE: PaC)es to Follow: DALLAS REGIONAL MOIULITY COALITION 12655 N. CQlllrll1
Expw)'. Spill! 820 Dallns. TX 75243 
I • • • • • • • • • • i I t i!i q LN ; leAL! ADDISON AIRPORT TOLL TUNNEL LOCATION MAP o.tIlTlij. WILBUR SMITH ASSOCIATES FIGURE 2 
3015 Rldelgh Street. P.O. Box 190369 llaIlas, Texas 75219 Pbone 2141522-6200 F.. 2141528-4826 January 8, 1993 r Mr. Ron Whitehead City Manager Town of Addison P.O. Box 144 r·-"J' 􀀮􀁾􀀮􀀧􀀠I
Addison, TX 75001 Dear Ron: I thought it advisable to record principle elements of the discussion held at 3:00 p.m. on December 22, 1992, in the Addison Town Hall exploring parameters
for financing of the Addison Airport Toll Tunnel (the "Tunnel") and the sequencing of actions needed to prepare a revenue bond issue for marketing. In attendance at the meeting were
Richard Litton and David Medanich of First Southwest Company, Gary Jost and Bob Wunderlich of Barton-Aschman Associates, Inc., Ron Whitehead of the Town of Addison ("Addison"), and James
Griffin of the Texas Turnpike Authority (the "TTA"). stated Position of the Texas Turnpike Authority. 1. Civil engineering studies, traffic and revenue analyses and financing investigations
suggest, that with a $3,000,000 investment by Dallas County for right-of-way acquisition, the Tunnel is feasible based on revenues projected from a basic $ .75 toll. 2. All parties involved
in the Tunnel study believe a $·.50 basic toll will be more acceptable to the public and will result in increased traffic volumes using the Tunnel. 3. First Southwest analyses have indicated
that $4,000,000 of capital contribution by Addison would, based on a $ .50 toll, provide acceptable debt coverage ratios for the reduced capital cost of the TunneL 4. The TTA staff is
of the opinion that a Tunnel bond indenture could provide for the establishment of a surplus fund whose proceeds would be dedicated to repayment of capital loans to the project by Addison
and Dallas COunty, $4,000,000 and $3,000,000, respectively. MI!MBIlI!S, LUTIIEIt G. JONES, JR., CIIA!lIMAN. COIll'llS CIllllSl'l • MICHAEL Y. CHOU, VICE CIIA!lIMAN. HoosroN RAY c. srom,
JR., ODESSA' IIl!NIIY R. MUNOZ, m, SAN ANl'ONlO • JAMES N. MlINS, PLANO • CI.lI'E RtrNNIlLLS. NOusroN DAVID E. BERNSEN, BIlAUMONT • )ERE W. TBOMl'SON, JR., llALUS • WIl.!.IAM MAlIOII1IS,
JR., llALUS • I1AllL A. BIlSl1!IiO, JR., BROWNSVlLLll NATIIELI'NE A. KENNEDY, HousroN • PIllLlI' MONIOOMBRY, llALUS • JOHN B. RAMMING, IIXIlC!FIlVI! DIIII!C11Jl! • I!AIlIY KABLI!ll,
SECRmRI'·TRIlASURER 
Mr. Ron Whitehead Town of Addison January a, 1993 Page 2 of 4 5. There does not appear to be a reasonable right-of-wayacquisition plan nor practical roadway design geometry along Keller Springs Road west of the Dallas North Tollway (the "DNT") which would physically allow the ·connection of the Tunnel
to the DNT. In order to use surplus funds of the DNT to construct the Tunnel or to provide financial security for the Tunnel bonds, extensive deliberations among staff, consultants,
and attorneys must be pursued to attempt to identify a logical interpretation of the DNT Trust Indentures and applicable law that would permit the Tunnel to be considered an extension,
an enlargement, or an expansion of the DNT. G. CUrrent law does not permit the pledge of surplus DNT revenues to another project unless additional bonds are issued for DNT funding or
for refunding existing bonds. The 73rd Legislature could, however, enact legislation allowing surplus DNT revenue to be used to assist in financing or in providing security to the debt
of other turnpike projects. 7. Based on their experience in revenue bond financing, the staff and consultants of the TTA believe the market for Tunnel revenue bonds is highly suspect,
given the Wilbur Smith Associates ("WSA") report dated February 1992, unless the Town of Addison (i) contracts with the TTA not to construct nor permit to be constructed a Tunnel competing
parallel thoroughfare(s) between Belt Line Road and Westgrove Road from Addison Road to Midway Road during the bonded indebtedness of the Tunnel or (ii) Addison would contract with the
TTA to guarantee the payment of any debt service shortfall of the Tunnel should Addison construct a parallel competing thoroughfare(s) during the life of the bonded indebtedness of the
Tunnel. a. Lease/purchase, licensing, or refinancing of the DNT by Dallas County, conceivably, would permit, subject to support of the Dallas County Conmrl.ssioners, financial support
of the Tunnel from surplus funds of a single county-wide turnpike corporation. 9. County Judge Lee Jackson has suggested in negotiations with the TTA that the County turnpike corporation
would retain the current staff of TTA and desires that that staff and its consultants continue their efforts to develop and finance the Tunnel. 10. The TTA staff and its financial advisor
plan to make a Tunnel progress report to the TTA Board of Directors (the "Board") on January 22, 1993. A Resolution from the council of the Town of Addison supporting the Tunnel, conmrl.tting
a $4,000,000 secondary loan to construction capital, and postponing the construction of a parallel thoroughfare across the Airport property probably would generate Board support for
continuing with the development of the Tunnel. 
Mr. Ron Whitehead Town of Addison January 8, 1993 Page 3 of 4 11. The TTA will authorize WSA to discuss with Barton-Aschman, traffic volumes each firm projects will use the Tunnel. Stated
Position of Addison as Expressed by Addison staff: 1. Addison does not want to abandon its support of 􀁥􀁸􀁴􀁥􀁮􀁤􀁩􀁾􀁧􀀠Arapaho Road from Addison Road to Midway Road. 2. Addison does
not 'deem it reasonable to make up any debt service deficit of the Tunnel should it elect to construct a competing thoroughfare between Belt Line Road and Westgrove Road. 3. Addison
would rather not invest $4,000,000 in the capital cost of Tunnel as it has other useS for that capital. 4. Addison would like to see a physical connection between the DNT and the Tunnel,
thereby allowing surplus funds of the DNT to be used in Tunnel financing. 5. Lacking the implementation of No. 4 above, Addison desires that surplus funds of the DNT to be used to supplement
the capital cost of the Tunnel and/or guarantee any Tunnel debt service deficit. 6. Addison prefers a $ .50 basic toll rate. 7. Addison has no preference for the Tunnel being financed
under the aegis of a Dallas county turnpike corporation or the TTA. In either circumstance, Addison prefers that the Tunnel be financed as a unit of a turnpike system rather than as
a stand alone turnpike project. 8. Addison authorized its traffic consultant, Barton-Aschman, to contact WSA with a goal of narrowing the gap between the two consultants' projected traffic
volumes that would use the Tunnel. Barton-Aschman projects traffic volumes are sufficient to justify both the Arapaho Road extension and the Tunnel in the future. WSA has responded with
a proposal to evaluate the impact of a competing parallel Arapaho Road on the feasibility of the Tunnel. The Addison City Council will consider the WSA proposal on January 12, 1993.
9. Addison feels a two month delay to further evaluate the Tunnel feasibility is reasonable. 
Mr. Ron Whitehead Town of Addison January 8, 1993 Page 4 of 4 The staff of the TTA and its consultants are anxious to receive project and financial support of the Town Council of Addison
for the Tunnel and are prepared to engage in meetings with the staff of Addison as often as may be required to achieve this goal. ours very truly, J "'"--rl(j),uM UJ. ames W. Griffin,
eputy Director cc: John Ramming Luther Jones First Southwest Ginn Corporation nlg 
CITY MA,'lAGER'S OFFICE Post Office Box Hi Addison. Texas 13001 5300 Belt Lin.e Road January 6, 1993 Mr. Jim Griffin Texas Turnpike AuthorityP. O. Box 190369 Dallas, Texas 75219 Dea't'
Jim: I have reviewed your draft of the stated positions of the Texas Turnpike Authority (TTA) and the Town of Addison (TOA). It is important to note a number of items, 1. In Item 7 Page
2 it is stated, "Unless the Town of Addison (i) contracts with the TTA not to construct nor pe=it to be constructed a competing thoroughfare across the Addison Airport (the Airport)
property between Addison Road and Midway Road." The proposed alignment of Arapaho Road does not go across Airport property. The proposed alignment is entirely south of the railroad tracks
and would be in public rights-of-way obtained from private land owners. None of the Arapaho extension is on Airport land. 2. The stated position of the Town are items discussed with·
you by the Town's staff. The Addison City council has not taken an official position regarding the the TTA proposal. In fact, prior to the presentation at the board meeting at the Airport,
town officials had not seen the proposal from Wilbur Smith Or First Southwest Company. We will discuss the proposal with Council at its January 12, 1993 Council Meeting, but we still
have a number of questions. We have supported the concept of a tunnel under the airport, but we want to make sure the proposed scenarios are feasible. We have information from Barton
Aschman that reflects that the Arapaho extension will be needed in addition to the tunnel to address Addison's future traffic needs. We have a proposal from Wilbur Smith to review the
Barton Aschman information. The proposal will take a month to complete and cost $8,456. We will be proposingthat the Council authorize this work on January 12, 1993. The staff feels
that a couple of months delay to answer questions about funding, construction design, toll rates, and the likelihood of the success of the project is reasonable and should not jeopardize
the Texas Turnpike's authorized funding of the project. We will seek council's concurrence on January 12, 1993. 3. Item 2 Page 3, stated position of Addison: "construct a parallel thoroughfare
across the airport property." Again, none of the proposed Arapaho extension is on Airport property. We will want to make a presentation to the Board at your January 22, 1993 meeting
as well as the February 11 Public Hearing if that is permissible. Sincerely, J I . 􀁾􀀠t:::i:.:::f:; ,....-... "' e: 􀁖􀀧􀀭􀀧􀁾􀀠( ;'Ron Whitehead 􀁾􀀭.. City Manager 
:12-30-92 􀀸􀀺􀀱􀀷􀀱􀁾􀀠TX TLR:';'l'IKE ALtH. 􀁾SENT EY:XEROX 7033 􀀢􀁾􀀧􀀮􀀭􀀮􀀭􀀭􀀭._-Admillistralion 3015 Raleigh Street P.O. Box 190369 Dallas. Texas 75219 Phone (114) 522.6200 Fax
No, (114) 52.8-4826 Time'____..8il..i..,􀀱􀀡􀀻􀀮􀀻􀀵􀁾􀁩􀀡􀁬􀀮􀀺􀀬􀀮􀁉􀁉􀁭􀁬􀀮􀀻􀀬􀀬_____ TO: __􀁾􀁒􀁾􀁑􀁕􀁄􀁾􀁗􀁢􀁾􀁩􀁾􀁴􀁥􀁾􀁨􀁷􀁥􀁾􀁡􀁾􀁤􀁵􀀬􀁾􀁍􀁾􀁡􀁮􀁾􀁡􀁾􀁧􀁾􀁥􀁾􀁲􀁾__􀁾􀁆􀁁􀁘􀀺____􀀹􀁾􀀶􀁾􀁏�
�􀀭􀁾􀀷􀁾􀀶􀁾􀀸􀁾􀀴_____________ 􀁃􀁯􀁭􀁰􀁡􀁄􀁹􀁎􀁡􀁭􀁾___􀁾􀁔􀁾􀁨􀁾􀁥􀁟􀁔􀁾􀁯􀁾􀁷􀁾􀁮􀁾􀁯􀁾􀁦􀁾􀁁􀁾􀁤􀁾􀁤􀁾􀁩􀁳􀁾􀁯􀁾􀁮􀁾______________________ FROM: __􀁾􀁊􀁾􀁉􀁾􀁭􀁾􀁥􀁾􀁳􀁾􀀱􀀱􀁾􀀮􀁾􀁇􀁲􀁾􀀱􀀡􀀻􀀮
􀀻􀂷􀁦􀁾􀁦􀁾􀁩􀁬􀀮􀀺􀁮􀁾_____TEL:____________________________ DOCUMENT: (Name/Type) praft leerer recording minutes of Oecember ZZ meeting Number uf pages FAXED: (including coyer sheet)
5 D CONFIDENTIAL 0 Per your requfit [i] for your informalinn D For your approval Handle FileD D ReviewiComment 0 De:ltmy[i] Need answer by 0 ReqW!:!lted by: RoutA! Tn: Additional C ommenlS:
U/JOU it.... any , ..."i",... ,nnctrni"!f th. FAX. /lUlU. C41l12141 522·6201JI. 
