HomeMy WebLinkAboutJ_Pascal&TIAcomments_200214_V1.pdf William Popp Associates Transportation Planners & Engineers
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14-400 Building Suite 206 14400 Bel-Red Road Bellevue, WA 98007
MEMORANDUM
TO: Andy Loos
FROM: Bill Popp, Sr., P.E.
DATE: February 14, 2020
SUBJECT: Responses to Transpogroup/Jon Pascal and City Comments on Cedar
River Apartments TIA dated October 21, 2019 and WSDOT
Comments on Cedar River Apartments TIA dated November 1, 2018
and a TIA Technical Supplement dated May 28, 2019
The Jon Pascal comments are from the 12/2/19 letter to Matt Herrera and the City and WSDOT comments
were appended to a 12/4/2019 email from Matt Herrera. The comments are included in boxes with
responses to each comment immediately following.
Jon Pascal’s 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.
The referenced plan and architectural sheets are being revised -- the gross floor area for the medical office
building (Phase 3) is 25,000 gsf, thus it will not be necessary to revise the analysis.
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.
The trip assignment figures for the project AM and PM peak hour trips show the project trips assigned
through the subject analysis intersections and identify the outlying distribution percentages in the text.
However, for consistency with the City’s guidelines, a new figure has been added as Figure 7a to the
February 2020 TIA to show the outlying area distribution percentages and accompanying project trip
assignment volumes.
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.
The pass-by trip estimates amounted to only 2 trips (1 in and 1 out) for the AM peak hour, and 6 trips (3 in
and 3 out) for the PM peak hour. The number of pass-by trips were so small that they were not included in
the LOS analyses as the changes would be miniscule and which should have been covered by a note to that
effect. However, since the analyses are being redone for a 60-minute simulation we have also updated the
project turn movements to include 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.
The Synchro worksheets represented the analysis volumes prior to the Sim Traffic update in response to
WSDOT 9/9/19 comments. The Sim Traffic analysis reflects the corrected volumes; the Synchro
worksheets have been replaced and reflect the latest volumes to match Figures 8b and 9b.
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.
By way of background, the City comments on the November 2018 TIA requested the analysis include the
effects of ramp meter impacts on intersection LOS estimates and the later WSDOT comments requested
queuing estimates using Sim Traffic. Thus the analyses necessarily transitioned from Synchro to a Sim
Traffic focus. Nonetheless, HCM/Synchro analyses were continued to plainly demonstrate that the Project
in its phased buildout will have little impact on intersection LOS & delay (the Synchro method avoids
complicating considerations of freeway congestion and ramp meter operations). This procedure was also
relevant for direct comparison with the intersection LOS values from WSDOT’s Transportation Discipline
Report for the I-405 ETL Project (WSDOT used HCM/Synchro).
The 0.90 was developed as a conservative value for Synchro to better replicate actual congestion using
queuing observations and results from Sim Traffic interim runs for estimates of delay to use as benchmarks.
The actual PHF’s at the four subject intersections range between 0.94 and 0.97. However, in the interest of
conforming to the WSDOT guidance (see below) and Pascal’s comment, the future conditions analyses in
the February 2020 TIA utilize the PHF of 1.0 for simulation and Synchro analyses.
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.
The Synchro Protocol directs the PHF basis for analysis of existing conditions be based on HCM which
means calculation from consecutive 15 minute counts during the peak hour. However, for analysis of future
conditions the Protocol specifies a PHF between 0.92 and 1.0 with the caveat that justification must be
provided if PHF other than 1.0 is used. Therefore a PHF of 1.0 is the de facto Synchro Protocol guidance
for future conditions.
The Sim Traffic Protocol provides a large table that contains various inputs including a volume growth
factor, but, as noted by Pascal, does not contain specific PHF guidance. That is because the Sim Traffic
methodology receives the PHF adjusted volume data from Synchro -- Sim Traffic software does not have
any input for PHF (other than anti-PHF). We conclude therefore that for future conditions using Sim
Traffic, the guidance is 1.0, unless justification is provided for an alternative value. The foregoing is
somewhat akin to a forum discussion as we agree that 1.0 should be used for both the Synchro and Sim
Traffic future condition runs.
