HomeMy WebLinkAboutZMA202100011 Correspondence 2022-04-28TECHNICAL MEMORANDUM
To:
John Wilson, PE
CC:
Kevin McDermott
Scott Collins, P.E.
From:
Cad Hultgren, PE, PTOE
Date:
April 28, 2022
GOROVE SLADE
Transportation Planners and Engineers
VDOT — Charlottesville Residency
Albemade County
Collins Engineering
Gorove/Slade Associates
Subject: The Heritage on Rio— Response to Traffic Impact Analysis (TIA) Review Comments
While at Ramey Kemp & Associates (RKA), we submitted the revised TIA for this proposed multifamily community on February
4, and the Virginia Department of Transportation (VDOT) provided review comments in a letter dated March 14. 1 joined Gorove
Slade on March 1, and the applicant asked me to address the review comments. The purpose of this memo is to provide a
response to the review comments based on our conversation on April 19. Following are the review comments, and our response
to each comment:
a. Townwood Drive / Earlysville Road & Hydraulic Road / Rio Road West (Existing, Background and Build conditions)
I. Page 1, Comment ii: Previous comment about using Max 1 time does not appear to have been addressed.
Response: We did address this comment in the February 4 TIA — there is no data in the Time -of -Day (TOD) Functions tab
related to Max 2, so we applied Max 1 as instructed.
ii. Page 2, Comment iii: Please code vehicle extension per signal timing data.
Response: We typically do not change the default vehicle extension in Synchro. It has little or no effect on the LOS, delay or
queue calculations because most phases max out during the AM and PM peak hours, so the extension time is irrelevant.
b. Berkmar Drive & Rio Road West (Existing, Background and Build conditions)
I. Page 2, Comment is Northbound and Southbound phases have not been coded per previous comments; they do not match
signal timing data. Please code vehicle extension per signal timing data.
Response: In the Synchro models, we inadvertently switched the labels on Phases 4 and 7, and on Phases 3 and 8. If we
correct those labels, the split timings would not change, and there would be no change to the LOS, delay or queue calculations.
We typically do not change the default vehicle extension in Synchro. It has little or no effect on the LOS, delay or queue
calculations because most phases max out during the AM and PM peak hours, so the extension time is irrelevant.
ii. Page 5, Page 7 (Table 2): TOSAM (v2) only references standard control delay outputs from Synchro as MOEs and not the
argued "Lost Time" iterations for traffic operations analyses.
Response: We presented the Synchro results with and without the lost time adjustment to illustrate how important the lost time
adjustment is to the analysis. Without the lost time adjustment, the lost times at these signals range from 6.9 to 9.6 seconds per
movement, which are extremely conservative.
4951 Lake Brook Drive / Suite 250 / Glen Allen, VA 23060 1 T 804.223.5088 goroveslade.com
The Heritage on Rio - Response to TIA Review Comments
April 28, 2022
Page 2
c. Per TOSAM (v2), the higher of the Existing PHF or 0.92 should be employed for analysis of the future (Background, Build
etc.) conditions in urban locations.
Response: The existing PHF at the Rio Road West at Berkmar Drive intersection is 0.83 in the AM peak hour, and 0.93 in the
PM peak hour. The existing PHF at the Rio Road West / Hydraulic Drive at Earlysville Road / Townwood Drive intersection is
0.87 in the AM peak hour, and 0.88 in the PM peak hour. We applied these PHF's throughout the no -build and build analysis.
If we increased all the PHF's that are below 0.92 up to 0.92, that would actually improve the results presented in the February 4
TIA.
The March 14 review comments are focused on technical settings in the Synchro traffic models for the signalized intersections
that have little or no impact on the overall results. In fact, if we increase the PHF's to 0.92 for the no -build and build conditions,
the results would improve - resulting in shorter delays and queues.
As noted in the February 4 TIA, the proposed site trips are projected to increase the total approach volume at the Rio Road West
at Berkmar Drive intersection by just 3%, and the total approach volume at the Rio Road West / Hydraulic Drive at Earlysville
Road / Townwood Drive intersection by just 1 %, so no improvements are warranted at these intersections.
When we discussed these comments on April 19, we agreed that revising and resubmitting the Synchro analysis is not necessary
in this case, and the recommendations in the February 4 TIA are still valid. We appreciate your attention to this matter, and trust
that our responses satisfy all VDOT concerns.
4951 Lake Brook Drive / Suite 250 / Glen Allen, VA 23060 1 T 804.233.5088 goroveslade.com