214 960 7684::;' 2! 5 " "12-30-92 8: 1at\\􀁓􀁾􀀢􀁈􀀠BY:XEROX 7033 Dec:o.mear 30, 1992 Mr. Ron Whitehead City Mdllager TO\llll of Addison P.O. Box 144 Addison, TX 75001 Dear Ron: I thought
it advisable to record principle elements of the discussion held at 3:00 p.m. on December 22, 1992, in the Addison Town Hall exploring parameters for financing of the Addison Airport
Toll Tunnel (the "'!'".mnel") and the sequencing of actions needed to prepare a revenue bond issue for marketing. In attendance at the meeting were Richard Litton and David Medanich
of First Southwest Company, Gary Jost and !lob Wunderlich of Barton-Aschman Associates, Inc., Ron Whitehead of the Town of Addison ("Addison"), and James Griffin of the Texas Turnpike
Authority (the "TTA"). Stated Position of the Texas Turnpike Authority. 1. CiVil engineering studies, traffic and revenue analyses and financing investigations suggest, that with a $3,000.000
investment by Dallas county for right-of-way acquisition, r.he Tunnel is feasible based on revenues projected from a basic $ .75 toll. 2. All parties involved :i.n the Tunnel study beUove
a $ .50 basic toll. will be more 􀁾􀁲􀀮􀁣􀁥􀁰􀁴􀁡􀁢􀁬􀁥􀀠to the public and will result in increased traffic volumes using the TUnnel. J. 􀁆􀁩􀁲􀁾􀁴􀀠Southwest analyses have indicated
that $4,000,000 of capital 􀁣􀁥􀁮􀁴􀁾􀁬􀁢􀁵􀁴􀁩􀁯􀁮􀀠by Addison would, based on a $ .50 tell. provl.de acceptable debt coverage ratios for the reduced capital cost of the TUnnel. 4.
The TTA staff is of the upinion that a Tunnel bOnd indenture could provide for t.he establishment of a surplus fund whose proceeds wollJ.d be dedicated to repayment of capital loans
to the project by Addison and Dallas County, $4,000,000 and $3,000,000, respectively. 
.!':.'i oj 'A£J,\VA iU,Jv Mr. Ron Whitehead Town of Addison December 30. 1992 Page 2 of 4 5. There does not appear to he a reasonable right-ot-way acquisition plan nor practical roadway
design gearoetry along Keller Springs Road west of the Dallas North Tollway (the "DNT") which would physically allow tho conneotion of the Tunnel to the DNT. In order to use surplu.s
funds of the DN'!' to oonstruct the Tunruol or to provide financial security for the Tunnel bonds. extensive deliberations among staff, consultants, and attorneys must be pursued to
attempt to idenLify a logical interpretation of the ONT Trust Indentures and applicable law that would permit the Tunnel to be conaldared an extension, an enlargement, or an expansion
of the DNT. 6. The 73rd Legislature could enact legislation allowing surplus ONT revenue to be used Lo assist in financing or in prOviding security to the debt of other turnpike projecls.
7. Based on their experience in revenue bond financing, the staff and consultants of the TTA believe the market for Tunnel revenue bonds is highly suspect, given the Wllbl.lr Smitil
Associates ("WSA") <'eport dated Fltbrllary 1992, IlIIless the Tcwn of Mdillon (i) co.o.tracts with tile TTA not to construct nor permit to be constructed a competing thorQ\lghfare across
the Addison Airport (the "Airport") property between Addison Road and Midway Road during the bonded indebtedness of .the Tunnel or (ii) Addison lIKlul.d contra.ct with the TTA to guarantee
the payment: of any debt service shortfall of the Tunnel should Addison construct a parallel competing thoroughfare across the Airport during the life of the bonded indebtedness of the
Tunnel. 8. Lease/purchase, licensing, or refi:nancing nf the DNT by Dallas Col.lnty, conceivably, would permit, subject to support of the Dallas County Commissioners, financial support
of the Tunnel fram surplus funds of a single 􀁣􀁯􀁵􀁮􀁴􀁾􀀭􀁷􀁩􀁤􀁥􀀠turnpike corporation. 9. county Judge Lee Jackson has suggested in negotiations with the 􀁾􀀠lhat the County turnpike
corporation would retain the currant staff of 􀁾and desires that that staff and its consultants continue their efforts to develop and financa the Tunnel. 10. 'l'he TTA staff and its
financial advisor plan to make a Tunnel progress report to the TTA Board of Directors (the "Board") on January 22, 1993. A Resolution from the counci.l of !:he Town of Addison Bupporting
the TUnnel, committing a $4,000,000 secondary loan to construction capital, and postponing tho construction of a 􀁰􀁡􀁾􀁡􀁬􀁬􀁥􀁬􀀠thoroughfare across the Airport property wou.ld probably
generate Hoard support for continuing with the development of the TunnGl. 
Mr. Ron l'Ihitehe"d Town of Addison December 30, 1992 Page 3 of 4 11. The TTA will authorize WSA to discuss with Barton-Aschman. t.raffic volumes each firm projects will use the Tunnel.
Stated Position of Addison. 1. Addison does not want to abandon its support of a thoroughfare parallel to the Tunnel across Airport property. 2. Addison does not deem it rcasonllille
􀁾􀁯􀀠make up any dabt service deficit of the Tunnel should it elect to construct a parallel thoroughfare across the Airport property. 3. Addison would rather nut invest $4,000,000 in
the capital cost at 'I\lnnel as it has other u""s for that capital. 4. Addison would like to sse a physical connection between the 􀁄􀁾􀀠and the TUnnel, thereby allowing surplus funds
of the 􀁄􀁾􀀠to be used in TUnnel financing. 5. Lacking the implementation of No. 4 above. Addison desires that Hurplus funds of the 􀁄􀁾􀀠to be used to supplement the capital cost of
the Tunnel a:nd/or guarantee any Tunnel debt service deficit. 6. Addlson prefers a $ .50 basic toll rate. 7. Addison has no preference for the Tunnel being financed under the aegis of
d Llallas County turnpike corporation or the TTA. In either circumstance. Addiliion prefer" thnt the Tunnel be financed as a un.iL of a turnpike system rather than as a stand alone blrnpike
project. a. Addison authorized its traffic consultant, Barton-ru.chman. to contact WSA with a gual of narrow.1ng the gap between tha two consultants' projected traffic volumes that would
use the Tunnel. 
Mr. Ron Whitehead Town of Addison December 30. 1992 Page 4 of 4 The staff of the Ttl and its consultants are anxious to receive project and financial support of the Town Council of Addison
for the Tunnel and are prepared to engaqe in meetings with the staff of lIAdison as often as may be required to i!.Qhieve this goaL Yours very truly, James W. Griffin, P.E. Deputy Director
cc: John Ramming Luther Jon".. Fi r"t. southwest Ginn Corporation nlg 
--p.a:z 􀁾WILBUR SMITH ASSOCIATES ENGINEemI. ECONOMISTS. PlANNERS 135cou.eGEmm. P,O,SOX9412 • NewHAv;N,CTOO534 • (203)865-2191 .I'AX(203)624-O'84 December 31, 1992 􀀭􀁾􀁲􀀮􀀠Robert Wuilderlich
Barton·Aschman Associates, Inc. 5485 Beltline Road Suite 199 Dallas, Tens 75240 Dear Mr. Wunderlich: Enclosed for your review and information is a summary of charges that are associated
with an update to the Addison Airport Tunnel Study Wilbur Smith Associates (WSA)conducted earlier this year for the Texas Turnpike Authority ('ITA). You WIll find the summary addresses
costs for the modeling efforts and other ancillarv items required for the Arapaho Road Extension Project, • You will recall that your 􀀧􀁰􀁨􀁯􀁮􀁾􀀠discussions with John Smolley concerned
the addition of the Arapaho Road ExtensIon to the modellng efforts for the Addison AirportTunnel. Specifically WSA's earlier reEort did not have as part of the programmedhighway improvements,
the addition of the Extension to Arapaho Road. We have reviewed tile files on this project and have determined that the addition qf the Arapaho Road Extension to the modeling effort
would reqUire some reworking to the model in order to bring it up to a necessary level for assignment procedure. We estimate that the total fee to model this project would be $"8,456.
Please note that some $900 of this total fee is absorbed In the cost of a trip to Dallas to discuss the results of the effort once it is completed. This can obviously be removed from
the, study costs should you decide that the results could be presented to you by letter report and discussed by telephone. Tn any case, please review the attached summary 􀁯􂂬􀁣􀁾􀁴􀁳􀀭􀁡􀁭􀁈􀁥􀁾􀀧􀀱
􀀮􀁜􀁓􀀬􀁫􀀭􀁮􀁑􀁷􀀬􀁷􀁨􀁥􀀭􀁴􀁐􀀬􀁊􀀡􀀺􀀺􀀭􀁹􀁯􀁵􀁬􀀱􀁬􀁩􀀮􀁳􀁨􀀧􀀺􀁬􀁬􀀺􀁬􀁊􀁮􀁡􀁫􀁥􀀮􀁡􀁮􀁹􀀠􀁓􀀡􀁬􀁧􀁧􀀮􀁾􀀬􀁴􀁥􀁤􀀠􀁣􀁨􀁡􀁮􀁳􀁥􀀬􀁾􀀮􀀠You should also be made aware of the ITA's
concurrence in this assignment. Jim GriffIn has been aaprised of the level of effort involved in this analysis and is supportive 9f WSA's, accepting tne assignment. Assuming therefore,
􀁴􀁾􀁡􀁴􀀠you are interested In pursuing tills effort, we would need to make certam that all information proVided to us concerning the Arapaho Road Extension would be available in a
timely manner. Once that Information is received we would need apprOximately one month to perform the work efforts regarding this project. If this IS acceptablethiS document can then
SClrve as a contract by signing In the appropriate space... , .. provided. ALSANY, NV • ALLIANCE. OH • CAlnO, eGYPT • 􀁃􀁈􀁁􀁾􀁌􀁥􀁳􀁲􀁏􀁎􀀬􀀠so •COLUMBIA, SC • 􀁣􀁏􀁌􀁾􀁍􀁥􀁵􀁳􀀬􀀠OH
• DES MOINES, lA • FALLS 􀁃􀁈􀁕􀁾􀁃􀁈􀀮􀀠VA HONG KONG. HOUSTON, iX • KNOXVILLE, TN • UlXlNGTON. 'tY • LONDON, ENGI.AND • LOS ANGELI,S, CA • MIAMI, FL • 􀁎􀁾􀁥􀀬􀀺􀁾􀀺􀀮􀀺􀀢􀀬􀁾􀀠NEW
HAVEN, CT • OAK.AND. CA • ORLANDO. Fl • PITTSBURGH. r>A • PORTSMOUTH, NH • PROVIDENCI;, "\ • 􀁒􀁁􀁜􀀮􀀬􀀬􀀬􀀬􀁾􀀬􀀠";::,., 􀁯􀀬􀁾􀁵􀀬U'",,,, ,,. • 􀀧􀀧􀀧􀀧􀀮􀀧􀀧􀀧􀀧􀀧􀀧􀁾􀀠('A. 􀁒􀁾􀁓􀀬􀁬􀁛E.ll
• SAN FRANCISCO, CA' SAN JOS;, CA. SINGAPORE. 􀁔􀁏􀁾􀁏􀁎􀁔􀁏􀀬CANADA. NASHINGl'ON,O
v UEC-31-92 THU 16 ja 􀁗􀁉􀁾􀁂􀁕􀁒􀀠SMITH ASSOUIATES P .. 03 WILBUR SMITH ASSOCIATES Mr. Robert WunderUch December 31, 1992 Page Two We look forward to the possibility of working with
you on this project and would be 􀁰􀁬􀁥􀁡􀁾􀁥􀁤􀀠to answer any 􀁱􀁵􀁾􀁳􀁴􀁬􀁾􀁮􀁾􀀠􀁴􀁾􀁾􀁴􀁘􀁯􀁾􀁟􀁮􀀺􀁩􀁾􀁾􀁴􀁾􀁡􀁶􀁥􀀠􀁾􀁾􀁾􀁥􀀡􀁾􀁩􀁮􀁧􀀠any ?f the materialproVIded. Please da-not
nC51UILe V..l 􀀢􀀧􀁜􀁊􀁮􀁾..c. """u Sma!,,-, v. rn;e-·should 􀁪􀀧􀁏􀁉􀀮􀁴􀀭􀁲􀁾􀁵􀁭􀀻􀀡􀂷􀂷􀂷􀀠-......._.. additional clarification. Respectfully submitted, WILBUR SMlTIl ASSOCIATES