Without PHF provided for the existing turning movement counts, the future PHF could be estimated based
on Table 19 from NCHRP Report 599.
The PHF values identified in NCHRP 599 report are generic by region of the country for use when the PHF
is not known. In our case PHF’s are known (15 minute counts are presented in the Appendix), but were
simply not discussed or applied in the analyses for reasons given above in the 0.90 discussion.
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.
While “commonly used 60-minute duration” does not suggest formal analysis policy guidance, 60 minute
intervals have been utilized for the February 2020 TIA. It should be noted that Sim Traffic reports the
maximum queue every 2 minutes thus the longer it runs the more likely it is extreme events will result,
since it is stochastic in construct. To address this we have, in addition to the maximum queue, presented the
average queue which is the average of the 2 minute maximum queues which we would argue are entirely
reasonable data for traffic impact assessment purposes.
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 Sim Traffic. The TIA should be updated to include this
additional scenario in the Sim Traffic 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.
The requested analysis has been conducted and the LOS is B, even with extensive queuing. However,
should there have been a LOS issue, the Project will still meet the definition of concurrency under RMC 4-
6-070 because WSDOT will complete the ETL project within six (6) years of building permit issuance for
this Project.
Page 38. SimTraffic Files. Please provide the actual SimTraffic files so the results can be reviewed more
closely.
These 2023 and 2029 with and without project, for AM and PM peak hours, will be submitted via email to
the City.
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.
This section of the report has been adjusted to include RMC parking supply requirements, bicycle parking,
as well as justification of the KC MF Residential Parking Calculator for estimated parking demand for the
residential portion of the project.
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.
The requested width has been added.
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.
The location of the access point has been corrected on page 49 to read 350 feet, which is the correct
distance as well as being consistent with page 45. However the portion of the review comment stating the
location “is where the 3-lane section of southbound SR 169 transitions to a 2-lane facility” is not correct.
The 3-lane section transitions to the 2-lane facility approximately 150 feet east of the new access driveway
thus the concern regarding merging may be misplaced.
Page 49. Secondary Site Access – Left-Turn Restriction. We are concerned about the proposed
mountable “porkchop” 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?
It is acknowledged that a mountable pork-chop concept will discourage left turns in or out but it will not
prevent all left turn movements, and this was intended. The mountable concept would allow for larger
trucks to use the island as part of the right-in right-out movement. A C-curb would prevent that and was
thus considered an undesirable application.
City Comments
9. City Transportation Comments – Please provide responses and corrections to the following comments
from the City’s Public Works Department – Transportation Division:
a. Traffic Impact Analysis (dated 11/01/18), page 15, I-405/SR 169 Interchange Improvements, the first
paragraph should be revised to read as follows:
“There are currently two interchange projects proposed at this location. The first involves a proposed short-
term enhancement with re-channelization of the southbound on-ramp to include two general purpose lanes
(the HOV lane will be removed). Use of the shoulder when the ramp is metered will still be allowed. Also
as part of this, the westbound approach would be modified (underneath I-405) to include two westbound left
turn lanes to the southbound ramp. This would involve re-channelization of the inside through lane to a
shared thru plus left turn lane. The signal already operates as a split phase and no timing changes are
required. This concept is expected to be completed in 2020 as it benefits to current traffic operations are
substantial.”
Noted and the narrative has been modified with some restructuring to separate the long range plan
discussion from the immediate project description. Also WSDOT states in their comments on the 11/1/18
TIA that the northbound ramp will also be modified to include an HOV by-pass lane, so this has been added
as well.
b. The preceding revised paragraph should be reflected in the Conclusions section of the TIA.
