2010-09-30 HEX# 10-007 Exhibit D0 0 RON THAIFIFOC CONSUL 7AN-13
TRAFFIC ENGINEERING • TRANSPORTATION PLANNING
2802 WETMORE AVE. - SUITE 220 - EVERETT, WA 98201 - PH: t425j 339-8266 - FAX: (425) 258-29221
June 3, 2010
EXM1PIT 'b
PAGE__i_..GF
Mr. Sarady Long, Traffic Division RESUBMITTED
City of Federal Way
33325 8thAvenue S .IUR 4 4 2010
Federal Way, WA 98003
CITY OF FEDERAL WAY
Re: St Luke's Lutheran Church Classroom Addition in Federal WWILDING DEPT.
Comment Resolution Memorandum — GTC #09-138
Dear Mr. Long:
Gibson Traffic Consultants (GTC) has been retained to provide a comment resolution
memorandum for the proposed St Luke's Lutheran Church Classroom Addition. This comment
resolution report is in response to the City of Federal Way comments. The comment resolution is
based on the traffic impact analysis completed by GTC dated February -4, 2010 and the
Additional Information Requested memo from the City of Federal Way dated April 9, 2010.
Comment #1
Planning Division: Please explain the discrepancy between the report and the site plan or
number each parking stall showing which parking stalls were included in the "on -site" parking
stall count.
The site plan has gone through many revisions, the final plan now shows a total of 220 parking
stalls (164 parking stalls around church buildings) and parking stalls that are located in the shared
Park & Ride lot (56 parking stalls) on the east side of 6 b Avenue S. The count of 220 does not
include any of the approximately 3 5 parking stalls located along 6th Avenue S in the site vicinity.
Comment #2
Traffic Division: The proposed joint access driveway should be a minimum of 30.' wide
and may increase up to 40' wide for a three -lane two-way driveway. To allow safe and
efficient access, staff recommends a 40' wide three -lane two-way driveway.
Based on the traffic impact analysis of the combined driveway as a two-lane two-way driveway
the intersection operates at acceptable LOS D with the 95th percentile queue length of 79 feet
(approximately 4 vehicles). The 79 feet does not impact the outbound drive aisles of the Mission
COUNTS/SURVEYS•- SITE IMPACTS LOS ANALYSIS - EIS - HEARINGS- SAFETY - SIGNALS PARKING
Mr. S arady Long
June 3, 2010
Page 2
EXHIPM
PACE .OF-2-
Korean Church (110 feet south of South 312th Street) or St Luke's Lutheran Church (120 feet
south of South 312th Street). The combined driveway will provide safety enhancements over,the:
current two driveways by eliminating conflicting movements. The combined driveway will also
align with 5th Avenue S, which will remove the existing off -set with the St Luke's driveway. If
the driveway was to be constructed with 40 feet of width the driveway would come within 8 feet
of the proposed building.
Comment #3
Traffic Division: Use the 85`h percentile attendance in -lieu of the average attendance of
318 parishioners to calculate parking demand.•
Per the Institute of Traffic Engineers (ITE) Parking Generation, 3rd Edition, the definition of 85th
percentile is the point at which 85 percent of the values fall at or below and 15 percent of the
values are above it. Because many of the data sets for individual land uses are comprised of
relatively few data points, the percentile value can represent an interpolation between -actual
values. These numbers are not intended to recommend a policy about the levels of parking that
should be supplied. They are provided solely as qualitative references for the analyst. Nowhere
within the City of Federal Way, Guidelines For The Preparation of Parking Studies/Survey
Analysis and Reports, does it call out that the 85th percentile attendance or 850 percentile
demand should be utilized.
ITE Land Use Code 560, church, with the independent variable attendees has 16 study sites, each
site per ITE procedures identified the number of attendees at the time when the parking counts
were conducted and the average for the 16 sites is 410 attendees, an 85"' percentile attendance is
not provided. The average of the two Sunday's that GTC conducted parking counts was 320
attendees, this is consistent with the average Sunday attendance for the entire .2009 year of 318
attendees. There is no precedent to use an 85th percentile attendance in addition to the 85th
percentile parking demand to calculate the parking demand of the church. In addition, it is not
possible to determine the 85th percentile attendance from the I'I`E supplied data.