\.D .. 􀁾􀁣􀀠A•••'"L,. : ...... Norman H. Wuestefeld Executive Vice President SHW/mla/JS cc: James W. Griffin • ITA ACCEPTED BY CONTENT AND TERMS: NAME TITLE OROX"'lZATION SIGNATURE
DATE 
ExbibitA SUMM:ARY OF ESTIMATED STUDY COST Addison Airport Tunnel Update 1. Salaries and Wages CIASSIFICATrON 􀁈􀁏􀁕􀁒􀁾􀀠Senlor Officer 4 Officers 4 Associate EngineertPlannerlEconomist
16 Principal Engineer/Planner/Economist 16 Senior Engineer/Planner/ECOnomist 20 Technician 20 Technical Typist/Word Processor 8 Junior Analyst/Clerical S TOTAL 2. Fringe Benefits (49.28
Percent ofSalary Cost) 3. Overhead (106.05 Percent of Salary Cost) Subtotal 4. Fee (IS Percent) S. Direct ExpenseS" s SOO􀁾􀁬􀀠 􀂧􀁾􀁾􀁾􀁦􀁳􀁜􀁥􀁮􀁣􀁥􀀠100 e Reproduction and Publication
100 d Telephone, FAX and Office 50 e 􀁐􀁯􀁳􀁬􀁡􀁾􀁥􀀠and 􀁾􀁲􀁥􀁳􀁳􀀠50 f) Matenals and Supplies Jl Subtotal TOTAL COST ESTIMATED AYflRAGE !:OST $68.00 45.00 36.00 30.00 25.00 14.00
13.00 12.00 5272 180 576 480 SOO 280 104 􀁾􀀠$2,488 1,226 2,639 $6,.35.3 95.3 1.150 $8,456 
Barton·Aschman Associates, Inc. ;' 5485 Bell Line Road, Suite 199 Phone: (214) 991-1900 Dallas, Texas 75240 Fax: (214) 490·9261 USA Metro: 263-9138 MEMORANDUM To: Ron Whitehead Town
Manager From: Robert WUi'\?erlich Gary Jost 􀁾􀀠Date: December 18, 1992 Subject: Analysis of East/West Roadway Capacity in Addison Belt Line Road serves as the primary conduit of east/west
traffic flow north of the LBJ freeway (Figure 11. The combination of continuity from 1-35E on the west to US 75 on the east and the concentration of employment and residential Centers
along its route and an interchange with the Dallas North Tollway (DNTI, have resulted in a heavily travelled corridor with significant congestion during the peak hour. Currently, Belt
Line' Road carries approximately 37,783 vehicles per day just west of the DNT. Travel demand estimates project that congestion is to continue and worsen. Very little opportunity exists
to expand Belt Line Road due to adjacent property impacts and aesthetic considerations. Therefore, Therefore, it is essential that alternate routes be developed to relieve Belt Line
Road. POSSIBLE RELIEVER ROUTES Between Belt Line and Spring Valley, opportunities to provide relief are limited due to the presence of residential neighborhoods. Therefore, attention
has focused on the corridor north of Belt Line Road where a connection of Keller Springs and an extension of Arapaho Road are the most likely candidates for relieving Belt Line Road
(see figure 21. KELLER SPRINGS Keller Springs Road currently extends to the east and west from Addison Airport. Keller Springs extends from the Airport past Preston Road to Campbell
Road on the east side of the Airport. On the west, the road continues through Carrollton to 1-35E. Tunnelling under the Airport has been identified as the only feasible way to connect
the eastern and western sections of Keller Springs while maintaining Airport operations. Because of the substantial cost of such a project, funding is proposed through tolls. A two-lane
(one lane in each direction) tunnel with a $.75 toll is under consideration at this time. 
----Ron Whitehead Memo December 17, 1992 Page 2 ARAPAHO ROAD Arapaho Road is continuous from the Dallas North Tollway to US 75 west of the tollway, Arapaho intersects with Spectrum,
at an all-way stop right angle intersection. Arapaho then continues west to Addison Road. An alignment has been proposed which would extend Arapaho west from the DNT to Marsh Lane. PROJECT
TRAFFIC ANALYSIS As part of the Addison Transportation Plan project, the NCTCOG modeled several alternative roadway networks. One of the purposes of this effort was to explore the interaction
between the two alternative roadways and their ability to relieve Selt Line Road. Representative volumes are shown for this alternative model in Table 1. < '.:. 7.',Table 1 COMPARISON
OF VOLUMES JUSTWESTOF ADDISON ROAD YEAR 2010 No Keller Springs or Arapaho Keller Springs Free.4'Lane . Facility; No Arapaho 2 -Lane Keller Springs' Tollroad; No . Arapaho . 2 Lane Keller
Springs Tollroad; .. Arapaho Extended . ! to Marsh 113,000 Trinity Mills 17,000 SH 190 ! ! Keller Springs • --Lindburg 15,000 Arapaho Selt Line 61.000 TOTAL 254,000 113,000 19,000 30,000
10,000 56,000 273,000 114,000 112,000 20,000 18,000 16,000 16,000 13,000 1,000 ! --40,000 II 58,000 49,000 267,000 267,000 Without either of the alternative routes, Selt Line Road is
projected to have a demand of 61,000 vehicles per day. When the Keller Springs tunnel connection is modeled as a fourlane, free-access roadway, the volume of Selt Line Road is reduced
by about 5,000 vehicles, and the resulting volume on Keller Springs is 30,000 vehicles per day. When access to Keller Springs is restricted by charging a toll and reducing the width
to two lanes, the volumes on Keller Springs drops to 16,000 and the volume on Belt Line Road is reduced by only 3,000 vehicles. I 
Ron Whitehead Memo December 17. 1992 Page 3 When Arapaho is added between the North Tollway and Marsh. the volumes on Keller Springs toll tunnel are not affected. but volumes on Belt
Line Road are reduced by 12.000 vehicles per day to 49.000 vehicles per day. The daily traffic volume on Arapaho is projected to be 40.000 under these conditions. SUMMARY It is apparent
from the projected volumes that the Keller Springs toll tunnel and the Arapaho Road extension generally serve different travel needs and projected volumes on. Keller Springs are not
diminished when Arapaho is extended. The projected traffic volumes also support the need for all three facilities (Arapaho Road. Keller Springs Toll Tunnel. and SH 1901 to meet future
east-west travel demand. Each facility meets a specific need for travel in the area. Arapaho serves as a relief facility for Belt Line Road and provides a continuous circulation route
for adjacent land uses. The proposed Keller Springs Toll Tunnel chiefly links areas west of the Airport Airport to the Dallas North Tollway. Land uses within Addison are generally not
served directly although the toll tunnel could be used to access areas within Addison. It does not appear that even a four-lane. free Keller Springs connection would relieve Belt Line
Road. On the other hand. the Arapaho extension does carry traffic that could otherwise travel on Belt Line. but does not attract trips that would use Keller Springs. An analysis of the
intersections of Midway Road at Keller Springs and Addison Road at Keller Springs will be sent under separate cover. These intersections support the toll tunnel and will be important
to the success of the toll tunnel. 
m x Iii 􀁾􀀠G) :II 0 >" :;; >-< 8 z 􀁾􀀠c:. ." :II 13>.... c: :00 m 0 z 􀁾􀀠; 􀀭􀁚􀀭􀀺􀁚􀁩􀁾􀀧􀀽􀀽􀀽􀁟􀂭•" ' .. uQ\u.o 9\0 <•if 􀁾􀀠Webb Chlt* < 'if < f 4 􀁾􀀠􀁾•, '0, 􀀬􀁾• ",,0 􀁾􀀠.'"•
•• % IV "-: 0•if• <•=• » " -J,"oy Ln, 􀁾􀀠" 􀁾􀀠• • f 􀁾􀀠Kelly ell/O• Il0 •m• " = • " 􀁾􀀠,"• j"•". Men!) Ln. .. HII1Ct•• R., 􀁾􀀠􀁾􀀠• "•c • •.. <I 􀁾􀀠• " 􀁾􀀠"'" 􀁾Colt Rd. I 
:;--Clt)' Litnlt.-, Sojourn Ot. ..• •••!.. ? •1!. i·• o ." iiic: '" "'􀁾􀀠• » JJ JJ o rr... o z A, II 0 It\d. 'l,lndberg Of. 1,.-" lIRI! d . [,; > Q 􀁾.. .g '»􀀬􀁾􀀠􀁾􀀠. K.lh.r Drlnfjll
AI(tUn PIr • .,. , 􀁉􀁾􀀠􀀮􀁾•• Mlld,.d 􀁾􀀠Rd. o »0 0 0 '" m ."... C F! "0 >0 :< >-< 0 0 z.., Gl c 􀁾􀀠" [QJ is '" 0 » r-r» (J) rr» (J) 
􀁐􀁅􀁃􀀭􀁚􀁾􀀭􀀹􀁾􀀠THU 􀁾􀀶􀀺􀀲􀀹􀀠WILBUR SMXTH ASSOCXATES P.02 WILBUR SMITH ASSOCIATES 􀁅􀁎􀁇􀁉􀁎􀁅􀁅􀁾􀀠• ECONOMISTS. PLANNERS I35COLlEGESmm • p.O.aO)(9412 • NSW HAVliN, CTOO534 •
(20!) 86S02191 • 􀁆􀁁􀁬􀁩􀀨􀀲􀀰􀀳􀀩􀀶􀀲􀁾􀀮􀁯􀁾􀀠December 31, 1992 ·'NIt. Robert Wuilderlich Barton·Aschman Associates, Inc. 5485 BeltUne Road Suite 199 Dallas, Texas 75240 Dear Mr.
Wunderlich: Enclosed for your review and information is 11 summary_ of charges that are associated with an update to the Addison AirpOri Tunnel Study Wilbur Smith Associates (WSA)conducted
earlier this year for the Texas Turnpike Authority (ITA). You will find the summary addresses cOSts for the modeling efforts and other ancillary items required for the Arapaho Road Extension
Project, You will recall that vour"phone discussions with John Smolley concerned the addition of the Arapaho Road Extemion to the modeling efforts for the Addison AirportTunnel. Specifically
WSA's earlier re.eort did not have as pari of the programmedhighway improvements, the addition of the Extension to Arapaho Road. We have reviewed the flies on this project and have determined
that the addition of the Arapaho Road Extension to the modeling effori would require some reworking to the model in order to bring it up to II necesslU)' level for assignment procedure.
We estimate that the total fee to model this project would be $8,4S6. Please note that some $900 of this lotal fee is absorbed in the cost of a trip to Dallas to discuss the results
of the cffori once it is completed. This can obviously be removed from the study costs should you decide that the results could be presented to you byletter repori and discussed by telephone.
Tn any case, please review the attached summary o!coots-andlet·\\S·lw.cw.wheWl=.you)l.li..sh.1O.mm.any 􀁳􀁜􀁬􀁧􀁧􀀮􀁾􀁴􀁥􀁤􀀠􀁣􀁨􀁡􀁮􀁧􀁥􀀮􀁾􀀬􀀠You should also be made aware of the
ITA's concurrence in this assigtlment. Jim Griffin has been ap'prised of the level of effort involved in this analysis and is supportive of WSA s_accepting the assignment. Assuming therefore,
Ihat you are interested in pursuing this effort, we would need to make certain that all information provided to us concerning the Arapaho Road Extension would be available in a timely
manner. Once that information is received we would need approximately one month to perform the work efforts regarding this project. If this IS acceptablethis document can then serve
as a contract by signing in the 􀁡􀁰􀁰􀁲􀁯􀁰􀁲􀁩􀁾􀁴􀁥􀀠space_._... provided. ALBANY. NY. ALLIANCE. Or! • CAIRO. EGYPI • CHARLeSTON. SC • COLUMBIA. SC • COU.;M9US. Or! • DES MOINES.