Noted and the narrative has been modified.
c. Traffic Impact Analysis Supplement ( dated 5/28/19) – the analysis (of which results are reflected in
Table 3 on page 6) should be revised to reflect the above revised paragraph. Footnote b in Table 3 should
be revised accordingly.
Noted and has been included as footnote b in Table 8 of the February 2020 TIA.
d. Regarding the results in the AM and PM peak hour for the SR 169/Sunset/ Bronson/I-405 SB On ramp in
Table 3, it is hard to believe that ramp metering will add 100 sec/veh over non-ramp metering (based on
results shown in Table 9 in the 11/01 TIA) with three general purpose lanes available during ramp metering.
Also, should LOS improve significantly without the HOV lane on the southbound ramp?
The ramp meter congestion was observed to spill back through the SR 169/Sunset Way/Bronson/I-405 SB
On-Ramp intersection. This in-turn increases the congestions for traffic entering the on-ramp (from the
north and from the east). The ramp spill back and ultimate congestion at the upstream signal is not realized
in the Synchro analysis, Table 3 of the 11/1/18 TIA. The subsequent simulation analysis 5/28/19 identifies
the ramp congestion and spill back through the upstream signal as well as the subsequent upstream analysis
intersections on SR 169, thus the results between the Synchro and Sim Traffic methods are significantly
different, even to the extent of 100 sec/veh.
WSDOT Comments
.
Duffy McColloch, Comment submitter
WSDOT NW Region (comments dated Sept 9, 2019)
Responses to WSDOT’s comments were previously addressed in the TIA dated October 21, 2019
and are summarized below.
TIA (November 1, 2018)
1. Pg. 8: Refer to the highlighted text below Table 1. Please quantify this statement or consider
deleting it.
The accident section has been modified. This statement revised to citing ITE recommended
practices.
2. Pg. 8: Please create a Table for crash severity (fatal/serious injury/no injury).
Done. Two additional tables were created. One for crash types, and the other crash severity.
3. Pg. 9 and Pg. 11, Figure 6: The data used is 9 years old and there has been significant
growth in the region since then. Please update with recent data within the last three years to
determine peak periods for analysis.
Figure 6 has been removed. The intent of that figure was not to show recent volumes but simply
when peak periods occurred. Peak periods for AM and PM analyses were actually derived from year
2017 2-hour turning movement counts.
4. Figure 5a and 5b: Please include the AM and PM Peak periods. This should be determined
using the most recent counts.
Peak hour periods have been noted on both figures as being 1-hour within the 2-hour count windows.
5. Pg. 13 and Pg. 14: Refer to the highlighted text below Table 4 and 5. Please quantify this
statement or consider deleting it.
The text has been revised.
6. Pg. 13: Please include the queuing for the intersections using SimTraffic.
Queuing results based on Sim Traffic findings have been included.
7. Pg. 14: Refer to the highlighted text. Please quantify and include the LOS thresholds. Per
the Developer Services Manual, the LOS threshold for HSS is LOS D for Urban Areas and
LOS C for Rural Areas.
Included.
8. Pg. 15: The northbound I-405 on-ramp will also be modified by the I-405 Renton to Bellevue
project with a single general purpose metered lane and an HOV metered shoulder.
Noted and future analyses updated to reflect this. The analysis assumes 10% HOV by-pass for the
northbound ramp
9. Pg. 16: Please include analysis and figures for future AM and PM Peak without project
traffic volumes for opening year/full build out (2023) and a six year horizon year (2029). The
2029 horizon year was selected since this is five years after the completion of the Renton to
Bellevue Widening and Express Toll Lanes. These figures are necessary to understand the
difference in operations between no build condition and with project condition. There needs
to be an analysis of the horizon year to understand project impacts on ramp terminal and
intersection operation beyond the opening year. Refer to Design Manual Chapter 1103.02.
The updated report includes the requested AM and PM with and without project figures for both
2023 and 2029, and analysis.
