HomeMy WebLinkAboutC_Transpo_TIA_Comments.191202
12131 113th Avenue N.E., Suite 203, Kirkland, WA 98034 | 425.821.3665 |
TG: 1.19297.00
December 2, 2019
Matt Herrera
Senior Planner
City of Renton
1055 S. Grady Way
Renton, WA 98057
SUBJECT: CEDAR RIVER APARTMENTS TRAFFIC IMPACT ANALYSIS REVIEW COMMENTS
Dear Mr. Herrera:
We have completed our independent review of the October 21, 2019 Traffic Impact Analysis (TIA) prepared by William
Popp Associates for the Cedar River Apartment project proposal on behalf of the City of Renton. We recommend the City
require an updated TIA in response to the following review comments:
Pages 3, 20, Table 6. Trip Generation. The Phasing Plan and Architectural Sheets submitted as part of the application
indicate the Medical Office building planned as part of Phase 3 will be a total of 50,000 square feet (two floors of 25,000
sqft), instead of the 25,000 square feet assumed in development of the trip generation estimates. The trip generation
estimates in Table 6 and the resulting traffic operations analyses should be updated accordingly.
Page 22. Trip Distribution. The distribution of site-generated traffic should be presented following the Policy Guidelines
for Traffic Impact Analysis for New Development, May 2013. The City’s guidelines state that the distribution should be
presented by direction as a percentage of the total site generated traffic in a graphic format. Include a trip distribution
figure to illustrate how the distribution patterns were converted into project trip assignments.
Page 23 & 24. Figure 7a & 7b. It appears that the pass-by trips were not included in the figure and the operations
analysis. The pass-by trips should appear as adjustments to the turning movement counts at the site access locations.
The analysis should be updated to account for the pass-by trips.
Page 35. Intersection LOS Analysis. The turning movement volumes for 2023 “With Project” AM and PM scenarios are
not consistent for some movements between volume graphics (Figure 8b and 9b) and the Synchro worksheets in
Appendix C.1.c and C.2.c. The Synchro and corresponding SimTraffic analysis should be updated to use consistent
turning movement volumes shown in the graphics.
Page 35. Peak Hour Factor (PHF). The PHF used in the SimTraffic analysis (1.00) is not consistent with the Synchro
analysis (0.90). The WSDOT Synchro & SimTraffic Protocol, August 2018, referenced in this analysis only provides
guidance on reasonable range of the PHF to use for the Synchro analysis, with no direction for SimTraffic. Without PHF
provided for the existing turning movement counts, the future PHF could be estimated based on Table 19 from NCHRP
Report 599. The 0.90 PHF should be justified for use in the analysis, or the PHF should be updated to use recommended
values from NCHRP Report 599. Additionally, the SimTraffic analysis should utilize the same PHF as the Synchro
analysis for consistency purposes.
Page 38. SimTraffic Simulation Period. The analysis uses a 30-minute simulation rather than a commonly used 60-
minute duration as representation of the peak hour. The SimTraffic analysis should be updated to use a 60-minute period.
Mr. Matt Herrera
December 2, 2019
Page 2
Page 38. Table 8. Scenarios Evaluated. A Year 2023 scenario with the Project, but before implementation of the
WSDOT ETL project should be evaluated in SimTraffic. The TIA should be updated to include this additional scenario in
the SimTraffic results. The updated traffic operations analysis should clearly demonstrate that the trips generated by the
Project will be able to be processed by the Cedar River Park Drive intersection during the AM peak hour when the
westbound maximum queue on SR 169 extends for nearly 4,500 feet.
Page 38. SimTraffic Files. Please provide the actual SimTraffic files so the results can be reviewed more closely.
Page 42. Parking. The parking analysis should include information from the Renton Municipal Code (RMC) that identifies
the number of stalls required for each of the proposed land uses. It should be specified that for the proposed medical
office (Building C), RMC requires 5 stalls per 1,000 net floor area. A table format is recommended to summarize and
identify the differences between the parking required by RMC, the estimated parking demand from the King County Multi-
Family Residential Parking Calculator, and the proposed parking supply. The table should include the proposed parking
supply for each land use, and note key differences from the RMC. In addition, bicycle parking should be provided with
specified minimum requirement in RMC. Finally use of the King County Multi-Family Residential Parking Calculator should
be justified as a reasonable comparison tool for this specific location.
Page 48. Frontage Improvements. The discussion should be updated to identify the specific width allocated for utilities
and landscaping behind the sidewalk. Currently no width has been identified.
Page 49. Secondary Site Access - Location. The location of the access point should be consistent with the 350 feet
described on page 45. In addition, the proposed location of this access point is where the 3-lane section of southbound
SR 169 transitions to a 2-lane facility. Drivers in the right most lane would need to pay additional attention to a vehicle in
front that may turn into the driveway, while also trying to find a gap to merge left. Locating a driveway in the vicinity could
be a potential safety issue due to the multiple vehicular movements taking place. More information should be included
about the interaction between the merging vehicles on SR 169 and the site access vehicles. Otherwise, the southbound
lane transition may need to be modified to allow for a safe transition.
Page 49. Secondary Site Access – Left-Turn Restriction. We are concerned about the proposed mountable “pork-
chop” concept as they are not always effective in preventing left-turns in or out. Was the installation of C-Curb considered
to restrict the left-turn movements at this location, or some other form of access management?
Thank you for the opportunity to assist in this review. Please do not hesitate to contact me at 425.821.3665 should you
have any questions about our comments.
Sincerely,
Transpo Group
Jon Pascal, PE, PTOE
Principal