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TECHNICAL MEMORANDUM
Project: Kennydale Gateway
4350 Lake Washington Boulevard N, Renton, WA
Subject: Response to City Comments about Transportation
Date: August 15, 2022
Author: Marni Heffron, P.E., P.T.O.E.
This memorandum responds to the City of Renton’s consultant comments related to transportation. These were presented in a memorandum: Kennydale Gateway Transportation Impact Analysis Review
Comments, Transpo Group, July 2022. That memorandum stated that the comments related to: “the June 2021 Traffic Impact Analysis (TIA) prepared by Heffron for the Kennydale Gateway project proposal as well as the Response to Comments dated March 2022.” As recommended, these comments have been incorporated into a Transportation Impact Analysis – Revised (TIA). The Revised TIA also integrates the analysis from the prior response. The specific transportation-related comments are listed below followed by responses. The Revised TIA will be submitted as a separate document.
City’s Consultant Comments and Responses
Comment 1: Page 1. Introduction and Project Description. Provide context within the introduction including detail of N 44th Street southbound on-ramp. Also provide a site vicinity map to orient the reviewer to the site and the surrounding transportation network. Response: The Revised TIA adds a vicinity map and more detail about the site’s relationship to the interchange. Comment 2: Page 2. Figure 1: Site Plan. The site plan appears to include a southern access. Please identify this access in the discussion. Also, unless this access is an emergency access, update study to include this driveway in the analysis. Response: The southern driveway will be for emergency access only. The only public access to the site will be through the driveway opposite NE 43rd Street. The project will construct a roundabout at the intersection of Lake Washington Boulevard N / NE 43rd Street / Site Driveway as anticipated by
the Washington State Department of Transportation (WSDOT) in its improvement plans for the I-405/NE 44th Street interchange. The Revised TIA has an expanded description of the proposed site access, including information about the planned emergency access.
Comment 3: Page 3. Horizon Year. Confirm if horizon year is still anticipated to be 2024 for the completion of the interchange and Stride BRT. Link provided in the report now suggests a future 2026 horizon year. Update horizon year to be consistent with current plans.
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Response: The “I-405/Renton to Bellevue Widening and Express Toll Lanes Project” is under construction. The current schedule predicts that the project, including the interchange improvements
at N 44th Street, will be complete and open to traffic in Fall 2024.1 This is the same timeline that was expected in the TIA, but the schedule reference has been updated in the new report. Sound Transit’s I-405 Bus Rapid Transit (BRT) project would occur later, with service expected to commence in 2026 or 2027.2
The proposed Kennydale Gateway project is expected to be completed and occupied in the 3rd quarter of 2025. This would be after WSDOT’s major interchange project is complete, but before Sound Transit BRT service begins. Therefore, the year 2025 traffic volumes are appropriate for this analysis. The delay in the BRT service is not expected to result in any adverse operating conditions at the interchange since WSDOT’s analysis that all new interchange intersections would continue to operate at acceptable levels of service in 2045 is more than 20 years beyond anticipated opening.
Comment 4: Page 4. Site Trip Generation (Apartments).
A. Provide support for suggested increase from current transit 7.2% to suggested 20% reduction assumed in the analysis. Did the Sound Transit study include transit ridership projections at the new BRT station? What other information can be provided to justify the 20%. We recognize it is an assumption, but more documentation to support it should be provided.
B. Per ITE Trip Generation Handbook Flow Chart AM and PM peak hours should be estimated
per the average rate as both have R squared values less than 0.75.
Response: A new edition of the Institute of Transportation Engineers (ITE) Trip Generation
Manual was issued in September 2021, after the prior version of the TIA was prepared. The revised ITE trip generation data were applied to the current project program, which proposes to construct 385 units (the prior TIA evaluated 390 units) and 1,500 square feet (sf) of commercial use. The new edition includes updated rates and equations for Multifamily Housing (Mid-Rise) (Land Use 221) in a General Urban/Suburban setting, and includes rates for projects “Close to Rail Transit” or “Not Close to Rail Transit.” Although the site would be close to high-frequency transit, data for a site “Not Close to Rail Transit” were used and likely result in a conservatively high estimate of project-generation traffic. The new manual includes three categories for retail uses that vary based on the total size. For this analysis, rates and equations for Strip Retail Plaza (<40k) (Land Use 822) were applied based on the small amount of commercial space proposed.
