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HomeMy WebLinkAboutTraffic Impact Analysis and Supplement ReportWILSON PARK PLAT "(°tRento,
TRAFFIC IMPACT ANALYSIS nrrr9 Division
CITY OF RENTON
200,c
ftce#veo
Prepared for
Mr. Robert Wilson
21703601h St. E.
Lake Tapps, WA 98391
Prepared by
IVOR THWES T
TPAFFlc EXPERTS
11410 NE 124"! St., #590
Kirkland, Washington 98034
Telephone: 425.522.4118
Fax: 425.522.4311
June 23, 2009
TIS o ' e 5
e,-6 tA d p
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V
EXHIBIT 12,;
rraffZ&( iYDRTh FT TRAFFIC EXPERTS
1141011' 1eyth SI., #590 KirWa.gd, VA 95034
Phom. 425.522.41 18 Fax 425.522.4811
June 23, 2009
Mr. Robert Wilson
21703 60" St_ E.
Lake Tapps, WA 98391
Re: Wilson Park Short Plat - City of Renton
Traffic Impact Analysis
Dear Mr. Wilson:
We are pleased to present this traffic impact analysis report for the proposed 14
lot Wilson Park Residential short plat located at the 720 S. 55"' St. in the City of Renton.
The scope of this analysis is based upon the preliminary plat site plan, the Ci of
Renton Policy Guidelines for Traffic Impact Analysis for New Development, and
conversations with City Renton staff.
Our summary, conclusions and recommendations begin on page seven of this
report.
PROJECT DESCRIPTION
Figure 9 is a vicinity map showing the location of the site and study area.
Figure 2 is a close in area map showing the site location and surrounding street
network.
Figure 3 shows the preliminary site plan.
The primary access street runs from the southwest corner of the site to S 55th St.
through a 50 ft. wide easement on the parcel adjacent to the south side of the site. The
primary access from S. 55"' St. to the site is 28 ft. wide with a sidewalk on the west side
of the street. A secondary gated emergency vehicle access connects to S 551' St.
though a 30 ft. easement. Streets within the site will be 32 ft. wide with a sidewalk on
one side.
The primary site access street is located on the outside of a horizontal curve on
S 55t" St. to optimize sight distance in both east and west directions for vehicles exiting
the site.
Page i
Wilson Park ?raffmy
Development of the Wilson Park plat is expected to occur by the year 2011.
Therefore, for purposes of this study, 2011 is used as the horizon year for this study.
An existing single family home within the project site will be removed with this
development.
TRIP GENERATION AND DISTRIBUTION
The 14 single-family units in the proposed Wilson Park Plat are expected to
generate the vehicular trips during an average weekday and during the street traffic
peak hours as shown below:
Time Period Trip Rate Trips Trips TotalTripsperunitEnteringExiting
67 157
Average Weekday 9.57 134
50% 50%
AM Peak Hour 0.75 8 1125% 75%
PM Peak Hour 1.01 5 14639370
A vehicle trip is defined as a single or one direction vehicle movement with either
the origin or destination (exiting or entering) inside the study site.
The trip generation is calculated using the average trip rates in the Institute of
Transportation Engineers (ITE) Trip Generation, Eighth Edition, for Single Family
Detached Housing (ITE Land Use Code 210). These trip generation values account for
all site trips made by all vehicles for all purposes, including resident, visitor, and service
and delivery vehicle trips.
Figure 4 shows the estimated trip distribution and the calculated site -generated
traffic volumes_ The distribution is based on existing traffic volume patterns, the
characteristics of the road network, the location of likely trip origins and destinations
employment, shopping, social and recreational opportunities), expected travel times,
and previous traffic studies.
Page 2
Tra
EXISTING PHYSICAL CONDITIONS
Street Facilities
Figure 5 shows existing traffic control, number of street lanes and other pertinent
information.
The streets in the study area are classified per the City of Renton
Comprehensive Pian as follows:
Talbot Rd. S Collector Arterial
S 55th St. Local Access
98th Ave S Local access
98th Pi. S Local access
102nd Ave S Local access
S 55th St. consists of two 11 ft. lanes and a shoulder that varies in width from
approximately two to four feet in the vicinity of the project site. A section of S 55th St.
east of the project site consists of several sharp curves and is posted with a 15 mph
advisory speed sign and with chevron arrows at each curve within the section. There is
a left turn pocket on S 55th St. at 98th Ave. S, approximately 125 ft. west of the Wilson
Park site access street.
