Joel,
Yes, smoothness is a very valid concern. And I know that the Town had something similar years ago on Beltline Road.

We've seen similar "speed bumps" appear during the rolling process. Commonly the "rebound" of the mat is due to the underlying (& excess) crack sealer from the previous project. When
something like that happens, our inspectors will immediately halt production until we've figured out the problem.

Also, the current FAA paving spec includes smoothness as an acceptance criteria. Specifically, the finished surface may not vary more than ¼" when using a 16' straightedge. Both longitudinal
& transverse smoothness are checked at 50' intervals. If 15% or more fails, the section is milled & replaced.

And, the FAA recently added a "finished grade" survey where the Contractor is required to survey the finished profile. And like smoothness, if 15% or more fails, the section is milled
& replaced.

Finally, regarding the design, the profile will have very long vertical curves for a smooth ride.

All that to say, we understand your concern and the need for smoothness.

Have a good weekend.
P. Timothy Siemens, PE
Garver, LLC
From: Jenkinson, Joel [mailto:Joel.Jenkinson@wgint.com]
Sent: Friday, December 11, 2009 1:52 PM
To: McIllwain, Frank O.; Siemens, Paul, T
Cc: Joe; david.foster@addisonairport.net; macevedo@addisontx.gov; Nancy Cline; Clay Barnett
Subject: Runway Resurfacing

Gentlemen,

            I know you are wrapping up the PER right now, but there is something I wanted to bring up with you regarding the final design. This is a concern that stems from the bad experience
I had with the runway overlay we did when I was at New Orleans Lakefront.  On that project, the contractor turned what had been a good smooth runway into something that more closely
resembled a waffle.  We got pilot complaints about it for years afterwards, so naturally it is something I would very much like to avoid with our upcoming overlay here in Addison.

            There were some basic problems with that job, not the least of which was the competence (or lack thereof) of the engineer; at least I am confident we will not have that particular
issue on this job. In the bid specifications, there was effectively no standard or measure of either longitudinal or lateral smoothness that the contractor had to meet.  All of the focus
was on obtaining maximum compaction of the asphalt, with the specs written in such a way that the higher the compaction (PWL), the higher the payout.  So of course the contractor focused
on maximizing his payout with aggressive use of vibratory rolling.  The adverse effects of this were apparent when the very first lane of asphalt was put down and they pounded some big
dents in the runway.  The engineer didn't stop them and make them revise their methods, so they just filled in the lower spots with more asphalt and kept right on rolling (over the screaming
objections of airport staff, which went unheeded). Anyway, the job went poorly and we had an undulating runway when it was all done.

            So this is probably just my oversensitivity based on a previous bad experience, but given the phasing and the way we will likely have to construct this overlay, the smoothness
of the finished product is a major concern for me.  I very much want to assure that there are appropriate standards and measures for the smoothness of the finished surface in place,
so the contractor has every incentive to insure that the finished product will be at least as smooth as - and hopefully even better than - what we have out there now (which is actually
pretty good, in spite of the fact that some low spots have developed here and there).  So I just wanted to bring this up now, to make sure we address it in the final design and the bid
specs.

Thanks,

Joel

[cid:image001.jpg@01CA7A6C.BEF9D0A0]
Joel Jenkinson
Director, Addison Airport
  main: (972) 392-4850
  fax: (972) 788-9334