10. Pg. 17: For the project trip generation, please consolidate and use LUC 820 - Shopping
Center. WSDOT Region Traffic accepts its use for mixed-use retail for TIAs. LUC 920 also
has only one sample and local data collection would be required. Refer to the Trip
Generation Handbook 3rd Edition, Chapter 9.3.
The trip generation for the commercial/retail component in Phase 2 Building B was updated such that
it is based on LUC 820.
11. Pg. 17: How was this pass-by trip rate derived? Per the Trip Generation Handbook 3rd
Edition, Chapter 10.3 states that pass by trip estimates should be derived from Appendix E
or collecting and using pertinent local data. In addition, by using LUC 820, there is already
an average pass-by trip calculated in Appendix E.
The retail use trip generation was updated to LUC 820. The pass-by component is now based on
LUC 820.
12. Pg. 18, Table 6: Were diverted trips actually used? If not, please delete. Per the Trip
Generation Handbook 3rd Edition, Chapter 10.4.2, diverted trips should only be used on
certain occasions.
Diverted trips were not actually used. The original table assumed diverted trips were part of the
primary trips, ie., non-pass-by trips are primary and diverted. However, as noted in #10 and #11
above, the subsequent analysis revised the trip generation and pass-by rates to those contained in
LUC 820. The revision now includes more types of retail trips including pass-by.
13. Pg. 19: Volumes and traffic are only analyzed through 2023. There should be a 2029
horizon year included and analyzed. Please see Comment 9.
The February 2020 TIA includes a 2029 analysis section.
14. Pg. 22 Table 7: Please include a queuing analysis using SimTraffic of without project and
with project conditions in the opening and horizon year.
The February 2020 TIA includes queuing for with and without project for AM and PM peak hours
for 2023 and 2029 conditions.
15. Pg. 31: Please consider restricting the access to right-in right-out. Westbound left turn
movements will have to cross three lanes to enter the driveway. There is also a controlled
access at Cedar River Park Dr.
The February 2020 TIA assumes this driveway as right-in and right-out only.
16. Pg. 31: The proposed development will generate new trips that will head to westbound SR
169 from Cedar River Park Dr. The green time for SR 169 was also reduced in the
submitted Synchro analysis to accommodate the new vehicle trips from Cedar River Park
Dr. This results to a reduced westbound SR 169 vehicle throughput. Westbound SR 169
transitions from two lanes to three lanes before the Cedar River Park Dr intersection. The
SimTraffic queuing analysis for opening year and horizon year were not included and is
required to review SR 169 operations. Without this information, as part of mitigation, please
extend the outside westbound lane 600 feet to account for the additional project trips that
are displacing SR 169 traffic and to mitigate for the reduction in mainline cycle length.
Please refer to comments above regarding inclusion of queuing analysis in February 2020 TIA.
TIA Supplement Report (May 28, 2019)
Note: This report along with the original November 2018 TIA had been combined into one larger report
(October 21, 2019) that includes the original Synchro analyses plus the more applicable SimTraffic
analyses.
17. Pg. 1: Please quantify instead of using “guestimate.” In Section 4, there were approximate
meter rates from observations.
The wording has been revised.
18. Pg. 2: Please updated to “without.” Refer to PDF.
Corrected, thanks.
19. Pg. 4, Table 2 and Pg. 6, Table 3: Please provide a queuing analysis using SimTraffic.
February 2020 TIA includes queuing for with and without project for AM and PM peak hours for
2023 and 2029 conditions.
20. Pg. 5: How were the ramp meters included in the model? Please send the
Synchro/SimTraffic model for review.
For all ramp meter conditions with 6 or more seconds, the ramp meters were modeled using 2-phase
signal with short cycle length and a dummy side street, and for the ramp a stop sign was located just
downstream of the signal such that only one car would pass through the meter during each cycle. A
stop sign was observed in Sim Traffic to have a release rate of 4 seconds. This was used to simulate
conditions for a 4 second meter.
The requested Synchro files (2023 and 2029) will be sent as attachments with the February 2020 TIA
for distribution to WSDOT and the City’s consultant,