EXISTING TRAFFIC CONDITIONS
Traffic Volumes
Figure 6 shows existing, future without project and future with project PM peak
hour traffic volumes at the proposed site access street/S 55t' St. intersection. The
proposal generates less than 30 PM peak Dour trips and no other intersection or street
segment in the City of Renton will experience an increase of 5% in traffic volumes due
to this development. Therefore, only the site access street/S 55ffi St. intersection
requires a level of service (LOS) analysis per the Ci of Renton Policy Guidelines for
Traffic Impact Analysis for New Development. A PM peak hour traffic count was
performed on Tuesday, .lune 16, 2509 and is included in the Technical Appendix.
Level of Service Analysis
Level of Service (LOS) is a qualitative measure describing operational conditions
within a traffic flow, and the perception of these conditions by drivers or passengers.
These conditions include factors such as speed, delay, travel time, freedom to
maneuver, traffic interruptions, comfort, convenience, and safety. Levels of service are
given letter designations, from A to F, with LOS A representing the best operating
conditions (free flow, little delay) and LOS F the worst (congestion, long delays).
Page 3
Wilson Park Tra
Generally, LOS A and B are high, LOS C and D are moderate and LOS E and F are
low.
Table 1 shows calculated level of service (LOS) for future conditions including
project traffic at the pertinent street intersection. The LOS was calculated using the
procedures in the Transportation Research Board Highway Capacity Manual 2000. The
LOS shown indicates overall intersection operation. At intersections, LOS is determined
by the calculated average control delay per vehicle. The LOS and corresponding
average control delay in seconds are as follows;
TYPE OF
INTERSECTION A B C D E F
Signalized 9 0. X10.0 and X20.0 and 35.0 and 55.0 and 80.
0 20.0 35.0 55.0 80.0 0
Stop Sign Control 1
0 . 10 and <15 15 and 525 f 25 and <35 35 and X50 50
Accident History
Historical accident data for the section of S. 55"' St. between the intersections
98t" Ave. S and 99t" PI S was obtained from the City of Renton. A total of 4 accidents
occurred from January 1, 2004 through December 31st 2008. Three accidents occurred
on the street section between the intersections, one accident occurred at 99"' PI S and
no accidents occurred at 98tf' Ave. South. Two of the accidents were injury type
accidents with one being a fatality, The fatality was a single vehicle travelling in the
westbound direction approximately 319 ft west of 99"' Pl. South.
None of the accidents occurred at the curve on S. 55"' St. where the site access
street is proposed to be located. Based on the field review and historical accident data
there are no readily apparent safety issues that should result from the proposed
development. The historical accident data is included in the technical appendix.
FUTURE TRAFFIC CONDITIONS (WITHOUT THE PROJECT
Figure 6 shows projected 2011 PM peak hour traffic volumes without the project_
These volumes include the existing traffic volume counts plus background traffic growth.
The background growth factor accounts for traffic volumes generated from other
approved but unbuilt subdivisions and general growth in traffic traveling through the
area.
A 3% per year annual background growth rate was added for each year of the
two year time period from the 2009 traffic count to the 2011 horizon year of the
Page 4
Wilson Park rraffmy
proposal. Cit of Renton historical traffic count data supports the 3% per year growth
rate on S. 55 Street.
FUTURE TRAFFIC CONDITIONS WITH PROJECT
Figure 6 shows the projected future 2011 PM peak hour traffic volumes with the
proposed project. The site -generated PM peak hour traffic volumes shown on Figure 4
were added to the projected future without project volumes to obtain the future with
project volumes.
Table 1 shows calculated LOS for future with project volumes at the Wilson Park
site access street/S. 55th St. intersection. The study intersection operates at an
excellent LOS A for future 2011 conditions including project -generated traffic.