IA • FALLS 􀁃􀁈􀁕􀁾􀁃􀁈􀀮􀀠VA HONG KONG. HOUSTON. T)( • KNOXVII.I.E. TN • LEXINGTON, 'IY • LONDON, ENIPI.AND • LOS ANGeLES. CA • MIAMI, fL • 􀁎􀁾􀁾􀁁􀀮􀁈􀀧􀀠􀁾􀀠NEWHAVEN. CT • OAKLAND. CA. ORLANDO, R • PIlTSaURGH.OI\ • PORTSMOUTH. NH • PROVIDENCe. Iii, • 􀁒􀀢􀀧􀀮􀀬􀀮􀁾􀀢􀀬􀁾􀀮􀀭􀁎􀀺􀀺􀀺􀀭􀂷􀂷•. 􀁾... 􀀬􀁾•.􀁾􀀠." . ""<""'''' 1'" • 􀁾􀀢􀁾􀀽􀀬􀀬􀀠<
" d'ANmANCiSCo.CA tSANJOSl:. CA. SlNGAI'ORE. TORONTO. CANADA • WASHI,IG,O:ol. Dv 
DEC-31-9Z THU 16:.e WILBUR SMITH ASSOCIATES P.03 WILBUR SMITH ASSOCIATES Mr. Roben Wunderlich December 31, 1992 Page Two We look forward to the possibility of working with you on this
project and would be pleased to answer any questions that you might have concerning any of the material provided. Please dO'11oi 􀁨􀁴􀀻􀁾􀁩􀁩􀁡􀁩􀁥􀀠to contact John Smolley or me--slloold-yGIt-re'lui
re··· ........_... . additional. clarification. Respectfully submitted, WILBUR SMl'm ASSOCIATES Norman H. Wuestefeld Executive Vice President 􀁾􀁈􀁗􀀯􀁭􀁬􀁡􀀯􀁊􀁓􀀠cc: James W. Griffin
-TTA ACCEPTED BY CONTENT AND TERMS: NAME TITLE ORGAt'llZATION SIGNATURE DATE 
DEC-31.-92 THU 16:3£'1 WXLBU"to< 􀀧􀁢􀁪􀁍􀁾􀁉􀁈􀀠􀁬􀀻􀀮􀀺􀀺􀁮􀀽􀀢􀂷􀁓􀁉􀀮􀀮􀀱􀁃􀀧􀀢􀁾􀂷􀁡􀁬􀀴􀁉􀂷􀁬􀂣􀁓􀀭􀀭􀀭􀂷􀀭􀁐􀁟􀀭􀀱􀀮􀀺􀀺􀀡􀀴􀀠Exhibit A SUMMARY OF ESTIMATED STUDY COST Addison
Airport Tunnel Update 1. Salaries and Wages CLASSIFICATION HOURS AVERAGJ; ESTIMATED COST Senior Officer Officers Associate Engineer/PlannerlEconomist Principal Engineer/Planner/Economist
Senior Engineer/Planner/Economist Technician Technical Typlst/Word Processor Junior Analyst/Clerical 4 4 16 Hi 20 20 8 8 $68.00 4S.00 36.00 30.00 25.00 14.00 13.00 12.00 TOTAL 2. Fringe
Benefits (49.28 Percent ofSalary Cost) 3. Overhead (106.05 Percent of Salary Cost) Subtotal 4. Fee (lS Percent) 5. Direct Expenses-' a Travel b Subsistence c ReprodUction and PUblication
d Telephone, FAX and Office e 􀁐􀁯􀁳􀁴􀁡􀁾􀁥􀀠and !:;press• MaterIals and Supplies S 800 100 100 50 50 J Subtotal TOTAL COST 5272 180 516 480 500 280 104 􀁾􀀠$2,488 1,226 2.639 $6,353
953 1,150 S8,456 
Barton·Aschman Associates, Inc. 5485 Belt Line Road, Suite 199 Phone: (214) 991-1900 DaUas. Texas 75240 Fax: (214) 490-9261 USA Metro: 263-9138 MEMORANDUM To: Ron Whitehead Town Manager
From: Robert 􀁗􀁵􀁾􀁥􀁲􀁬􀁩􀁣􀁨􀀠Gary Jost 􀁾􀀠Date: December 18,1992 Subject: Analysis of East/West Roadway Capacity in Addison Belt Line Road serves as the primary conduit of east/west
traffic flow north of the LBJ freeway (Figure 1). The combination of continuity from 1-35E on the west to US 75 on the east and the concentration of employment and residential centers
along its route and an interchange with the Dallas North Tollway (DNT), have resulted in a heavily travelled corridor with significant congestion during the peak hour. Currently, Belt
Line' Road carries approximately 37,783 vehicles per day just west of the DNT. Travel demand estimates project that congestion is to continue and worsen. Very little opportunity exists
to expand Belt Line Road due to adjacent property impacts and aesthetic considerations. Therefore, it is essential that alternate routes be developed to relieve Belt Line Road. POSSIBLE
RELIEVER ROUTES Between Belt Line and Spring Valley, opportunities to provide relief are limited due to the presence of residential neighborhoods. Therefore, attention has focused on
the corridor north of Belt Line Road where a connection of Keller Springs and an extension of Arapaho Road are the most likely candidates for relieving Belt Line Road (see figure 2).
KELLER SPRINGS Keller Springs Road currently extends to the east and west from Addison Airport. Keller Springs extends from the Airport past Preston Road to Campbell Road on the east
side of the Airport. On the west, the road continues through Carrollton to 1-35E. Tunnelling under the Airport has been identified as the only feasible way to connect the eastern and
western sections of Keller Springs while maintaining Airport operations. Because of the substantial cost of such a project. funding is proposed through tolls. A two-lane (one lane in
each direction) tunnel with a $.75 toll is under consideration at this time. 
Ron Whitehead Memo December 17, 1992 Page 2 ARAPAHO ROAD Arapaho Road is continuous from the Dallas North Tollway to US 75 west of the tollway, Arapaho intersects with Spectrum, at an
all-way stop right angle intersection. Arapaho then continues west to Addison Road. An alignment has been proposed which would extend Arapaho west from the DNT to Marsh Lane. PROJECT
TRAFFIC ANALYSIS As part of the Addison Transportation Plan project, the NCTCOG modeled several alternative roadway networks. One of the purposes of this effort was to explore the interaction
between the two alternative roadways and their ability to relieve Belt Line Road. Representative volumes are shown for this alternative model in Table 1. .. Table 1< .... COMPARISON
YEAR 2010 . OF 􀁖􀁏􀁌􀁕􀁍􀁅􀁾􀁾􀀰􀁳􀀻􀁾􀁅􀁾􀀻􀀶􀁾􀁾􀁢􀁢􀁬􀁾􀀻􀁾􀁾􀁾􀀨􀀩􀁾􀁄􀀧..... .. .... , No Keller Springs 6r . ... Arapaho . Keller Springs Free4'Laile' . Facility; No Arapaho ..
2 -Lane Keller Springs . Tollroad; No. ·Arapaho·.·. 2 .Lane· Keller, . 'Springs, T6I1road;. •Arapaho Extended . ..... '. to Marsii .. SH 190 Trinity Mills Keller Springs Lindburg Arapaho
Belt Line 113,000 17,000 .15,000 .61,000 113,000 19,000 30,000 10,000 .56,000 114,000 20,000 16,000 13,000 .58,000 1i 2,000 18,000 16,000 1,000 40,000 49,000 TOTAL 254,000 273,000 267,000
267,000 Without either of the alternative routes, Belt Line Road is projected to have a demand of 61,000 vehicles per day. When the Keller Springs tunnel connection is modeled as a fourlane,
free-access roadway, the volume of Belt Line Road is reduced by about 5,000 vehicles, and the resulting volume on Keller Springs is 30,000 vehicles per day. When access to Keller Springs
is restricted by charging a toll and reducing the width to two lanes, the volumes on Keller Springs drops to 16,000 and the volume on Belt Line Road is reduced by only 3,000 vehicles.

Ron Whitehead Memo December 17, 1992 Page 3 When Arapaho is added between the North Tollway and Marsh, the volumes on KeUer Springs toll tunnel are not affected, but volumes on Belt
Line Road are reduced by 12.000 vehicles per day to 49,000 vehicles per day. The daily traffic volume on Arapaho is projected to be 40,000 under these conditions. SUMMARY It is apparent
from the projected volumes that the Keller Springs toll tunnel and the Arapaho Road extension generally serve different travel needs and projected volumes on. KeUer Springs are not diminished
when Arapaho is extended. The projected traffic volumes also support the need for all three facilities (Arapaho Road, KeUer Springs Toll Tunnel, and SH 190) to meet future east-west
travel demand. Each facility meets aspecific need for travel in the area. Arapaho serves as a relief facility for Belt Line Road and provides a continuous circulation route for adjacent
land uses. The proposed Keller Springs Toll Tunnel chiefly links areas west of the Airport to the Dallas North Tollway. Land uses within Addison are generally not served directly although
the toll tunnel could be used to access areas within Addison. It does not appear that even a four-lane, free Keller Springs connection would relieve Belt Line Road. On the other hand,
the Arapaho extension does carry traffic that could otherwise travel on Belt Line, but does not attract trips that would use Keller Springs. An analysis of the intersections of Midway
Road at Keller Springs and Addison Road at Keller Springs will be sent under separate cover. These intersections support the toll tunnel and will be important to the success of the toll
tunnel. 
