20-104353_Limited Scope TIA_10-22-2021_v2 TENW
Transportation Engineering NorthWest
Transportation Planning | Design | Traffic Impact & Operations
PO Box 65254, Seattle, WA 98155 | Office (206) 361-7333
MEMORANDUM
DATE: October 22, 2021
TO: Soma Chattopadhyay, Traffic Review Engineer
City of Federal Way
FROM: Michael Read, PE, Principal
TENW
SUBJECT: Trip Generation for Redondo Heights TOD (5-Acre Site)
TENW Project No. 2020-199
This memorandum summarizes a preliminary trip generation analysis for the proposed Redondo Heights
TOD (5-Acre Site) 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 immediately east of the existing Silver Shadow
Apartment complex. At completion, the proposed project would include up to 130 residential apartment
units. 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 with a secondary fire/emergency vehicle only driveway onto S 276th Street that serves the
adjacent Redondo Heights Park-And-Ride. In total, approximately 205 parking stalls would be provided
on-site in surface parking spaces as part of the project, of which 192 would be dedicated to the 30 units,
2 would be constructed to serve as a loss for parking within the existing Silver Shadows complex, and 11
would be developed to serve a future project phase.
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.
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 (5-Acre Site)
TENW October 22, 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 618 daily vehicular trips, with 42 trips occurring during the AM peak hour and 38 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 309 3096 618
Weekday AM Peak Hour 24 18 42
Weekday PM Peak Hour 16 22 38
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.
The existing Site Access North would continue to serve the Silver Shadow Apartments as well as provide
access to the 5-Acre site.
Table 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.
Table 2
Project Site Access LOS analysis – PM Peak Hour LOS Summary
2023 Without Project
(No Action)
2023 With Project
(Phase 1 – 5-Acre)
Study Intersection 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
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
C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C CCCC
R
R
R All rights reserved. Materials may not be reproduced in any form without permission of Bumgardner. If scale is not 1" then this drawing has been reduced or enlarged.11/2/2020 4:33:36 PM
No.Description Date
1601 5th Avenue, Suite 1600
Seattle, WA 98101
206.622.5822
www.kpff.com
R
Call 811
two business days
before you dig
1 Land Use Submittal 11/05/2020
2 Land Use 05/20/2021
Correction 1
3 Land Use 10/18/2021
Correction 2
C1.00
10/19/2021
Attachment B - Trip Generation Calculations
Multifamily Housing (Mid-Rise)
Close to Rail Transit (221)
Vehicle Trip Ends vs: Dwelling Units
On a: Weekday
Setting/Location: General Urban/Suburban
Number of Studies: 2
Avg. Num. of Dwelling Units: 393
Directional Distribution: 50% entering, 50% exiting
Vehicle Trip Generation per Dwelling Unit
Average Rate Range of Rates Standard Deviation
4.75 4.72 - 4.79 *
Data Plot and Equation Caution – Small Sample Size
T = Trip EndsX = Number of Dwelling Units
Study Site Average Rate
Fitted Curve Equation: Not Given R²= ****
Trip Gen Manual,11th Edition Institute of Transportation Engineers
0 100 200 300 400 500
0
500
1,000
1,500
2,000
2,500
130
618
1 of 1 10/22/2021, 1:56 PM
Multifamily Housing (Mid-Rise)
Close to Rail Transit (221)
Vehicle Trip Ends vs: Dwelling Units
On a: Weekday,
Peak Hour of Adjacent Street Traffic,
One Hour Between 4 and 6 p.m.
Setting/Location: General Urban/Suburban
Number of Studies: 7
Avg. Num. of Dwelling Units: 139
Directional Distribution: 43% entering, 57% exiting
Vehicle Trip Generation per Dwelling Unit
Average Rate Range of Rates Standard Deviation
0.29 0.16 - 0.35 0.05
Data Plot and Equation
T = Trip EndsX = Number of Dwelling Units
Study Site Average RateFitted Curve
Fitted Curve Equation: T = 0.29(X) - 0.09 R²= 0.89
Trip Gen Manual,11th Edition Institute of Transportation Engineers
0 50 100 150 200 250 300
0
20
40
60
130
38
38
1 of 1 10/22/2021, 1:57 PM
Multifamily Housing (Mid-Rise)
Close to Rail Transit (221)
Vehicle Trip Ends vs: Dwelling Units
On a: Weekday,
Peak Hour of Adjacent Street Traffic,
One Hour Between 7 and 9 a.m.
Setting/Location: General Urban/Suburban
Number of Studies: 7
Avg. Num. of Dwelling Units: 139
Directional Distribution: 56% entering, 44% exiting
Vehicle Trip Generation per Dwelling Unit
Average Rate Range of Rates Standard Deviation
0.32 0.18 - 0.45 0.09
Data Plot and Equation
T = Trip EndsX = Number of Dwelling Units
Study Site Average RateFitted Curve
Fitted Curve Equation: T = 0.31(X) + 1.06 R²= 0.74
Trip Gen Manual,11th Edition Institute of Transportation Engineers
0 50 100 150 200 250 300
0
20
40
60
80
130
42
41
1 of 1 10/22/2021, 1:56 PM
Attachment C – Driveway LOS
HCM Unsignalized Intersection Capacity Analysis
5: Pacific Hwy (SR99) & Site Access N 12/07/2020
Redondo Heights TOD Synchro 10 Report
2023 With Project - PM Peak Hour - Phase 1 Page 10
Movement WBL WBR NBT NBR SBL SBT
Lane Configurations
Traffic Volume (veh/h) 0 44 1080 62 0 2512
Future Volume (Veh/h) 0 44 1080 62 0 2512
Sign Control Stop Free Free
Grade 0% 0% 0%
Peak Hour Factor 0.95 0.95 0.95 0.95 0.95 0.95
Hourly flow rate (vph) 0 46 1137 65 0 2644
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)212
pX, platoon unblocked 0.50
vC, conflicting volume 2059 420 1210
vC1, stage 1 conf vol
vC2, stage 2 conf vol
vCu, unblocked vol 0 420 1210
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) 514 584 574
Direction, Lane # WB 1 NB 1 NB 2 NB 3 SB 1 SB 2 SB 3
Volume Total 46 455 455 292 881 881 881
Volume Left 0 0 0 0 0 0 0
Volume Right 46 0 0 65 0 0 0
cSH 584 1700 1700 1700 1700 1700 1700
Volume to Capacity 0.08 0.27 0.27 0.17 0.52 0.52 0.52
Queue Length 95th (ft) 6 0 0 0 0 0 0
Control Delay (s) 11.7 0.0 0.0 0.0 0.0 0.0 0.0
Lane LOS B
Approach Delay (s) 11.7 0.0 0.0
Approach LOS B
Intersection Summary
Average Delay 0.1
Intersection Capacity Utilization 51.9% ICU Level of Service A
Analysis Period (min) 15