SIGHT DISTANCE EVALUATION
Sight distance on S 55th St. is excellent looking to the west from the proposed
site access street and extends approximately 785 ft. to Talbot Rd. South. Sight
distance to the east is limited by a horizontal curve on S 55u' Street. This curve has a
posted advisory speed of 15 mph. In evaluating sight distance, the generally accepted
rule is to add 5 mph to the posted speed to determine the design speed of the street.
Sight distance requirements looking to the east from the Wilson Park site access street
are therefore based on a 20 mph design speed for the horizontal curve on S 55th Street.
Intersection sight distances and stopping sight distances were measured and
compared to City requirements at the Wilson Park site access street/ S 55th St.
intersection. City of Renton is requirements are based on current AASHTO "Geometric
Design of Highways and Streets" standards.
Intersection Sight Distance
AASHTO standards for a 20 mph design speed require an intersection sight
distance of 145 ft. looking to the left (east) from the site access street (using an eye
height of 3.5 ft. and a vehicle height of 4.25 ft.). Attached in the technical appendix are
Exhibits 9-55 and 9.58 showing the current AASHTO standards for intersection sight
distance. A right tuming vehicle exiting from the side street is required to enter the
westbound lane and accelerate to 85% of the design speed so as not to interfere with
the traffic flow. The field measured intersection sight distance looking to left (east) from
the site access street is 215 ft. thus exceeding the AASHTO required 145 feet.
Intersection sight distance looking to the right from the site access street is excellent
and extends all the way to Talbot Rd. S at approximately 785 ft.
Page 5
Wilson Park lrrafmf
Stopping Sight Distance
Stopping sight distance is the distance traveled while the vehicle driver perceives
a situation requiring a stop, realizes that stopping is necessary, applies the brake, and
comes to a stop. A stopping sight distance of 115 ft. is required for a 20 mph design
speed (using an eye height of 3.5 ft. and an object height of 2 ft.). Attached in the
technical appendix is Exhibit 3-1 showing the current AASHTO standards for stopping
sight distance. There is an approximate 10% downgrade in the westbound direction on
S 55h Street_ The required stopping sight distance is therefore increased an additional
40 ft. to account for a 10% downgrade with a 20 mph design speed. The required
westbound stopping sight distance therefore is 115 + 40 = 155 feet. The field measured
westbound stopping sight distance is 197 ft. thus exceeding the required 155 feet.
Stopping sight distance for eastbound vehicles on S. 55th St. is excellent and extends
from Talbot Rd. S. approximately 785 feet to the site access street.
The City of Renton AASHTO based intersection and stopping sight distance
requirements are met at the Wilson Park site access street/ S 55th St. intersection in
both the east and west directions.
TRAFFIC MITIGATION REQUIREMENTS
The City of Renton requires a Transportation Mitigation Fee payment of $75 per
new daily trip attributed to new development. One existing single family home on site
will be removed. with this development resulting in a net increase of 13 single family
homes. The net new daily trips due to this development are 124 trips (13units x 9.57
daily trips per unit). The estimated Transportation Mitigation Impact Fee is $9,300 (124
daily trips X $75 per daily trip).
Page 6
M1 rk
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
We recommend that the Wilson Park Plat be constructed as shown on the site
plan with the following traffic impact mitigation measures:
Construct the street improvements including curb, gutter and sidewalk for
site access street and intemal site streets as shown on the site pian.
Contribute the approximately $9,300 Transportation Mitigation fee to the
City of Renton.
No other traffic mitigation should be necessary. If you have any
questions, please call 425-522-4118. You may also contact us Via e-mail at
vinoe nwtraffex_eom or IarNCab_nwtrafFex.com.
Very truly yours,
Vincent J. Geglia
Principal
TraffEx
Page 7
C AL. j-1
ate.
3-a
Larry D. Hobbs, P.E.