Colt Rd. 0" _ -="-,,::::==___ 􀁾􀀠= ," 􀁾􀀠• KlIIIlly 91'14. • Webb Ctla.DII Rd, m :: 􀁾􀀠•" 􀁾􀀮􀀬􀀠􀁾􀀠•,.-'" ..•• ",. % 1l0\\;l.Q ",,0 <'., f••• Jo._y Lit. 􀁾•" • 􀁾􀀠= <•: 􀁾􀀠<;;•c
? v MuahLI\"0, HUlet.. Rd, .. 􀁾􀀠n D 􀁾􀀠• < ;. 0 .. S-f1 􀁾􀀠" ,. "• •!.. ,." " • ,." m Xa; .... Z Ci> :u 0 0 " :; "-< 8 z :!l c Ci> ..:u is>-C;.... :0a m @Z I 
DALLAS Q »0-••••-:.;: 􀁾􀁾􀀠􀁩􀁾􀀠!Il__ "Iwu" L_ 􀁾􀀠DALLAS ,; ¢ ·•• ;;; : "• ; 􀁌􀀮􀁤􀁡􀀮􀀢􀀬􀁾􀁾􀁾􀁕􀀡􀀮􀁦􀀺􀀠.. ! Gol Ouofum Dr.'/􀁾•. •-􀁾􀀠􀁾􀀠􀁕􀁾􀀠􀀮􀁾􀁏􀁏􀁜􀀢􀀠AddlU'n 􀁾􀁤􀀮􀀠""¢
•<•• 􀁾• tn.rk 􀁢􀁬􀀢􀁣􀀡􀀺􀀮􀀮􀀭􀀭􀁾􀀴􀀧􀀠! ;; Q .. : r------l ,, OUlia R.f:I. ."Q Ctty llml,. FARMERS BRANCH ·-----1CARROLLTON " '.# • .,.... ' 􀀭􀁾􀀽􀀺􀀻􀀺􀀺􀀧􀀧􀀧􀀭􀁚􀁬􀀺􀂭"<;l..,
I' Mot to Sea'. 0" ,, 􀁾􀀮􀀠FIIJURE 2 CONCEPTUAL ROADWAY CONFIGUflATION 􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀀠

GINN, INC. CONSULTING ENGINEERS December 9, 1985 Honorable Mayor Jerry Redding & Council Post Office Box 144 Addison, Texas 75001 Dear Mayor Redding: Ginn, Inc., in association with
Barton-Aschman Associates, Inc. and Howard Needles Tammen & Bergendoff is pleased to present our report for the Addison Airport-Keller Springs Underpass. The report addresses two major
elements: a traffic analysis of future traffic volumes surrounding the Addison Airport;and a feasibility study which evaluates several alignmentsand tunnel designs. The findings and
recommendations are summarized in the Executive Summary. We appreciate the opportunity to be of continued service to the Town of Addison and look forward to working with the Citystaff
on this important project. Sincerely, 􀀱􀁦􀁾􀀯􀀨H. Wayne Ginn, P.E. RH/HWG/sr Enclosure 16135 Preston Road. Suire 106 • Dallas. Texas 75248. Phone 214/386-6611 
ADDISON AIRPORT -KELLER SPRINGS UNDERPASS STUDY Table of Contents I. Executive Summary II. Barton-Aschman Report III. Howard Needles Tammen & Bergendoff Report 
EXECUTIVE SUMMARY The Executive Summary presents a synopsis of the preliminary feasibility studies for the Keller Springs Underpass prepared for the Town of Addison by Ginn, Inc., in
association with Barton-Aschman Associates, Inc. and Howard Needles Tammen & Bergendoff. The studies investigated future traffic volumes, design schemes and associates preliminary costs
to determine if the Keller Springs Underpass warranted further study. A traffic study was conducted to determine the volume of traffic which would use the proposed Keller Springs Underpass
upon build-out of Addison, Farmers Branch, Carrollton, Plano, and the North Dallas area. The Cities of Dallas and Carrollton plan for Keller Springs Road to be a major thoroughfare consisting
of six-lane divided roadway. According to the projected traffic volumes along Keller Springs, the underpass needs to carry 40,000 vehicles per day. This volume of traffic requires a
six-lane divided roadway. Consequently, without the underpass to provide continuity to the the North Dallas area thoroughfare plan, east/west roads such as Trinity Mills and Belt Line
Road will have to carry the additional east/west traffic. The second part of study investigated various alignments for the Keller Springs Underpass and developed preliminary project
costs for the alignment. These alignments are 1 
[$ E , I " DO : o[ Figure 2 2 
presented in Figure 2. Items such as airport runway clearance, access to adjacent properties, and tunnel construction were considered in evaluating the various alternatives. Based on
these items, Alignment A was recommended for the underpass. Upon establishment of an alignment, several tunnel methods were evaluated. The tunnel methods considered for traversing the
airport were cut-and-cover, shallow tunneling, and deep tunneling. A cut-and-cover method of construction would suspend airport operations for extended periods of time. Therefore, this
method was not given further consideration. A shallow tunnel with approximately 10 feet of cover has less approach 􀁲􀁯􀁡􀁤􀁜􀁾􀁡􀁹􀀠and retaining walls. However, this asset is offset
by the added structural costs associated with a shallow tunnel system. The deep tunnel method with approximately 30 feet of cover would provide natural structural support and thus decrease
the cost of tunnel construction. The deep tunnel approach allows for the construction of 2 􀁾􀀠two lane tunnels with the possibility of 2 -three lane tunnels. The shallow tunnel would
only allow for tunnels to be constructed in multiples of two lanes. Figures 4 and 5 present typical tunnel sections for the two-lane and three-lane roadways. Tunnel construction would
require a ventilation system to exhaust CO and C02 emitted from the vehicles; a drainage system to handle unexpected spills of water or fluids from tank trucks, rainwater and washdown
water; a lighting system 3 
12'PIAMeTE.e f 􀁔􀁖􀁎􀁎􀁾􀁌􀀠ROADWAY' '----+-+-.4IR RJRT tJPeUING lO" SUB-BASe REIIJFORCEP COAICRETE BASfi .i" 81Tl/MIJ/O(I$ St«'FACI? 2' CAST-1M-PlACe CONCReTe FINAL. I.IJlII./G CUlf8
[J1!A1'" ?Ji!! API'lICAl';(.e 11:) I!CnI S/lAI.LCW IlAiI) J)EEP 'f'IJIIN€I-At:(elelllmrff!$ HNTB VllPI!RPRAIN Figure 4 TYPICAL 2 -LANE TUNNEL SECTION 4 
.. 18" PIAMffEl? t:ROOF SUPPORT'---11 -'1:-ycNTll..ArlOAl SPAce ----.. -All? PORI (peAliNG 161..6" MIAlI14UM WIIICI../! aeARANCe.) FLOReSCeAIT l.IGHTIAlG I {Oil SUS-BASE \... 10" Rl!lNFORCeD
COAIC. 12" UAlDI!RPRAIN 􀁾BIT1IMIAIOVS 􀁓􀁾􀁦􀁩􀀴􀁃􀁉􀀡􀀠Figure 5 TYPICAL 3 -LANE TUNNEL SECTION L-􀁾􀀠rt./AlAlEL Ii f 􀁾􀁏􀁁􀁏􀁗􀀴􀁙􀀠I I (II UlJ/)cROI?AIAI HNTB 􀁈􀁃􀁉􀁜􀀮􀁾􀀬􀀽􀁲􀁲􀁮􀀠􀁾a
_ ••hIDCIPF_ 2'-0" CASr·lIo/-Pi..4ct! COAleRffE FIAIAL t..IJJIJ./G -("vt<;o DIMIAI 􀁾􀀨...--IIPPLICItBi..E -ro filE DEEP -rWNEl./lcl1!.Il.AlJ/1"7IfE (JAIL'! 
to provide adequate light for driving and fire hose connections every 200 feet along the tunnel. These systems would be investigated further during the design phase of the project. preliminary
construction costs were prepared for the various tunneling alternatives for Alignment A. Estimates were prepared for 2 -two lane tunnels and for 2 -three lane tunnels for the deep tunnel
alternative under the Addison Airport. Estimates were prepared only for 2 -two lane tunnels for the shallow tunnel alternative. The costs of these are as follows: Shallow tunnel 2 -two
lane $30,000,000 Deep tunnel 2 -two lane $28,800,000 Deep tunnel 2 -three lane $40,200,000 Recommendations: It is recommended that more extensive studies be conducted in the following
major areas: * Subsurface Explorations -It is recommended that at least six (6) soil borings and their associated soil analyses be developed in an effort to more accurately develop soil/rock
characteristics and profiles. These soils analyses are also intended to provide data to further assess the feasibility and costs associated with shallow tunneling. * Obtain Updated Mapping
-The recent construction of an FBO abutting the taxiway in the vicinity of the 6 
project and also recent construction near the terminals of the project necessitate the requirement for updated mapping. * Refinement of Geometry and Capital Costs -Whereas the initial
study considered several alignments, the selected alignment will be further refined to confirm its viability. Develop Operations and Naintenance 􀀨􀁏􀀦􀁾􀁉􀀩􀀠Costs -O&M* costs will
be developed relying on experience from tunnel projects in other parts of the country as they relate to the subject project. * Develop Right-of-Way Costs -It is recommended that development
of right-of-way costs through the services of an independent appraiser be obtained. This would include costs of lease buy-outs and relocation. * Develop Preliminary Cost Estimates -Preliminary
construction cost estimates will be prepared based on estimates of the quantities of major construction items and application of the approximate current unit prices to the preliminary
quantities. Develop Operational Plan -An operational plan* illustrating procedures during during emergencies will be developed. * Coordinate these findings with FAA and other appropriate
governmental agencies. * Develop a source of potential funding. 7 
DRAFT REPORT KELLER SPRINGS UNDERPASS AT ADDISON AIRPORT FEASIBILITY STUDY -TRAFFIC PROJECTION ADDISON, TEXAS BARTON-ASCHMAN ASSOCIATES, INC. August, 1985 
The purpose of this report is to present the results of a study conducted for the City of Addison and Ginn, Inc. concerning the potential extension of Keller Sprin;ls Boad un:ler h'Jdison
Ai:rport. Pl:ojected traffic volumes for the proposed extension are presented in this report toqether with an evaluation of the impact of the extension on traffic volumes alorr;r Belt
Line Road ani Trinity Mills. REUm SPR:DCS BlI\D Keller SprinJs Boad is an east/west thorcu::Jhfare sloteet that currently is const:J:ucted from campbell Boad to AMison Road on the eastside
of JIdrlison Airport. west of Addison Airport, Keller Sprinqs Road will eventually connect with Whitlock Road to prc<Tide a direct link with Interstate Highway 35E (m 35E). west of m
35E, Whitlock becomes Sandy I.ake Road ani e.xt:e.r:ds into the city of COppell. '!he City of Dallas has recently upgraded Keller SprinJs Road to major thoroughfare sta'bls as a six-lane
divided roadway lletween Preston Boad ani the Dallas North Tollway. west of Midway Road, in in the City of carrollton, Keller SprinJs Road is desiqnated as a six-lane divided 􀁾􀁡􀁲􀁥􀀮􀀠Projected
traffic volumes for Keller Sprinqs Road and its proposed extension un::l:er JIdrlison Airport are shown in Figure 1. Traffic volumes for other major thoroughfares in the vicinity of
the proposed Keller Sprinqs extension are also shown in Figure 1. !Ihese traffic volume projections were developed in conjun::::tion with the recent Parkway center study con::l.ucted
for the City of Dallas and reflect those volumes that are projected to occur upon build-out of the AMison, Fanners Branch, carrollton, Plano, ani North Dallas area. The projected traffic
volumes are projected to occur beyond the Year 2000. Keller Sprin;Js is projected to carry awrox;i:mately 40,000 vehicles per day, if it is constructed under the airport. As can l::!e.
seen in Fiqure 1, other parallel major thorcu::Jhfares (i.e. Belt Line Road ani Trinity Mills) are projected to have traffic volumes in excess of 40,000 vehicles per day 􀁡􀁬􀁯􀁾􀀠certain
sections of roadway. 
No 6ca'e KELLER SPRINGS Do "'0 􀁾􀁏ill: • Q ID i (') ADDISON AIRPORT o o o ,..... 42,400 o o o 46.500 BELT LINE RD. 0 0 0'. I/)..,. \ 0 0 0 " '? I/) (')... 54,500 0 0 0 (') I/) 52,000
LEGEND 40,000 -Traffic Volume in Vehicles Per Day FIGURE 1 PROJECTED TRAFFIC VOLUMES L-____􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀁾􀀠
The proposed extension of Keller Springs Road will have a positive iJnpact on projected traffic alcrq 'l'rinity Mills ani Belt Line :Road as well as certain sections of Preston :Road
due to the fact that it will provide an additional oontin:uous east/west thoroughfare between Central Expressway (U.S. 75) and m 35E. With the proposed extension of Keller Springs Road,
projected traffic volumes on Belt Line Read can :be eJq;lE!cted to :be reduced :bY as much as 5,000 vehicles per day. Likewise, projected volwnes along TrWty Mills can also :be reduced.
KWl'IAY SIZlNG Roadway capacity is a measure of a roadway'S ability to a=mmodate a volwne of traffic at an acceptable level of traffic operation. The wider the street, the higher the
traffic volu:me that can :be a=mmodated. Listed :below are the maximum traffic volumes that can :be accommodated for various sizes of roadways. Size of Roadway Traffic capacity (Vehicles
Per ]l;y) 4-Lane Undivided 22,000 4-Lane Divided 24,000 6-Iane Undivided 33,000 6-Iane Divided 42,000 Based on the projected traffic volwne of 40,000 vehicles per day, Keller Springs
Road needs to :be a six-lane thoroughfare. Based on the projected traffic volwnes for the extension of Keller Springs Road under Addison Airport, the following conclusions can :be reache:l..
1. Keller Springs Road needs to :be extended under Addison Airport to a=mmodate east/west traffic flow that is projected to = at total development of the Addison,INorth ]l;llas area.
2. Keller Springs :Road needs to :be ccnstructed as a six-lane thoroughfare street. 3. The extension of Keller Springs Road under the Addison Airport will provide an additional, mudl
needed, east/west thoroughfare ani should help relieve projected traffic on Belt Line :Road ani TrWty Mills. 