The flow chart and guidance for selecting trip generation rates or equations in ITE’s Trip Generation Handbook state that, if a land use has a fitted curve equation and there are 20 or more data points, then the fitted curve equation should be used. If there is an equation and fewer than 20
data points, then the selection depends on the value of the equation’s R-squared (≥0.75) and standard deviation of the average rate (≤55%). For daily trip generation of the residential use, there are fewer than 20 data points, the equation’s R-squared value is 0.93, and the standard deviation is less than 12% of the average rate, so the best fit line can be selected. In this case, the equation, which results in the highest trip generation was selected. For both the AM and PM peak hours, there are equations based on more than 20 data
1 WSDOT project website, https://wsdot.wa.gov/construction-planning/search-projects/i-405renton-bellevue-widening-and-express-toll-lanes-project, accessed July 25, 2022. 2 Sound Transit website: https://www.soundtransit.org/system-expansion/i-405-brt/timeline-milestones, accessed July 25, 2022.
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points for each, so the equations were selected for the updated analysis (note that the R-squared values for both equations are 0.91).
No adjustments for transit mode of travel were assumed (e.g. 0% transit use). Comment 5: Page 4. Site Trip Generation (Commercial).
A. Although the commercial space is unknown, averaging multiple rates for the commercial space is not appropriate. Update to assume a singular use rate of either coffee shop or restaurant space as anticipated high internal capture is inconsistent with a retail space. Update to include pass-by rates consistent with proposed use.
B. Internal capture as presented has no basis. Update internal capture assumptions to be consistent with ITE’s Trip Generation Handbook methodology or remove from analysis. Note that internal capture reductions are applied to both proposed uses (commercial and residential and not just a singular use as presented in the analysis). Include detailed trip generation internal capture worksheets in updated analysis. Response: The small retail space on the site (about 1,500 sf) has no known tenant, and is not being
designed to accommodate restaurant functions. Therefore, rates and equations for a new land use specifically for small retail—Strip Retail Plaza (<40k) (Land Use 822)—were applied. For the strip retail use, there are fewer than 20 data points for both the daily and AM peak hour data. The daily
equation’s R-squared value is 0.96 and the standard deviation is less than 40% of the average rate, so the best fit line can be selected. In this case, the equation, which results in the highest trips generation was selected. For the AM peak hour, there is an equation, but the R-squared value is
0.54 and the standard deviation is about 14%. Therefore, as directed by ITE, the average rate was selected. For the PM peak hour, the equation based on more than 20 data points was selected as directed in the Trip Generation Handbook. No adjustments for internal trips between this use and the residential use were assumed, and no reductions for transit were applied. Comment 6: Page 5. Table 2. Trip Generation. Update table per above comments. Response: Table 2 has been updated per the above comments.
Comment 7: Page 6. Traffic Volumes.
A. The park-and-ride lot is noted on page 1 to be constructed “likely on the east side of I-405”.
Update analysis at all study intersections accordingly. Currently the narrative indicates the trips were re-assigned assuming the park- and-ride lot west of I-405, but the volumes don’t appear to support that, nor can we track the work.
B. Provide additional volume figures including the unadjusted volumes per the WSDOT’s analysis and show a figure illustrating the shifts so we can review the future volumes appropriately.
C. Provide a trip distribution and assignment figure, and discussion on the assumptions and why they are consistent or not consistent with the I-405 analysis. Response: The Sound Transit Board voted to defer a new 200-space park-and-ride lot until 2034 as part of its funding realignment process.3 Originally, the park-and-ride lot had been contemplated to
3 Sound Transit news release, September 2021. https://www.soundtransit.org/get-to-know-us/news-events/news-releases/sound-transit-board-selects-stride-brt-projects-to-be
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be located on the Kennydale Gateway site, but that is no longer proposed, and an alternative site has not yet been selected.
The Revised TIA updates WSDOT’s year 2025 traffic volumes to first subtract the trips that had previously been assumed for the site. The proposed project’s trips were then added. The park-and-ride trips are no longer assumed to be relocated in the 2025 traffic volumes since it has been deferred until 2034.
A new project trip distribution and assignment figure has been provided in the Revised TIA, and the Appendices include the original WSDOT volumes as well as the adjustments assumed to remove the site trips. The updated year-2025-with-Kennydale-Gateway-project analysis shows that all intersections are forecast to operate at LOS B or better. WSDOT also evaluated year 2045 conditions and the
interchange intersections are expected to continue operating at acceptable levels of service. Comment 8: Page 7. Figure 3. AM Peak Hour Traffic Volumes. Remove ‘X’ volume movements at the Seahawk Way intersection. Or define what is meant my denoting an ‘X’ on the figure.
Response: The “X” meant that the movement would be prohibited. The arrows have been removed from the revised figures. Comment 9: Pages 7 and 8. Figures 3 and 4.
A. Assignment as illustrated at the driveway in the figures suggests less than 5 percent of trips
to/from the south along Lake Washington Boulevard N. Based on a review of the assignment at the driveways in the WSDOT study, the distribution was approximately 15-20% to/from the south along Lake Washington Boulevard N. Provide support for difference from previous study or update analysis to be consistent with WSDOT study.