If the City of Federal Way insists on requiring the 85th percentile attendance for 2009, then they
should also accept the O' percentile weighted average of the two GTC parking counts with that
of the 16 ITE data points. Doing this would show that the required 85th percentile parking
demand based on the two GTC parking counts and 16 1TE studies would be 0.61 parking
demand/attendee. The Sunday 85th percentile attendance for 2009 is 357 attendees; therefore, the
85th percentile peak parking demand would be 218 parking stalls. This is inline with using the
average attendance and the 85t�' percentile parking demand of ITE averaged with the two GTC
parking counts with a peak parking demand of 219 parking stalls.
RAN"FOIC"
Mr. Sarady Long
June 3, 2010
Page 3
Continent #4
Traffic Division: Off -site parking along 6rh Avenue South should not be counted to
accommodate parking overflow as these spaces may be used by others. Please minimize
impact to surround residential neighborhood.
Per the site plan showing 220 parking stalls there is sufficient parking on -site to satisfy the
parking demand of the church based on the accepted Institute of Traffic Engineers (ZTE)
engineering practice of using the average attendance numbers to determine the 85`h percentile
parking demand of 219. The attendance numbers are not anticipated to increase with the
classroom addition.
Continent #4
Traffic Division: From the 2009 attendance record, it seems that additional parking will
be needed for a couple of special events each year. Please identify plans to accommodate
these events and also parking overflow. .
During high demand events such as Easter and Christmas additional parking is provided in the
-southwest corner of the site in the dirt/gravel lot. This area provides area for approximately 100
vehicles for special events. Also, during these high demand events the church has an organized
event parking management plan with four to five people in orange vests -to control/direct traffic
on -site. On a typical Sunday they have one individual that directs traffic at the church accesses
on 6t' Avenue S.
GTC trusts this comment resolutions resolves the City comments regarding the February 4, 2010
traffic study conducted by GTC for the proposed St Luke's Lutheran Church Classroom
Addition.
Sincerely,
GIBSON TRAFFIC -CONSULTANTS, INC.
Matthew J. Palmer, PE
Traffic Engineer
Attachments
XC: Robert Rowan, BPH Architects
RR'A"AF OIC"
I
Laud Use: 560
Church EXPIMIT
Average Peak Period Parking Demand vs: Attendees
On a: Sunday
$fatistic
xt? aii4 � icfd ! t7aarid
Peak Period
9:00 anA2:00 p.m.
Number of Study Sites'
16
Average Size of Study Sites
410 attendees
Avera a Peak Period Parldng Demand
0.44 vehicles Rer attendee
Standard Deviation
0.16
Coefficient of Variation
37%
Range
0.12-0.63 vehicles per attendee
85th Percentile
0.60 vehicles per attendee
33rd Percentile
0.41 vehicles per attendee
♦e �
40P = 0.49x - 8
3
2,000
1
+ Actual Data Points Fitted Curve - - - - Average Rate
Institute of Transportation Engineers 138 Parking Generation, 3rd Edition
AN!
l; -
R�-;� EXPIPlT
M �
PAGE... �G,._._
Fl;
rl
Gen-erat.'Ion
E;
n. or
,'
:Second .E.ditio.n t.
=f=
r• • .An -ITE :=Reco mended Practice
� ;
i tter 4
June.2004 '
= Institute of 7ransportatlon.�ngineers '_
Generation. Sources will be cited,
but the identity ofspecific sites will
be kept confidential.
Combinin,M g Trip
Genera-tion and
Local Data .