Principal
TraffEx
TABLE 1
PM PEAK HOUR LEVEL OF SERVICE SUMMARY
WILSON PARK PLAT
TRAFFIC IMPACT ANALYSIS
INTERSECTION EXISTING 2009I VWTHOTUT
PROJECT
Site Access St/S 55h St. I NA I NA I SB (A 9.9)
Number shown is the average control delay in seconds per vehicle for the worst
approach or movement which determines the LOS for an unsignalized
intersection per the Transportation Research Board Highway Capacity Manual
2000
XX) LOS and average control delay for the worst approach or movement at an
unsignalized intersection
SB) southbound approach
Page 8
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Exit 5
Total 14
Wilson Park Plat - City of Renton
PM Peak Hour Trip Generation and Distribution
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Figure
4
Wilson Park Plat - City of Renton Figure
Existing Conditions - 5
Legend
2 Lanes Number of travel lanes
25 mph Speed Limit
Stop Sign Control
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Wilson Park Plat - City of Renton Figure
Existing Conditions - 5
Legend
2 Lanes Number of travel lanes
25 mph Speed Limit
Stop Sign Control
Advisory Speed Sign
Wilson Park Plat - City of Renton Figure
Existing Conditions - 5
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Wilson Park Plat - City of Renton Figure
PM Peak Hour Volumes for Existing and Future Conditions 6
Preps C. Nr' Tex
Traf -c Count Consultants, Inc.
Phone: (425) 861-8866 FAX: (425) 861.8877 F -Mail: TMincigaol.com
WBEfDBE
Intersection: 9Bth Ave S @ S 55th St Date of Count: Tues 6116!09
Location: Renton Checked By: LBP
Tme From North on (SB) From South on (NI3) From Easton (WB) From West on (EB) Interval
Interval 98th Ave S 96th Ave S S 5th St S 5th St Total
Ending at T L S R T L S R T L S R T L I5 R
4:15 P 0 0 0 0 0 1 0 1 0 2 29 0 0 0 66 1 1 122
4:30 P 0 0 0 0 0 0 0 0 1 1 24 0 1 0 771 103
4745 P 0 0 0 0 0 0 0 2 0 1 32 0 0 0 109 0 144
5:00 P 0 0 0 6 0 0 0 1 0 0 34 0 0 0 124 1 160
5:15P 0 0 0 0 0 0 0 0 0 0 17 0 0 0 116 3 138
5:30 P 0 0 0 0 0 2 0 0 0 1 36 0 0 0 112 0 151
5:45 P 0 0 0 0 0 1 0 1 0 1 23 0 0 0 106 1 135
6:00 P 0 0 0 0 0 0 0 0 0 0 29 0 0 0 60 1 110
6:15P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
SM IF 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
6:45P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7:00P Otto 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total
Survey0
0 0 0 0 2
0 01. 0 0 4 D 5 1 6 224 1 0FToTsir,
HV r0a rda
B 1063
0.0%
Peak Hour. 4:30 PM to 5.30 PM
Total0 0 0 0 0 2 0 3 0 2 119 0 0 463 1 4 593
Iproach 0 5 121 467 593
HV r0a rda Ma NO 0.0%
PHF nia 0.63 0.82 0.93 0.93
K •tram:
INT 91
INT 02
INT D3
INT D4
INT 05
INT 06
INT 07
INT 08
INT 09
NT i0
MT 11
INT 12
S 5th St
121 I Peds 0
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0 Bleyciss From: N S E
0 INT 01
0 fNT 02
0 INT 03
0 INT D4
0 INT 05
0 INT 06
INT 07
INT 06 2
0 Special Notes:
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119 121
2 1 587
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Check WB 0.82 n/a
In. 593 NB 0.63 nla
Got: 593 SB n1s nla
Intersection 0.93 0.0%
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TWO WAY STOP CONTROL SUMMARY
jeneral information ite Informati,
Analyst Intersection
Agency/Co. urisdiction Renton
Date Performed 6119/2009 Analysis Year 2011 Future with Project
Analysis Time Period M eak
1ro'ect Description
astlWest Street: S 55th St North/South Street: Site Access St
ct' n Orientation• East-West Stud Period hrs : 0.25terse10
Vehicle Volumes and Adjustments
Major Street Eastbound Westbound
Movement 1 2 3 4 5 B
L T R L T R
Volume 7 494 0 0 128 2
eak-Hour Factor, PHF
iourly Flow Rate, HFR
0.93 1
7
0.93
531
0.93
0
0.93
0
0.93
137
0.93
2
ercent Heavy Vehicles 0 0
Vledian Type Undivided
ZT Channelized 0 0
anes 0 1 0 0 1 0
onfiguration LT TR
J stream Si nal 0 0
Minor Street Northbound Southbound
Movement 7
L
8
T
9
R.