B. Update assignment to include both driveways if appropriate (see comment 2). Response: WSDOT did not provide detail about what specific land uses, other than a 200-space park-and-ride lot, that it had assumed would occupy the Kennydale Gateway site. At the time of WSDOT’s analysis, the site had been occupied by the Pan Abode industrial use—an employment-intensive land use. A park-and-ride and an employment center would have had more trips destined into the residential areas south of the site and accessed from Lake Washington Boulevard. The now-proposed Kennydale Gateway project is almost entirely residential, and it is unlikely to generate many trips to or from other residential areas located to the south. Therefore, the 5% of the trips assumed to use Lake Washington Boulevard south of the site is reasonable.
Comment 10: Page 8. Figure 4. Double check rounding as not all project trips are reflected in the assignment at the driveway.
Response: The volumes originally used for the analysis were from WSDOT’s Sidra models, and were apparently not balanced, and did not exactly match between intersections. The Revised analysis used the volumes from the I-405 Renton to Bellevue – NE 44th Street Intersection Control Analysis Report,4 which did balance the volumes. Adjusted volumes were checked to ensure they are balanced.
4 WSDOT, July 2018.
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Comment 11: Page 9. Table 3. Double check assumed volumes at site per WSDOT study. Per review of Figure A4 in the WSDOT study, there are 321 (166/155) AM peak hour trips and 323 (173/140) PM peak
hour trips. Confirm and update table as appropriate. Response: The original analysis utilized output from WSDOT’s Sidra models, which slightly differ from the values in the I-405 Renton to Bellevue – NE 44th Street Intersection Control Analysis Report (likely because Sidra does not accept “0” values for a movement). The values have been updated to match those in the Intersection Control Analysis Report. Note that the PM peak hour
volumes listed in the comment are incorrect; WSDOT’s report shows 150 trips entering and 173 trips exiting the site. Even with the trip generation revisions described above, the site would still generate fewer trips than WSDOT had assumed in all of its analysis (159 fewer trips during the AM peak hour and 153 fewer trips during the PM peak hour). Comment 12: Page 9. LOS Standard. Per WSDOT’s LOS Map, this section of I-405 suggests a LOS D standard. Update to assume LOS D.
Response: The text was revised to denote the referenced map standard. Comment 13: Page 10. Table 4.
A. Include v/c ratios for all roundabout controlled intersections. See WSDOT Sidra
protocol and confirm all parameters assumed are consistent.
B. Review operations using sidra corridor analysis to ensure closely spaced roundabouts and proximity to the proposed roundabout for the site access is not an impact to the adjacent interchange.
Response: The analysis was performed using the Sidra files provided by the WSDOT project team. No changes to WSDOT’s assumed operating parameters or v/c ratios were made. The roundabout intersections were evaluated using the Sidra 9 software’s Network analysis module and reporting methodology. The SIDRA analyses reflect model coding parameters established in the
WSDOT Sidra Policy Settings,5 and no changes to WSDOT’s assumed operating parameters or v/c ratios were made. software’s Network analysis module and reporting methodology. The results from the analysis are consistent with those reported in the WSDOT’s I-405 Renton to Bellevue –
NE 44th Street Intersection Control Analysis Report for the revised roundabouts. Comment 14: Page 10. Operational Analysis.
A. Include a queueing analysis at all study intersections using sidra corridor analysis.
B. With updates, please also include the requested study intersection included in the response to
comments.
C. Provide LOS worksheets and roundabout layouts. Note that following the submittal of
LOS worksheets, additional review of analysis parameters will be reviewed.
Response: This comment requests unreasonable and unnecessary analysis of intersections that are part of an interchange designed and evaluated by WSDOT and that is currently under construction. There is nothing related to the Kennydale Gateway project that suggests the design is inadequate or that additional analysis is required. Sidra files for the Kennydale Gateway project were sent to the City of Renton as part of a prior review cycle. The exceptions were the calculations for the 5 WSDOT, https://wsdot.wa.gov/sites/default/files/2021-03/TrafficOps-WSDOTSidraPolicyAndSettings.pdf, accessed March 2022.
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roundabout at Lake Washington Blvd N / N 43rd Street that will be constructed by the project applicant. Queue analysis was performed for that location and are reported in the Revised TIA.
Comment 15: Page 10. Future Roundabout at Lake Washington Blvd N / N 43rd Street. Confirm findings on roundabout geometry/channelization at the site access with updated operations and trip generation. Response: The updated analysis confirms that a single-lane roundabout would operate at an acceptable level of service with little to no queuing Analysis sheets for this roundabout are attached
to the Revised TIA. MCH/tsm
Kennydale Gateway - Response to City Transportation-related Comments - Round 2 - FINAL 08-15-2022