If the Trip Generation database for a
particular land use is relatively
small (e.g., nine or fewer sites), the
local.community should consider
merge the national and local
databases to create. a consolidat-
ed. trip generation rate. It is rec-
ommended that this merging of the
data sets take place if the local and
...national --average rates are rea-
sonably close (e.g., within 15
percent of each other). The
merging of the two. databases under
those circumstances should
improve the statistical strength of
the overall database for the pardcu-
lar land use.
If the local and national 'rates are
substantially different, refer to
Section 4.5 for guidance on the
establishment of a local rate.
The following procedure demon-
strates the proper steps for merging
the local and national databases.
IN
EXFTPlT_L�
PAGE._L_Gt_2
This procedure can be used for any
land use, time period and indepen-
dent variable for which weighted
average trip rates, average size of
the independent variables and
number of studies are provided in
Trip Generation.
Note: This method of combining
data sets does not allow precise
calculation of the standard devia-
tion or of a revised regression
equation because of the unavailabil-
ity of the exact data points in the
ITE national database.
22 ITE ■ Trip Generation Handbook, 2nd Edition Chapter 4
EXHI P IT L_
PAGE...Lo
` h' basice uati n;ioi;.ca e-ul-aEn a. eoinbined Nvei cited av ra�ii,'tri .. 'eneratiQn rat
(1)• .combinecl ,weighted . trap -ends .(ITE) `. trip ends (local)',
. : �uaverage trip rats:..
�� ;; .: ,;,: y.• q�.�.} .. .. j6der�.endent�..vai'aL;i�=. ui7il :: {T[wj + independent Maria :ale uilit5 .(lQ>u �`.,
Ti e p 'arnetars.'' ' tnp:snds {IT'E;" aril "�'. inde;�enden' variable (I can be calculated tom stats1: pro-
vided in Trip Cenera!iw..
.. � .. ;
p ends �1TE)-= ..{weightett averag .rip ratb] x',aveeag� v31ur •�f inclap�n Sa,ni vari hie; unit} x •p i sber �f'
7 (udins}, =m'
Indepeh'demwirlable units (I f E) - {avarag P,.va;ue o' i!1C:•':;i i`•C?r;t vat i�l.`)1i] Lmlf) :Y. lrll mber;)f Stud1CS
ale pa,arneta s " :independent variable units'(Iecai)": atrio-ends ' triqends (lo IJ"' should .be a: alia le floor `net Icwal -
i'
database.
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eeI da '.iri ;.E,nds'' GFA .00
- . r�.:f` _ - _ ' �v: ti y ir: �- - �:.'i"-S.Cr. �� •� - . r�_��L7, - _ ,�7 � �.=•.-< y :'iik=i'i�;':i�r st�"-'sw} :tins" . ;S S'•i,,:t.'.w
t�''� �,.�, �^'�.r?ss, — �, I i�;1f'�� �.��, ��id1�:s i�'jir§i;`'ly�j :j �. - ,:��, , 41K•r .:.�,!
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iir.:n fir,
{ fE r ,,_,,
or:.1 u l fW ME
nul
Frarri'I'ocal.bata:,``' •.=>"d�7e"ricient .r�araGle` tiiifs l•{lac[j f` 48a';£'i :a
R
Frorn local bata: Y trip ends ilocalj.._-MrooO
Cpplvirtg equabr. combined -weighted average.trip rate ;
(78,73P F ?5 0�17}L," ..81�0 1 3 }: 5c7.?
f• ,The updated weigxjltcd-average_ me is 50.-2 Cveelca y tv75 p[l !,()Of) .Sil. ft. C]. g.CC75i t.7[7y,
L.•j. Yl.. _ ...5,,
Trip Generation Handbook, 2nd Edition Chapter 4 IN ITE 23
St Luke's Lutheran Church
GTC #09-138
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PAGE,LC,F.4..
ITE:
85th percentile 0.60
Average Size of Study Site 410
Number of Studies 16
sum parking demand 3936
sum independent variable 6560
Local:
indepe-ndent units total 640
parking demand 467
Combined 85th Percentile:
0.61
85th2009 Attendees 357
85th %-tile Parking Demand 218