380 Maple West — Comments/Questions on Transportation Impact Study

The following was sent thru Town staff regarding the Transportation Impact Study for 380 Maple Avenue West.

A few overarching comments regarding my review for staff:

  1. WRA Comment #2 – Town staff need to settle and agree which Synchro files were sent to WRA and which ones were sent to KHA…should be the same file set.
  2. We should update the requirements for analysis to HCM 6 and Synchro v10
  3. For a number of underlying reasons, Existing 2018 to Background 2020 LOS degraded by one level (D to E) at the following intersections/times of day):

– AM Peak Nutley St. and Courthouse Rd.
– AM Peak Nutley St. and Maple Ave. (and by 7 to 11 seconds but not by a LOS level for PM and Saturday)

Staff should pay particular attention to this as the timings are put in place for the new traffic signal system.

  1. Scoping… As per Traffic Impact Assessment for Site Development (ITE, 2010) the study area should include “…the first signalized intersection on each street serving the site…” Leaving out Maple Avenue and Courthouse Rd./Lawyers Rd. is problematic since this is the alternate departure route to reach Nutley St.
  2. MAC Application Checklist, Off Street parking – DPZ shows 151 parking spaces. The items here should be consistent with the transportation impact study, see Comment #12 below.
  3. Cut thru traffic potential neighborhood impact. Need to have a robust conversation about neighborhood access and install whatever the necessary devices in the public right-of-way as part of the project implementation. See Comment #13 below.

Here is a bullet list of my specific comments regarding the 380 Maple Avenue for their Consultant (Andy Smith at Kimley-Horn):

  1. 1 – “…include 147 parking spaces divided among garage and surface parking to…” What surface parking?
  2. 2 – Last line of first paragraph…think you mean PM peak hour?
  3. 8 – Introduction 3rd paragraph on changes to development program. Request that the Consultant describes the difference more specifically here and statement about what the change in trip generation and associated transportation impact as a result.  (Would prefer analysis based on actual program as that creates fewer questions and confusion from public…the dynamics of a “conservative” estimate are not well understood.)
  4. 9 – See comment #4 above.
  5. 25 – Trip generation for Vienna Marketplace. More detail needs to be provided here similar to comment on regarding page 3.  Request that the Consultant describes the difference in detail with impact of the change in trip generation and resulting transportation impact analysis. (Would prefer analysis based on actual program as that creates fewer questions and confusion from public…the dynamics of a “conservative” estimate are not well understood.)
  6. 25 – Last paragraph. Include the specified 1.0% per year growth factor. from the scoping document here. In addition it would be helpful if the Consultant summarize the 5 year trend for Nutley St. and Maple Ave. traffic here from VDOT data (it has been declining) and the implication that a 1.0% per year increase is a conservative estimate. Further, it would be helpful to note in the bullet list of pipeline projects what their study assumption was for background traffic growth.
  7. 43 – Table 9: Site Trip Distribution. 1) no associated map/diagram of the directions of approach percentages associated with Table 9 provided. For the lay person it is a hard to discern where the percentages were applied.  Request the consultant provide such a map/diagram, 2) Arguably, a number of the “to the south on Nutley Street” will depart by making a right turn out of Wade Hampton to a right turn on Courthouse Rd. (perhaps Pleasant St.).
  8. 36 and pg. 57. – 1st paragraph on each page. Since the background and future conditions include pipeline development which includes the 444 Maple Ave. project their proffered traffic signal timing, phasing and left turn lane length changes should necessarily be included. This, I believe, is in their total future analysis…staff should check to confirm.
  9. 57 – Total future northbound Wade Hampton delays of 4 to 6 minutes is problematic. Request that the Consultant provide revised analysis of the effect of the proposed revision to the  lane configuration. Refer to Comment #7 is outbound traffic to WB Maple Ave headed west to Oakton or to Nutley street; consider effect of directions of departure percentages.  Delay value based on traffic gaps; are their signal timing strategies at Maple Ave/Nutley St. or Maple Ave./Courthouse Rd. that could create gaps. “DON’T BLOCK INTERSECTION” limit lines an signs…just propose that they should be installed.
  10. 61 – Queuing analysis. Is the 25 ft. / vehicle conservative, average, 85th percentile?  What does a 95% percentile queue mean for the layperson?
  11. 63 – TDM with the website idea, provide computer/monitor in lobby that provides NextBus information.
  12. 64 – Parking demand. Please specific whether this analysis incorporates the conceptually proposed intermediate parking floor or not. Coordinate w/ staff on the number required vs. the MAC Application Checklist, see Comment #5 above. Study lists 147 and staff checklist uses 151. Are any of the incentives taken? Please note if so, or if not.
  13. Cut thru traffic potential neighborhood impact. Need to have a robust conversation about neighborhood access and install whatever the necessary devices in the public right-of-way as part of the project implementation. See Comment #6 above.
  14. General comment. There is no description of the change in pedestrian or bicycle facilities as part of the project development. At a minimum the physical changes is sidewalk width and provision of bicycle parking should be described.

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