10
L
11
T
12
R
Joiume 0 0 0 1 0 4
eak-Hour Factor, PHF 0.93 0.93 0.93 0.93 0.93 0.93
iourly Flow Rate, HFR 0 0 0 1 1 0 1 4
Dercent Heavy Vehicles 0 0 0 0 0 0
Dercent Grade (%) 0 0
cared Approach N N
Storage 1 0 0
RT Channelized 0 0
anes 0 0 0 0 0 0
onfiguration LR
3ela , Queue Length, and Level of Service
pproach EB WB Northbound Southbound
Movement 1 4 7 8 9 10 11 12
ane Configuration LT LR
vph) 7 5
m) (vph) 1457 738
0.00 0.01
15% queue length 0.01 0.02
ontrol Delay 7.5 0.9
OS A A
4pproach Delay 9.9
4pproach LOS A
rcS2000'1im Copyright C 2000 University ofFlorida, All Rights Reserved Version 4.1
AASHTD--Geometric Dej!A ighways and Streets
Time gap (a) at
design spud of
Desi n vehicle ma r read
Passenger car 6.5
Single -unit truck 8.5
Commination truck 1015
Note: Time gaps are for a stopped vehicle- to turn right
onto or cross a two-lane highway with no median
and grades 3 percent or less. The table values
require adjustment as follows:
For multilane highways:
For crossing a major road with more than two
lanes, anti 0.5 seconds for passenger cars and
0.7 seconds for trucks for each additional lane to
be crossed and for narrow medians that cannot
store the design vehicle.
For minor road approach grades:
If the approach grade is an upgrade that exceeds
3 percent, add 0.1 seconds for each percent
grade.
ExWbit 9-57. Time Gap for Case B2, -Right Turn from
Stop and Case B3 -,-Crossing Maneuver
Note: iratarsection sight distance shown is for a stopped passenger car to tum right onto or crass a
two-lane highway with no median and grades 3 percent or less.' For other conditions, the time
gap must be adjusted and required sight distance recalouiatsd.
ambit 9-58. Design Intersection Sight once ---Case gam --Right Turn from Stop and
Case W-Ccossing Maneuver
M
Metric- lus Custal1l) Y
Intersection sight Intersection sight
Stopp€ng distance for Stopping distance for
Design sight_ passenger cars Design sight Essen er cars
speed distance Calculated Design speed distance Calculated Design
tmlh m rn rn h it ft t
20 20 36.1 40 15 80 143.3 145
30 35 54.2 55 20 115 191.1 195
40 5o 72.3 7S 25 15.5 _ 236,9 240
50 65 90.4 95 30:. .. 204 286.7 290
60 85 1 fi8.4 110 250 334.4 335
70 105 126.5 130
35
40 . 305 362.2- 385
80 130 144.6 145 45 360 430.0 434
S0 160 162.6 165 50 4:25 477.8 480
100 185 180.7 185 55 495 525.5 530
110 220 198.8 200 60 570... 573.3 575
120- 259 216.6 220 65 645 621.1 625
130 285 234.9 2- 5 70 730 668.9 670
75 820' 716.6 720
80.. 910 764.4 765.
Note: iratarsection sight distance shown is for a stopped passenger car to tum right onto or crass a
two-lane highway with no median and grades 3 percent or less.' For other conditions, the time
gap must be adjusted and required sight distance recalouiatsd.
ambit 9-58. Design Intersection Sight once ---Case gam --Right Turn from Stop and
Case W-Ccossing Maneuver
M
Irttersecrfons
Note. Intersection sight distance shown is for a stopped passenger car to tram left onto a
two-lane highway with no median and grades 3 percent or less. For other
conditions, the time gap rntW be adjusted and required sight distance recalculated.