DRAFT REPORT KELLER SPRINGS UNDERPASS AT ADDISON AIRPORT FEASIBILITY STUDY ADDISON, TEXAS HOWARD NEEDLES TAMMEN &BERGENDOFF August, 1985 
KELLER SPRINGS UNDERPASS AT ADDISON AIRPORT FEASIBILITY STUDY TABLE OF CONTENTS Page 1.0 INTRODUCTION •••••••••••••••••••••••••••••••••••••••••••••••••• 1 2.0 PURPOSE AND SCOPE ••••••••.••.••.••.••••
••••••••••••••••••••••• 1 3.0 PROJECT DESCRIPTION ••••••••••.••••••••••••••••••.••••••••••••• 2 o Design Parameters .••••••••••••••••••••••••••••••••••••• 2 o Alternative Alignments
••••••••••••••••••••••••••••••••• 4 4.0 GEOLOGIC PARAMETERS OF ENGINEERING SIGNIFICANCE ••••••••••••••• 8 o Geology •••••••••••••••••••••••••••••••••••••••••••••••• 8 o Previous Geotechnical
Exploration •••••••••••••••••••••• 12 o Expected Ground Behavior ••••••••••••••••••••••••••••••• 14 Tunnel Excavation ••.•••••••••••••••••••••••.•••• 14 Ground Stability •••••••••••••••••••••••••••••
••• 14 -Groundwater Infiltration •••••••••••••••••••••••• 17 5.0 TUNNEL EXCAVATION AND INITIAL SUPPORT ••••••••••••••••••••••••• 17 o Excavation Alternatives ••••••••••••••••••••••••••••••••
17 o Initial Support and Surface Protection ••••••••••••••••• 18 o Groundwater Control •••••••••••••••••••••••••••••••••••• 20 6.0 FINAL SUPPORT AND LINING ••••••••••••••••••••••••••••••••••••••
21 7.0 SPECIAL CONSIDERATIONS ••••••.••••••••••••••••••••••••••••••••• 21 o Tunnel Ventilation ••••••••••••••••••••••••••••••••••••• 21 o Tunnel Drainage ••••••••••••••••••••••••••••••••••••••••
23 o Tunnel lighting •••••••••••••••••••••••••••••••••••••••• 24 o Wa 11 and Cei 1i ng Treatment ••••••••••••••••••••••••••••• 24 o Fire Fighting ••••••••••••••••••••••••••••••••••••••••••
25 8.0 CONSTRUCTION ESTIMATE ••••••••••••••••••••••••••••••••••••••••• 25 9.0 CONCLUSIONS AND RECOMMENDATIONS ••••••••••••••••••••••••••••••• 27 o Tunneling ••••••••••••••••••••••••••••••••••••••••••
•••• 27 o Recommendations •••••••••••••••••••••••••••••••••••••••• 28 10.0 REFERENCES ••••••••••.••••••••••••••••••••••••••••••••••••••••• 28 
1.0 INTRODUCTION Keller Springs Road is a major east-west traffic artery serving the City of Addison and the rapidly developing urban area of northern Dallas County, Texas. The roadway
is interrupted by the Addison Airport just south of the Dallas County 1 fne. Proposed improvements to Keller Springs Road would increase its capacity by connecting adjacent segments
through the airport property. Completion of Keller Springs Road through the airport would also serve to reduce congestion on parallel arterials such as Belt Line Road and Trinity Mills
Road. Tunneling is considered the only alternative to enable the proposed improvement to Keller Springs Road and maintain the airport as fully operational during construction. 2.0 PURPOSE
AND SCOPE The purpose of this study is to develop a recommended al ignment for the extension of Keller Springs Road and to develop project costs for that alignment. -It addresses items
such as airport runway clearance, access to adjacent properties. and construction costs and considerations with specific emphasis on tunnel construction. Although a cut-and-cover method
for traversi ng under the ai rport was considered and is addressed in this report, tunneling appears to be the only reasonable method of construction. The feasibility of any tunneling
project is ultimately dependent on the cost of the project. To adequately predict such costs, an assessment must be made as to the geologic conditions which may reasonably be encountered.
Geotechnical engineering assumptions lead to an appraisal of ground behavior, applicable construction alternatives, and a feasibility level cost est imate. Thi s report identifies and
1501 ates geologic and engineering parameters specific to the Addison, Texas area as they relate to tunnel construction. Recommendations for suitable tunnel geometries and excavation
and support methods are presented along with special concerns including tunnel ventilation, drainage, lighting, and fire protection. 1 
This report is organized as follows: Section 1.0 Introduction Section 2.0 Section 3.0 Section 4.0 Section 5.0 Section 6.0 Section 7.0 Section B.O Purpose and ScopeProject Description
Geologic Assumptions of Engineering Significance Tunnel Excavation and Initial SupportFinal Lining and Support Special Considerations Construction Estimate Section 9.0 Conclusions and
Recommendations Section 10.0 References It should be emphasized that no geotechnical exploration and testing program was conducted for this feasibility study. Conditions anticipated
were inferred from generally available geotechnical data including state geologic reports, project data from the nearby Dall as North Tollway extension, and a limited number of shallow
oorings taken at the airport site for construction of a sewer line. 3.0 PROJECT DESCRIPTION The Addison Airport is located as shown in Figure I, in the center of the Ci ty of Addi son
and just north of the city of Dallas. The ai rport is oounded on the south oy the St. Lout s-Southwest Rail road tracks, Dooley Road on the west, Sojourn Drive on the north, and Addison
Road on the east. The topography is an open. rolling plain with a maximum elevation different of approximately 15. feet. The airport facilities include the 7,000 foot long runway, several
taxiways, and numerous hangar ouildings. Airport facility usage is general aviation and corporate-type aircraft. Design Parameters Design parameters were estao1ished to provide the most
economical facility that would still serve the traffic demand. The following basic design parameters were used in this study: Des; gn Speed -35 mphMaximum Hori lonta 1 Curvature -500
feet Max imum Grade -6·% Runway Clearances -150 feet from r: runway -100 feet from r: taxiway 2 
OALl..AS co. liNe: ri---r-r---BELT PROPOSEO J08 sIre KELLER ROAD SPRINGS OALLAS NORTH TOLLWAY ,S mi., SCALE LOCATION MAP 1000' I I SCALE" Figure I SITE PLAN HNTB -3I>CJlw..., .... .......
􀀬􀀮􀀮􀀢􀁾􀁾􀁡􀁟􀀭NDDFF , __ 
) Other items such as right-of-way requirements, lane widths, turn lane widths, etc., are consistent with major thoroughfare design standards used in the City of Addison. Alternative
Alignments Alternative alignments were investigated as shown in Figure 2. Each alignment was evaluated based upon its total project cost, length of tunnel section, impact on adjacent
properties, and relative traffic service. The recommended alignment, (Alternate A), begins at the intersection of Midway Road and Keller Springs Road, extends easterly along Keller Springs
Road under the runway and taxiway, then curves to south and easterly between FBOs along the existing taxiway. The roadway would then extend ENE to Addison Road along an extension of
existing Keller Springs Road. The total length of the project would be 3,600 feet, including an BOO-foot tunnel section under the airport runway and taxiway. The al ignment requires
the relocation of some existing T-hangers. Access to existing facilities interrupted by the open cut section of the facility would be restored by bridging the open cut section through
conventional methods. Costs for this bridging is incl uded in the project cost summary presented later in this report. A 1"=100' plan depicting this alignment and its impact on existing
streets and airport facilities accompanies this report. Alternative Al ignment B, (Alt. B in Figure 2), would begin at the intersection of Midway Road and Keller Springs Road, extend
easterly along Keller Springs Road under the runway and taxiway to Glen Curtis Drive, then conti nue ENE along Gl en Curti s Dri ve to Addi son Road. Thi s alternati ve offers a sl ightly
lower tunnel ing cost then Alternate .A due to a more normal crossing of the runway and taxiway, and it would probably have a lesser impact on existing airport facilities. However, this
alignment would require Keller Springs Road through traffic to travel on Addison Road between existing Keller Springs and Glen Curtis Roads, negatively affecting the capacity of both
Keller Springs and Addison Roads. For this reason, together with the minimal cost savings over Alternate A, Alternate B is not recommended. 4 
Again, in an effort to minimize tunneling costs, a third alternate (Alternate C) was developed. This alternate would begin south of the 􀁬􀁮􀁾􀀠tersecti on of Midway Road and Ke11 er
Spri ngs Road, extend ENE and tunnel under the taxiway and runway. and continue ENE and terminate at the 􀁩􀁮􀁴􀁥􀁲􀁾􀀠section of Addison Road and Keller Springs Road. However, this
alignment would require the acquisition of at least one business between Dooley Road and Midway Road and an FBO along the taxiway. Similarly to Alternate B but on the west side of the
airport, it would offset the proposed and existing intersectionof Keller Springs Road and Midway Road, negatively impacting overall traffic capacity as compared to Alternate A. For these reasons, this alternate 1s not recommended. Upon sel ection
of Alternate A as the recommended al ignment, tunnellng schemes were developed for two alternates differing in depth to roadway grade. The deep tunnel alternative consists of approximately
3,000 feet of roadway of which approximately 800 feet would be in tunnel, (2 tunnels, each 800 feet long), with roadway grade approximately 60 feet below the runway. and 1,100 feet of
approach roadway on each side of the tunnel in retained open cut. The second alternative is a shallow tunnel with roadway grade approximately 40 feet below the runway and 670 feet of
approach roadway on each side of the tunnel in retained open cut (see Figure 3.) The approach roadways would be sloped at 􀀶􀁾􀀠grade. A cut-and-cover method of constructing that portion
of the project under the runway and taxiway has been explored. However, this method of construction requires the suspension of airport operations for extended periods of time. Also,
due to the substantial loading requirements of the members spanning the roadway. the cost savings when compared to tunneling are expected to be minima I. if at all. For these reasons.
the cut-andcover method has been eliminated from further consideration. Generally, highway tunnels constructed within the United States have been limited to two-lane size widths. Where
more traffiC capacity is required, multiple two-lane tunnels are constructed. However, for this feasibility 6 
< iI! 
study. both two-lane and three-lane tunnel sections are developed and are presented in Figures 4 and 5. The 􀁴􀁷􀁾􀁬􀁡􀁮􀁥􀀠tunnel section is applicable to both the shallow and deep
tunneling alternatives. The three-lane tunnel section is considered to be applicable only to the deep tunnel alternative for reasons related to geologic and construction considerations
which are discussed later in this report. The two-lane tunnel section is wide enough to provide a clear inside opening of 32 feet. adequate for two 13-foot wide lanes of traffic. a 4-foot
manway and curbs· or alternately two ll-foot roadways and a 6-foot shoul der (breakdown I ane) and curbs. The three-l ane tunnel section provides for three 13-foot wide traffic lanes
and two, 4-foot wal kway or alternately three, ll-foot wide traffic roadways and a 6-foot and 3-foot wide breakdown lane pI us curbs. Separation between adjacent tunnel s is approximately
18 feet for two 2-lane tunnels and 28 feet for two 3-1 ane tunnels at the tunnel portals as depicted by Figure 6. Entering approachways are in confonnance with the City of Addison's
Standard four and sixlane design roadway sections. 4.0 GEOLOGIC PARAMETERS OF ENGINEERING SIGNIFICANCE Geology The rocks in Da 11 as County are Upper Cretaceous in age. underl ai n unconformably
by Paleozoic Era strata (see Figure 7.) Around the City of Addison. the rock near the ground surface is the Austin Fonnation which has been described by Shul er, (1918): The Austin formation,
or Austin chalk, consists of a thick series, about 500 feet, of alternating beds of chalk and shaly I imestone and marls which have a bl ue color when saturated with underground water,
but which are cream colored or glaring white upon exposure to weatheri ng. Al though the fonnat ion is tenned the Austin chalk, in Dallas County only a few layers near the base are properly
tenned chalk. The lower division of the Austin fonnation is also characterized by an abundance of nodular, spherical, or cylindrical concretions of iron pyrites, "fool's gold", which
on weathering gives rise to streaks of rust stain down the chalk wall. 8 
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100' 􀀲􀁾􀀠2l.ANE 2-8 LAUE Figure 6 iYPICAL 7l/UIJEL. POI!T"AI. SECi/O", AUSTIN CHALK EAGLE FORD SHALES U In ::J WOODBINE SANDS 0 0 DENNISON BEDS wN <..) FORT W JRTH LIME::; I ur0 «
(J) .... PRESTON BEDS w w 􀁾􀀠a: GOODLAND LIMESTONE<..) PALUXY SANDS GLEN ROSE FORMA nON TRINITY SANDS PALEOZOIC ERA ! I After Shuler, 1918 FIGURE 7 GENERAL GEOLOGIC COLUMN FOR DALLAS
COUNTY MI:S\.'......a p ,. -􀀮􀀬􀀮􀀬􀀮􀀮􀁾a _"'__'...CO"OI_. -11
The middle division of about 250 feet has fewer massive layers and is characterized by thick, and often indurated shaly layers which show remarkable lamination, many layers to the inch.
In the uppermost division of the Austin formation, the proportion of shaly limestone is larger and the chalk layers are rare. The top of the rock is weathered to depths ranging from
0 to approximately 10 feet. the colors are predominantly blue and yellow. Occasionally sandy layers are found. The dip of the Austin chalk is gentle, varying from 40 to 100 feet per
mile, with an average dip of 50 to 60 feet. One of the most characteristic features of the chalk as it occurs in Dallas County is the small scaled faulting. The chalk has been broken
into innumerable. irregular blocks by fissure planes along which most often slight movements have taken place. The faulting may be barely perceptible, or as much as 2 or 3 feet at a
maximum. The faulting is normal. Horst and graben structures alternate in rapid succession. The blocks vary vary in size from 50 to 100 and more feet in length. The plane of faulting
varies from 40· to 80·, the larger number varying from 45' to 60·, The strike of the fault planes is extremely variable and has no preferred orientation. Two types of jointing are found
in the chalk: ordinary joint planes at right angles to the bedding planes, and particularly in the more massive beds, curved joint surfaces which look as if they were made by localized
pressure on small surfaces--such surfaces as would be made by a punch in a uniform mass. Previous Geotechnical Exploration Previous geotechnical exploration programs conducted for projects
near the airport site suggest a typical geologic profile for the area as detailed in Figure 8. At the surface. residual soils of inorganic to organic silts and clays are found inlayers
ranging from 0 to 10 feet thick underlain by a zone of highly weathered Austin chalk of thickness ranging from 0 to 10 feet. Under the weathered zone lies a more competent Austin chalk.
