21-104849_Limited Scope TIA_11-16-2021_v1 TENW
Transportation Engineering NorthWest
Transportation Planning | Design | Traffic Impact & Operations
PO Box 65254, Seattle, WA 98155 | Office (206) 361-7333
MEMORANDUM
DATE: November 12, 2021
TO: Soma Chattopadhyay, Traffic Review Engineer
City of Federal Way
FROM: Michael Read, PE, Principal
TENW
SUBJECT: Trip Generation for Redondo Heights TOD (Site C Only)
TENW Project No. 2020-199
This memorandum summarizes a preliminary trip generation analysis for the proposed Redondo Heights
TOD (Site C) project by Shelter Resources, which is being provided with the Transportation Concurrency
Application. This memo includes a project description, methodology used to derive the trip generation
estimate, a trip generation summary, and request for further traffic scoping information by the City of Federal
Way.
Project Description
The proposed development is located on the east side of SR 99 (Pacific Highway S) in Federal Way. The
proposed project is a development of vacant property south and west of the existing Silver Shadow
Apartment complex. This phase of the Redondo Heights TOD project (Site C) would include up to 72
residential apartment units and a 6,000 square-foot food bank. A preliminary site plan concept is provided
in Attachment A.
Vehicle access to/from the site would continue at the existing access driveway to the Silver Shadow
Apartments and a new site access driveway approximately 324 feet to the south. In total, approximately 9
parking stalls would be provided on-site in surface and garage parking spaces as part of the project. As
part of the 5-Acre parcel proposed east of the Silver Shadows Apartment complex, an additional 11
surface parking stalls are proposed to serve the Site C development phase. As such, in total 110 parking
stalls would be provided to serve Site C.
Trip Generation Methodology
The weekday daily, AM peak hour, and PM peak hour trip generation estimates for the proposed Redondo
Heights TOD development were based on trip rates published in the Institute of Transportation Engineers
(ITE) Trip Generation Manual, 11th Edition, 2021. ITE Land Use Code (LUC) 221 was applied for the
multifamily housing adjacent to transit.
Given the site would be adjacent to the Redondo Heights Park-And-Ride and high frequency transit service it
provides as well as within walking distance of the future S 272nd Street Link light rail station, trip generation
rates published by ITE were applied for transit accessibility.
Trip Generation for Redondo Heights TOD (Site C Only)
TENW November 11, 2021
Page 2
Trip Generation Summary
Based on the detailed trip generation methodology described in the previous section, Table 1 summarizes
the weekday trip generation. As shown in Table 1, the project is estimated to generate a net increase of
approximately 648 daily vehicular trips, with 31 trips occurring during the AM peak hour and 47 trips in
the PM peak hour. Detailed trip generation calculations are provided in Attachment B.
Table 1
Redondo Heights TOD – Trip Generation Summary
Time Period In Out Total
Weekday Daily 324 324 648
Weekday AM Peak Hour 18 13 31
Weekday PM Peak Hour 22 25 47
Based upon the cumulative trip generation, a full Transportation Impact Analysis per City of Federal Way is
not required. A driveway operational analysis at full buildout is described below.
Site Access
Vehicular access to/from the proposed Redondo Heights TOD site would be provided via the existing right-
in, right-out only access driveway to the Silver Shadow Apartments (i.e. Site Access North) onto SR 99 as
well as a new secondary driveway to access Site C. The existing Site Access North would continue to
serve the Silver Shadow Apartments as well as provide access to the 5-Acre site as well as Site C.
Table 12 summarizes the weekday PM peak hour LOS analysis results at the two site access driveway
locations. As shown, the individual movements at the stop-controlled site access driveway currently operate
at LOS B with a volume-to-capacity (V/C) ratio under 0.2 during the PM peak hours with or without the
project in 2023 without any vehicle queuing forecast (1 vehicle or less). Detailed LOS summary worksheets
are included in Attachment C as well as full traffic forecasts/driveway assignments.
