21-101715-Independent Transportation Impact Fee Calculation-06-28-2021-V1 TENW
Transportation Engineering NorthWest
Transportation Planning | Design | Traffic Impact & Operations
11400 SE 8th Street, Suite 200, Bellevue, WA 98004 | Office (425) 889-6747
MEMORANDUM
DATE: June 16, 2021
TO: Sarady Long, P.E.
City of Federal Way
FROM: Curtis Chin, P.E.
TENW
SUBJECT: Independent Transportation Impact Fee Calculation
Goddard School (#21-101715-00-UP)
TENW Project No. 2021-130
This memorandum documents the independent impact fee calculation for the proposed Goddard School
tenant improvement project located at 33310 1st Way South, Building B in Federal Way, Washington. The
proposed Goddard School project would convert approximately 14,511 square feet (SF) of office space
into a daycare. The proposed daycare would have a capacity for up to 176 students.
Background
Transportation impact fees for the proposed change in use were determined by the City of Federal Way
using the impact fee schedule for Day Care Center which is based on the square footage. Using square
footage as the independent variable to estimate impacts (trips) associated with the proposed Goddard School
may overestimate the project impacts during the PM peak hour. As an alternative, we are proposing to use
the student capacity of the school (176 students) as the basis for the impact fee analysis. Therefore, the
project applicant has requested that transportation impact fees for the project be determined by an
independent fee calculation rather than the impact fee schedule as allowed by Federal Way Revised Code
Section 19.91.070 (2). The analysis provided below shall serve as our independent fee calculation for
review and approval by the director.
Transportation Impact Fee Calculation
Transportation impact fees for the proposed Goddard School were calculated based on the following:
· Institute of Transportation Engineers (ITE) Trip Generation Manual 10th edition.
· City of Federal Way 2021 Transportation Impact Fee Schedule.
The CityÊs transportation impact fee schedule establishes the methodology used to determine transportation
impact fees which uses the following mathematical formula used to establish an impact fee rate.
Impact Fee Rate = Basic
Trip Rate X New Trip
Percent X Trip Length
Adjustment X
Impact Fee
Rate Per Trip
End
The trip generation rate for the proposed daycare used in the independent impact fee calculation was
determined based on the derived trip rate using students as the independent variable as described below.
Goddard School
Independent Transportation Impact Fee Calculation
TENW June 16, 2021
Page 2
Trip Generation Rate
The weekday PM peak trips used to derive a trip generation rate per student for the proposed Goddard School
was based on the ITE Trip Generation Manual 10th edition for Land Use Code (LUC) 565 Day Care Center.
The resulting PM peak hour trips and trip generation rate per student is shown in Table 1 below.
Table 1
Goddard School – PM Peak Trip Generation
Land Use
Student
Capacity
ITE Land
Use Code
PM Peak Hour
Trip Equation Trips
Trip Rate
(trips/student)
Goddard School
(daycare)
176
Students LUC 565 Ln(T) = 0.87 Ln(X) + 0.29 120 0.68
As shown in Table 1, the derived trip generation rate is 0.68 trips per student during the weekday PM peak
hour.
New Trip Percent and Trip Length Adjustment
The New Trip Percent and Trip Length Adjustment used in the independent fee calculation assumed the same
values included in the CityÊs Impact Fee Schedule for the Day Care Center land use as shown below:
· New Trip Percent = 75%
· Trip Length Adjustment = 0.65
Impact Fee Calculation
After applying the CityÊs impact fee formula using a trip generation rate of 0.68 trips/student, 75% new trips,
a trip length adjustment factor of 0.65, and the 2021 cost per PM peak hour trip end ($6,311.00 per trip)
results in an impact fee rate of $2,061.33 per student (see Table 2 below).
Table 2
Goddard School Traffic Impact Fee Rate
A B C D E = A x B x C x D
Trip Rate
(PM Trips/student)
Percent New
Trips
Trip Length
Factor
Cost Per
PM Trip End
(2021)
Transportation
Impact Fee Rate
0.68 75% 0.65 $6,311.00 $2,092.10 per
student
To determine the net transportation impact fee, credit for the former office space was determined using the
standard impact fee rate included in the impact fee schedule. The following Table 3 summarizes the net
transportation impact fee for the proposed Goddard School project.
Goddard School
Independent Transportation Impact Fee Calculation
TENW June 16, 2021
Page 3
Table 3
Goddard School Net Traffic Impact Fee
Land Use Units
2021 Transportation
Impact Fee Rate Impact Fee
Proposed Use
Daycare 176 Students $2,092.10 per student 1 $368,209.60
Less Existing Use
Office 14,511 SF $8.43 per SF -$122,327.73
Net Impact Fee = $245,881.87
1. Impact fee rate for daycare derived based on independent calculation.
Based on a student capacity of 176 students and credit for 14,511 SF of office, the net transportation impact
fee for the Goddard School is $245,881.87.
If you have any questions regarding the information presented in this memo, please call me at 425-250-
5003 or email at chin@tenw.com.
cc: Anuj Mittal, Tara LLC
Olivia Nisbet, TWIST Design
Kirk Callison, TWIST Design