Previous expl orati on programs characterize the overlying soil s near the project site as residual soils which are derived from the disintegration of the rock below by the agents of
weathering and erosi on. These residual soils consist mostly of stiff clays, CL to CH material with some zones of MH, ML. and OH materials as defined by the Unified Classification System,
Water contents range from approx imately 10:1: to 40:1: wi th 1 i quid limi ts of between 20:1: and 85:1: and plasticity indices ranging from 5:1: to 60:1:, The overburden soil exhibits
swelling characteristics when subjected to changes in moisture content, The unit weight is approximately 100 to 110 pcf and 12 
o w o :t 10 cr => '" o z => ...Owa:'"0 .... 3: 􀁾􀀠20 o -' '" '" :;:l: W o 30 OVERBUROEN SOilS· Orgonic 10 inorgamc cloys 01 medium 10 high plastu:ily. some tat crays. Ol'g-Inie and
Inorganic SiltS. occaSional limestone frlgments AUSTIN CHALK· Primarily hmestone.lop ZOM is weathered and Ian 01 varying 􀁾􀁉􀁉􀁉underlain by un_there<!. liard. or.y IImesfone. Zones
ot tha'r limeslone present Ih/ougnOul the formation. FIGURE 8 GENERALIZED GEOLOGIC PROFILE HNTB -13
the unconfined compressive strength ranges from O.S to S.S TSF with most samples between 1 to 3 TSF. The internal angle of friction S, ranges from 10 to IS degrees with a cohesion intercept,
c, varying between 0.4 to 3.0 TSF. The engineering properties of the Austin chal k vary w1th the degree of weathering and the presence or absence of shaly zones within the sample. Table
A presents mechanical properties of weathered, tan, shaly gray, and hard gray limestone sampl es of the Austin formation as obtained from the exploration program for the Dallas North
Tollway project. Expected Ground Behavior Tunnel Excavation The Austin chal k is a rock of relatively constant composition with relatively low strength and varied bedding conditions
and should be easily excavated. "When freshly quarried the rock is soft and easily cut with a knife or saw, but on exposure to air many layers develop considerable hardness." (Shuler,
1918). Variations in the intact rock mass and its discontinuities may affect the rate and cost of excavation but are not expected to affect the feasibility of tunnel ing. Ground Stability
In general, underground excavations may be affected by several conditions that I ead to a requi rement for support or protection of the excavated surface, such as: o Stress redistribution
resulting in plastic yielding, creep, or formation of fractures. o loosening and movement along discontinuities. oSwell ing of the ground due to a reaction with water producing a voll.ll1e
increase of the material surrounding the excavation and inducing movement into the excavation. o Surface deterioration or decomposition of the material of the excavated perimeter due
to such mechanisms as air drying, slaking. or softening due to the presence of water. o Piping or washing by flowing water. 14 
TABLE A ROCK PROPERTIES OF THE AUSTIN FORMATION WEATHERED SHALY HARD ALL VALUES ARE IN PSI TAN GRAY GRAY LIMESTONE LIMESTONE LIMESTONE , MEAN 7.8x104 1.2x105 2.8xl05 i •I-r.tl >ST. DEVIATION
7.1xl04 2.6xl04 1.3xl05Z::l 􀁾􀀠W...l uC)::ILI..HIGH 1.4xl05 1.5xl05 4.9xl05zeOl<t 0 r.tl LOW 2.2xl03 9.4x104 1.2x105I I-:E :5 W , NO. OF SAMPLES 3 4 11 MEAN 503 1085 2040We 􀁷􀁾􀀺􀀺􀁲􀀺􀀠ST.
DEVIATION 503 250 584Zr.tll-r.tlC)Ll..wz HIGH 1250 1389 3653za:w00. a:U:EILOW 42 597 667ZOr.tl::Iu NO. OF SAMPLES 5 7 92 'Measured tangent at 50% of peak stress NOTE: ALL VALUES OBTAINED
FROM DALLAS NORTH TOLLWAY PROJECT· CONTRACT NO. DNT101-December 1, 1982 HNTB -15I 
A literature search of available geotechnical Information indicates that the tunnel s w1l1 be in good to exce11 ent quality rock (RQD 􀁾􀀠75,;) when sited below the weathered zones within
the Austin chalk. Thus, tunnel excavation is not expected to result in significant stress redistribution or accompanying elastic or plastic rock movements. The rock mass consists of
blocks formed by faulting or bounded by intersecting inclined joints or a combination of intersecting joints, bedding planes, and other discontinuities or planes of weakness. Loosening
and movement of these rock blocks are expected to occur during excavation. The mechanisms that can cause loosening and movement include: o Blast Damage -Gases under pressure may penetrate
joints and loosen rock wedges. Wedges may also be loosened by ground vibration. o Gravity -Gravity forces acting on wedges may cause separation or shearing movements along jOints or
bedding planes. o Strain Around the Opening -Creation of an opening in a stressed mass causes strain and deformation in the mass. Such strains tend to concentrate along natural planes
of weakness (such as jOints and bedding planes) and may loosen wedges, a110wing gravity to move them. o Shear Failure -Failure in shear may occur along jOints oriented at a critical
angle in the redistributed stress field about the opening. o Loss of Strength -The strength and tightness of the joint system may decrease because of absorption of water by, or air drying
of, joint filling materials. o Hydrostatic Pressure -The hydrostatic pressure due to groundwater in joints may induce loosening and movement of wedges. Loosening and movement of rock
wedges, slabs, and blocks may occur at any location in the tunnel excavations. The dip oK,joints or other planes of weakness and the; r strike wi th respect to the tunnel axis determi
ne the size and stabil ity of a wedge, its position on the tunnel perimeter, and its potential for loosening or falling. If supports are not installed, rock movement and the loosening
process may continue until a stable opening is formed. Most typically, the arch may break upward, across one or several bedding planes, until a competent roof or corbelled arch is formed.
For tunnels mechanically excavated, the excavation perimeter should generally require less support than that required for a drill and blast excavation of Similar size. 16 
Swelling of the ground is not expected if alternate wetting and drying of the rock surface can be avoided. Slaking of some areas may occur in shaly zones of rock when exposed to the
air by excavation. Surface protection and scaling of the exposed rock surface w1l1 be required. Piping or washing-out of ground may occur in heavily weathered rock or in fault zones
at tunnel elevation but should not occur within competent rock. Groundwater Infiltration Infiltration into the.unlined tunnels may be considerable as the fractured and broken nature
of the rock mass and observed high porOSity would indicate. Further investigation is needed to quantify the infiltration. For the concrete lined tunnel sections, water infiltration is
not considered a major problem. The use of a pennanent, impenneable membrane may be considered to minimize nuisance drips and seeps within the tunneled roadway. 5.0 TUNNEL EXCAVATION
AND INITIAL SUPPORT Excavation Alternatives The Keller Springs Road tunnel may be excavated using either drill and blast techniques or mechanically by means of a roadheader type of machine.
The approaches to the tunnel may be excavated using conventional surficial earthmoving techniques near the ground surface and drill and bl ast or a road header type machine at depth.
Final detennination of the method or methods to be used should properly I ie with the contractor. The short length of tunnel generally prohibits the use of a roadheader or similar equipment
purchased exclusively for this job; however, appropriately sized existing machines could be used. Drill and blast tunnels may require additional support because of weakening and fracturing
induced by blasting. Concrete quantities may also increase due to overbreak. The required size and shape of the tunnel s generally dictate that the tunnels, whether constructed using
drill and blast or mechanical means, be constructed with a top heading and bench excavation sequence. Such an excavation sequence allows the support and stabilization of the rock arch
before the removal of the lower tunnel sections in a quarry-type removal operation. In areas of faulted or weathered rock, in which at least some 17 
of the tunnel length should be expected, the heading and bench method is adaptable to conditions as they are exposed allowing variation 1n length of round, size of opening, and support
technique. Norma11y, the tunnel top heading would be excavated and supported from one end (portal) to the other fo11 owed by the benchi ng down to invert. This sequence of excavat i
on is directly applicable to the deep tunnel alternative, located below weathered rock. zones, but requires some modification for use in the construction of the shallow tunnel alternative.
Because the sha110w excavation alternative is sited within mixed face zones of soil. weathered rock and good qual ity rock, excavation must be performed in more stages of sma11 er si
ze than would be required in tunnels constructed in better ground conditions. A typical excavation sequence for the shallow tunnel alternative is shown in Figure 9. Fo11owing the excavation
the final cast-In-place lining would be placed; ceiling panels, wall tiles, and the required utilities and finished roadway would then be installed. Initial Support and Surface Protection
The initial support systems used must be adaptable and capable of supporting the range of loads antiCipated. The following alternative initial support systems may be used: o Structural
steel supports o Rock reinforcement -Rock bolts (tenSioned, fully grouted, or -Rock anchors or dowels (untensioned,encapsulated) encapsulated)fully grouted, or o Shotcrete Any of these
support systems or combinations of them may be used within the 1 imitati ons of compati bil ity with the ground behavi or encountered. The choice and design of the initial support system
for all excavations should be made by the contractor and should be compatible with the final support and lining requirements. To minimize loosening loads and degradation of the rock.
mass around the excavation, the initial support system should be installed closely behind the newly exposed working face. Ground control in typical tunnel reaches 18 
• 10'-0" MlrJlN!Utv1 t:.t7ve.R. 􀀭􀀻􀀽􀀻􀀽􀀫􀁾􀀻􀁾􀀻􀀻􀁾􀁾􀁾􀁾􀀻􀀻􀀺􀀻􀁾􀀻􀀺􀁾􀀭􀁲􀀭􀀭􀁲􀀽􀁉􀁏􀀧􀀭􀁏􀀧􀀱􀀠TAN) .. .. :::: 􀁾􀀮􀀠􀁾􀀠􀁫􀁬􀁥􀁁􀁾􀁥􀁥􀁰􀀠LI Mt!S1?>fo/e :.IARP, GeAY Lr 􀁍􀁥􀁾􀀧􀀱􀁬􀀧􀁬􀁉
􀁉􀁥􀀠SEQUeNce OF e.Xc.C\VAnON: r. PIL.OT 􀀱􀁕􀁾􀁾􀁥􀁌􀀮􀀠l!A 'lI'S. lop SIPe r::teIF15 1IIA t Elf!,. !3O'TTZ'VI SIPe DR/Frs JllA t 11715. C.ReMlN DfelPrS .JZ". seNd4 EXCAVA"OOt..l 􀁆􀁩􀁾􀁉􀁊􀁾􀀨􀀯􀀧
􀀠9 EXCIIVA1701J SBJ)()eJC£ 1fJR. SHliu..ow 7k10 -LANe '1VAlN€"L , ..' .....-.w...-....M_.& __.......... 