Table 1: Project Site Access LOS analysis – PM Peak Hour LOS Summary
2023 Without Project
(No Action)
2023 With Project
(Phase 1 – 5-Acre)
2023 With Project
(Phase 2 – Site C)
Study Intersection LOS Delay
(sec)
V/C
Ratio LOS Delay
(sec)
V/C
Ratio LOS Delay
(sec)
V/C
Ratio
PM PEAK HOUR
Stop-Controlled Intersections:
A. Site Access North (Existing)
Westbound Right-Turn B 11.3 0.04 B 11.7 0.08 B 12.6 0.15
B. Site Access South (Proposed)
Westbound Right-Turn - - - - - - B 12.1 0.08
If you have any questions regarding the information presented in this memo, please call me at (206) 361-
7333 x 101 or mikeread@tenw.com.
ATTACHMENTS
Attachment A - Site Plan
VISITOR PARKING
VISITOR PARKIN
G
PROJECT NUMBER 01DRAWING ISSUE LOG
Approval stamp
Site:Redondo Heights2100638
NOT FOR CONSTRUCTION LAND USE SUBMITTALSite C: 261 PaFiIiF +iJKZa\ SoXtK FeGeral Wa\ WA 8003Site C: FroQtaJe NeZ CoQstrXFtioQC
No.Description Date
C1.00
Attachment B - Trip Generation Calculations
ITE Trip Generation, 11th Edition, 2021Redondo Heights TOD ‐ Site CLU DailyProposedX Code Enter Exit Trips Enter Exit Trips Trips Daily Rate AM Rate PM RateMid‐Rise Apartment (Next to Transit)72 221 13 10 23 9 12 21 342 4.75 0.32 0.29Grocery6,000 850 10 7 17 27 27 54 563 93.84 2.86 8.96Pass‐By (36%)‐4‐2‐6‐10‐10‐19‐203Internal Retail to Site (15%)‐2‐1‐3‐4‐4‐8‐5418 13 31 22 25 47 648AM Peak PM PeakNet Change in Trip Generation with ProjectRedondo Heights TOD Site C ‐ Trip Gen Analysis .xlsx
Attachment C – Driveway LOS
HCM Unsignalized Intersection Capacity Analysis
6: Pacific Hwy (SR99) & Site Access S 12/07/2020
Redondo Heights TOD Synchro 10 Report
2023 With Project - PM Peak Hour - Full Buildout Page 12
Movement WBL WBR NBT NBR SBL SBT
Lane Configurations
Traffic Volume (veh/h) 0 40 1173 42 0 2586
Future Volume (Veh/h) 0 40 1173 42 0 2586
Sign Control Stop Free Free
Grade 0% 0% 0%
Peak Hour Factor 0.92 0.92 0.92 0.92 0.92 0.92
Hourly flow rate (vph) 0 43 1275 46 0 2811
Pedestrians 8
Lane Width (ft) 12.0
Walking Speed (ft/s) 3.5
Percent Blockage 1
Right turn flare (veh)
Median type None None
Median storage veh)
Upstream signal (ft)518
pX, platoon unblocked 0.47
vC, conflicting volume 2243 456 1329
vC1, stage 1 conf vol
vC2, stage 2 conf vol
vCu, unblocked vol 0 456 1329
tC, single (s) 6.8 6.9 4.1
tC, 2 stage (s)
tF (s) 3.5 3.3 2.2
p0 queue free % 100 92 100
cM capacity (veh/h) 480 553 517
Direction, Lane # WB 1 NB 1 NB 2 NB 3 SB 1 SB 2 SB 3
Volume Total 43 510 510 301 937 937 937
Volume Left 0 0 0 0 0 0 0
Volume Right 43 0 0 46 0 0 0
cSH 553 1700 1700 1700 1700 1700 1700
Volume to Capacity 0.08 0.30 0.30 0.18 0.55 0.55 0.55
Queue Length 95th (ft) 6 0 0 0 0 0 0
Control Delay (s) 12.1 0.0 0.0 0.0 0.0 0.0 0.0
Lane LOS B
Approach Delay (s) 12.1 0.0 0.0
Approach LOS B
Intersection Summary
Average Delay 0.1
Intersection Capacity Utilization 53.3% ICU Level of Service A
Analysis Period (min) 15