may be limited to removal of loosened wedges or the installation of spot rock reinforcement. The number and location of loosened wedges will vary with discontinuity and bedding patterns
and the other factors described above. Wedge loosening may be generally less frequent in small openings and in openings excavated by mechanical means. Close-spaced joints, faults, shear
zones, and weathered rock may affect initial support requirements. Minimizing ground control probl ems may be accompl ished by an extensive program of pre-grouting the tunnel interval
from the ground surface prior to construction. Such a program is considered to be essential to the success of the shallow tunnel alternative because of the extensive weathered rock zone
known to exist within Dallas County. Based upon the antiCipated geologic conditions, the construction cost estimate of Section 8.0 assumes the use of structural steel rib support for
the tunnel excavations of both shallow and deep tunnel alternatives. These ribs would be cast integrally within the concrete final lining forming the tunnel final support. While both
shotcrete and rock reinforcement either singul arly or in combination generally appear more economical than using steel ribs, they require greater technical proficiency and skilled workmanship
to install and are not easily adapted to ground conditions which may be exposed if weathered or faulted zones of major extent reach tunnel IeveI • Groundwater Control Groundwater inflows
will be encountered during tunnel construction and the contractor should have a plan to deal with inflows that will affect construction operations. Most of the large groundwater inflows
are expected to be in the form of flows from rock discontinuities which must be controlled in the completed tunnel. Infiltration should be controlled by grouting as the excavation progresses
to prevent loss of ground from pi pi ng or washi ng by water and the development of waterways outside the tunnel. 20 
6.0 FINAL SUPPORT AND LINING At some time following the erection of the initial support.system consisting of rock reinforcement and/or shotcrete or structural steel ribs, a final lining
will be erected within the tunnel opening similar to that shown in Figures 4 and 5. The final lining is designed to withstand all loads that may be imposed during the tunnel's service
life. The beneficial effects of any initial support system are generally neglected in the design of the final lining; however, structural steel ribs used as initial support may be included
as a composite design for tunnel final support. The loading considered in the deSign of the final lining are: 1. Ground Loading Due to the shallow cover present at the airport site and
the weathered rock profile, the tunnel should be deSigned to sustain a uniform ground load of full overburden of approximately 30 feet of ground measured to tunnel crown for the deep
tunnel alternative and 10 feet of ground pI us impact loadings for the shallow tunnel aHernative. 2. External Hydrostatic Pressure -Tunnels should be designed to sustain external hydrostatic
pressures. 7.0 SPECIAL CONSIDERATIONS Tunnel Ventilation Ventilation of roadway tunnel s is normally provided to ensure dilution of exhaust fumes to acceptable concentrations. At present,
for gasoline powered engines, the dominant constituents for which dilution is required are CO and CO2, Provided these constituents of the exhaust gases are adequately dil uted, there
will be no harmful effects from other substances such as S02 and lead. Determination of ventilation air volumes for design purposes, the length, inclination of the roadway, the number
of lanes, vehicle capacity, and traffic composition are taken into account. The tunnel user will normally be exposed to the atmosphere of the tunnel for a period of only one minute for
which a maximum 1evel of 125 ppn CO for a normally congested urban expressway is considered acceptable. The proposed tunnel lengths are generally within the range at which artificial
ventilation should be considered, especially since traffic flow within these tunnels may be subject to congestion during peak flow periods. 21 
This traffic flow will be controlled by the traffic signal timing at the nearby intersection of Keller Springs Road and Addison Road on the east and Midway Road on the west. While detailed
analysis may, during final design, conclude that only exhaust ventilation will be required, provision is made in this study for a semi-transverse ventilation system for both shallow
and deep tunnel alternatives. In this system, air is delivered along the entire length of the tunnel at a uniform rate and the noxious fumes and smoke emitted are diluted and removed
via the portals. The size of the supply air duct is a function of air flow requirements, allowable air duct velocities and the tunnel internal geometry. Generally, air flows are maintained
to a maximum air duct speed less than 5,000 feet per minute for optimal operation. Providing for semi-transverse ventilation ensures that the tunnel size is large enough to provide the
required ctucting above the traveled roadway. If an automatically activated exhaust only system or a longitudinal type system is later determined the most efficacious, sufficient airway
and headroom capacity is provided without enlargement of the tunnel excavation requiring a simpler and less costly mechanical system. Assumed characteristics for ventilation design Geometry:
length: 1,000 feet each Altitude: 640 feet above MSl Grade: leve I Traffic: Heavy from date of first service, particularly during A.M. and P.M. rush hours. Approaches normally uncongested
except at peak periods. Heavy truck traffic less than ISO/lane-hour. Pollution levels: (CO) Nature of Tunnel: City street; one way traffic each tunnel; normally congested Uncongested:
30 ppm Threshold of Congestion: 125 ppm Maximll1l Traffic Volll1le: Congested Roadway -900 vehicles/lane at 5 mph Free Moving Roadway -2,000 vehicles/lane at 35 mph 22 
Required Vent11 ation per Lane: 860 cubic feet/second/lane for CO dilution 1,640 cubic feet/secondll ane for fi re protect ion (controls)2 lane tunnel = 196,800 cubic feet/min 3 lane
tunnel =295,200 cubic feet/min InstaII ed Horsepower per Tunnel (2 tunnels requi red): 200 horsepower (268 KW) (2 lane tunnel) 300 horsepower (402 KW) (3 lane tunnel) To ensure tunnel
ambient atmosphere conditions are adequate at all times a carbon monoxide monitoring system should be provided in the tunnel. These sel f-contained systems monitor concentration in ai
r of CO at a number of remote sample points with up to three levels of alarm indication and ventilation control. These systems are now fabricated in modular construction and solid state
circuitry to enhance reliability and simplify maintenance. Tunnel Drainage Within the tunnels, major concerns for drainage are: 1. handling the unexpected spills of water or fluids from
tank trucks or inflows of water through the tunnel walls, 2. handl ing of rainwater intercepted at portal s and runoff from traveling vehicles, and 3. handling of washdown water. Trench
drai ns may be provided at tunnel portal s to intercept water from approach roadways. Each trench drain at tunnel portals should be equipped with individual sumps to prevent the introduction
into the tunneled sections of flammable or hazardous materials spilled near portals. At tunnel low points, approximately mid-length, a common sump built into a cross passage between
tunneled roadways may be constructed. Here a trenchtype drain may collect runoff or fluids spilled inside the tunnels. The approach roadway and portal trench drains are generally handled
by a single pump station and conveyed to local storm drainage systems. The pump 23 
station at the tunnel midpoint may be packaged units with outfall conveyance outside the tunnel by a drainage force main constructed within the tunnel walls. Tunnel Lighting The amount
and type of tunnel lighting depend on the tunnel geometry, the materials comprising the inside finished surface, and the size of the excavation. The 1 ighting provided should be adequate
to provide time and brightness for the eyes of drivers entering the tunnels to adapt to the change of 1 ighting intensity, from a working dayl ight (8,000 footcandles (fc)) to approximately
5-10 fc, the level maintained for general tunnel artificial lighting. To minimize the length of transition zones from the exterior brightness to interior levels of brightness requires
transition, generally taken at such levels so no reduction of level of brightness exceeds a ratio of 10:1 for brightness of adjacent zones of tunnel. To el iminate threshold I ighting
at portal s and intermediate brightness transition required, sunscreens should be used. These sunscreens are interposed between the open depressed roadway and tunnel portal s. The sunscreen
cut the brightness level from the 8,000 fc to 800 fc followed by a threshold zone requiring 80 fc and interior tunnel zone at 8 fc, with no transition zone required. Interior tunnel
lighting may be provided by fluorescent lamps. (Two fluorescent lamps in opposite corners of the tunnels will yield sufficient levels of average interior illumination of the running
tunnel section.) Where lighting requirements require larger intensity. such as the transition zone at portals, combinations of fluorescent lamps and the more efficient low pressure sodium
lamps may be used. Wall and Ceiling Treatment The interior of a vehicular tunnel is a harsh environment. The lining must be capable of withstanding the punishment of road grime. exhaust
fumes, 24 
hose cleaning, as well as impact from vehicles. and in emergencies. the temperatures from fire. Such 1 inings must not be capable of sustaining combustion nor give off toxic or hazardous
combustion by-products. Structural glazed facing tile appears to be the one element which best fulfills these requirements for tunnel sidewalls and has been successfully used in other
tunnels of similar type throughout the United States. Mineral wool sprayed to a depth of approximately one inch has been used for a ceil ing coating. Mineral wool, besides providing
1 ightweight fireproof material has an excellent noise reduction coefficient. Fire Fighting No special fi re prevention and protection methods are proposed for the tunnels. Fire hose
connections will be made via Siamese connection located every 200 feet along the tunnels. Siamese connections should be located at each tunnel portal. This will allow fire fighters to
gain access from either end of the tunnels and connect their hoses to standpipes without having to lay lay 11 nes a long the ent ire I ength of tunnels. The stand pi pes shoul d be dry
until needed. Fire detectors may be deployed within the tunnel to detect heat generated by fire. These alarms maybe directly wired to the central alarm station for immediate fire department response. Tunnel ventilation systems should be reversible and capable of exhausting fumes and smoke from
the tunnels. In such cases, air will enter tunnel portal s and be exhausted from the ventilation system ensuring dilution of smoke and a respirable environment. 8.0 CONSTRUCTION COSTS
AND ESTIMATES Feasibility level construction estimates were made for comparison of alternatives and are given in Tables Band C. Estimates were prepared for two 2-1 ane tunnel s and for
two 3-1 ane tunnel s for the deep tunnel alternat i ve under the Addison City Airport. Estimates were prepared only for two, 2-lane tunnels for the shallow tunnel alternative. 25 
TABLE B DEEP TUNNEL ALTERNATIVE PRELIMINARY CONSTRUCTION COST ESTIMATE Item Preparati on of R/W & Removals Concrete Pav; ngBridges, Retaining Walls Excavation (Non-Tunnel)DrainageTunnel
(Complete)Signing, Striping, Lighting Utility Relocations Mobilization ContingenciesEngineering, Administration, Materials Testing Total Four-Lane Option $ 130.000 425,000 6,500,000
3,500,000 600,000 11,400,000 40,000 50,000 450,000 3,455,000 2.250.000 $28,800,000 TAlllE C SHALLOW TUNNEL ALTERNATIVE PRELIMINARY CONSTRUCTION COST ESTIMATE (4-Lane Facility Only) Item
Preparation of R/W & Removal s Conc rete Pavi ngBridges. Retaining Walls Excavation (Non-Tunnel)Drai nageTunnel (Complete)Signing. Striping. Lighting Utility Relocations Mobil ization
ContingenciesEngineering, Administration, Materials Testing Total 26 Six-Lane Option $ 160.000 600,000 7,500,000 5.200.000 800,000 17,100.000 45,000 60,000 600,000 4.835.000 3.300,000
$40,200,000 Amount $ 130,000 425,000 3,500,000 1.375,000 450,000 17.600,000 40.000 50.000 500,000 3,530.000 2,400,000 $30,000,000 
The estimated construction cost for the deep two, 2-lane option is $28.8 million, and $40.2 million for the deep two, 3-lane option. The cost for the shallow two, 2-lane option is estimated
to be $30.0 million. The estimates are based upon: 1. Prevailing prices as of July, 1985. 2. Tunnels are excavated by drill and blast methods. 3. The excavation sequence shown in Figure
9 is used for the shallow tunnel alternative. 4. Structural steel ribs are used for tunnel initial support. 5. Tunnel final lining and geometry are as shown in Figures 4, 5, and 6. 6.
Tunnel plan and profiles are as shown in Figure 3. 7. Open cut roadway approach sections are included. 8. Costs do not include rfght-of-way acquisition costs. 9.0 CONCLUSIONS AND RECOMMENDATIONS
Based upon a review of the subsurface condi ti ons applicabl e construct ion techniques and support methods, it is generally concluded: Tunneling 1. Tunneling is a feasible construction
technique. 2. Subsurface conditions are generally similar throughout the study area. 3. (a) The deep tunnel alternative will be constructed within the Austin chalk with approximately
30 feet of cover. (b) The shallow tunnel alternative will be constructed 1n soils or weathered rock with approximately 10 feet of cover. 4. Tunnels will be constructed using conventional
drill and blast techniques although a roadheader-type excavation is feasible. 5. In weathered rock and SOils, multiple small drifts are required to allow safe tunneling. 6. Applicable
alternative initial support systems are: (al Structural steel ribs (b) Rock reinforcement and shotcrete 7. Final lining will consist of reinforced cast-in-place concrete. 8. Tunnels
will be provided with semi-transverse ventilation systems. 27 
9. Tunnels will be provided with lighting systems to obtain a minimum of 5 to 10 footcandles illumination. 10. Tunnels will be provided with a drainage system to collect portal inflow
and internal collected water. Recommendations 1. Unless traffic flow predictions justify otherwise, the 2-lane alternative appears significantly less costly. 2. Whil e the depth of approach
roadway open cut shoul d be minimi zed to reduce the cost of approach roadway the increased cost of shallow tunneling generally negates such savings. 3. The possibility of increased
surface subsidence and unpredictable catastrophic losses of ground increase with shallow tunneling in weathered rock and soil generally dictating deeper tunnel ing as the preferred alternative.
4. An open cut alternati ve wi th cut-and-cover (decked) porti on at within the runway/taxiway area would not appear feasible. Construction of such sections would greatly impact airport
operations and construction cost savings are not apparent. 5. If further studies indicate feasibility, a geotechnical investigation should be undertaken within the study area to confirm
the cover and rock quality assumptions made herein. 10.0 REFERENCES Ameri can Soc i ety of Heati ng, Refri gerati on and Ai r Conditi oni ng Engi neers (ASHRAE) Application Handbook,
1982, Chapter 13. Bickel, J.O., and ToR. Kuesel, editors, 1982 "Tunnel Engineering Handbook," Van Nostrand Reinhold Company, Inc., New York. Mason-Johnson & Associates, Inc., 1982, "Geotechnical
Engineering Report, Phase I, Dallas North Tollway, Dallas, Texas," Contract No. DNT 101, prepared for the Texas Turnpike Authority, December I, 1982. Shuler, Ellis W., 1918, "The Geology
of Dallas County," University of Texas Bulletin, Bureau of Economic Geology and Technology, No. 1818, March 25, 1918, Austin, Texas. 28