Exhibit 9-55. Design Intersection Sight Dist nce-_4 me BI—Left Tura From Stop
Sight distance design for left turns. at divided -highway intersections ghould consider multiple
design vdhicles and median width. If the design vehicle used to determine sight distance for a
divided -highway intersection is larger than a passenger car, then sight distance for left turns will
need to be checked for that selected design vehicle and for smaller design vehicles as well. If the
divided -highway median is wide enough to stare the design vehicle with a clew%nce to the
through lanes of approximately I m (3 ft] at both ends of the vehicle, no separate analysis for the
departure sight triangle for Ieft turns is needed on the minor -road approach'for the near roadway
to the left. In most cases, the depart= -sight triangle for right turns (Case 132) will provide
sufficient sight distance for a passenger car to cross the .near roadway to reach the median.
Possible exceptions are addressed in the discussion of Case B3.
If the design vehicle can be std in the median with adequate clearance to the through
lanes, a departure sight triangle to the right for. left turns should be provided for that design
vehicle taming left from the median roadway. Where the, ax:dian is not wide enough to store the
design vehicle, a departure sight triangle should be.proyided for that design vehicle to turn left
from the minor -mad approach.
The median width should be considered in determining the number of lanes to be crossed.
The median width should be converted to equivalent lanes. For example, a 7-2-m 124 -ft] median
should be considered as two additional lanes to be crossed in applying the multilane highway
adjustment for time gaps in Exhibit 9-54. Furthermore, a departure sight triangle for left turns
from the mtr dian roadway should be provided for the largest design vehicle that can be stared on
r1
Metric US custalna
fntersectiorn sight Intersedlon sight
Stopping distance for . Stopping distance for
Design sight ssen er cars Design sight p2astNer cars
speed distance Calculated Design speed distance Calculated Design
krnlh to m m Meh) ft ft ft
20 20 41.7 45 15 80 185.4 170
30 35 62.6 65 20 115 2211.5 225
40 50 85,4 8s 25 155 275.6
50 65 104.3 105 30 200 330.6 335
84 85 12511 130 35 250 385.9 390
70 105 146.0 150 40 305 441.0 445
80 130 166.8 170 45 360 496.1 5D0
90 160 187.7 190 50 425 551.3 555
100 185 208.5 210 55 495 606.4 610
110 220 229.4 230 60 570 661.5 665
120 250 250.2 255 65 M 716.6 720
130 28,5 271.1 275 70 730 771.8 775
75 820 826.9 830
80 910 882.0 885
Note. Intersection sight distance shown is for a stopped passenger car to tram left onto a
two-lane highway with no median and grades 3 percent or less. For other
conditions, the time gap rntW be adjusted and required sight distance recalculated.
Exhibit 9-55. Design Intersection Sight Dist nce-_4 me BI—Left Tura From Stop
Sight distance design for left turns. at divided -highway intersections ghould consider multiple
design vdhicles and median width. If the design vehicle used to determine sight distance for a
divided -highway intersection is larger than a passenger car, then sight distance for left turns will
need to be checked for that selected design vehicle and for smaller design vehicles as well. If the
divided -highway median is wide enough to stare the design vehicle with a clew%nce to the
through lanes of approximately I m (3 ft] at both ends of the vehicle, no separate analysis for the
departure sight triangle for Ieft turns is needed on the minor -road approach'for the near roadway
to the left. In most cases, the depart= -sight triangle for right turns (Case 132) will provide
sufficient sight distance for a passenger car to cross the .near roadway to reach the median.
Possible exceptions are addressed in the discussion of Case B3.
If the design vehicle can be std in the median with adequate clearance to the through
lanes, a departure sight triangle to the right for. left turns should be provided for that design
vehicle taming left from the median roadway. Where the, ax:dian is not wide enough to store the
design vehicle, a departure sight triangle should be.proyided for that design vehicle to turn left
from the minor -mad approach.
The median width should be considered in determining the number of lanes to be crossed.
The median width should be converted to equivalent lanes. For example, a 7-2-m 124 -ft] median
should be considered as two additional lanes to be crossed in applying the multilane highway
adjustment for time gaps in Exhibit 9-54. Furthermore, a departure sight triangle for left turns
from the mtr dian roadway should be provided for the largest design vehicle that can be stared on
r1
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112
WILSON PARK DIVISION 2 PLAT
SUPPLEMENTAL TRAFFIC IMPACT ANALYSIS
CITY OF RENTON
Prepared for
Mr. Robert Wilson
21703 60t" St. E.
Lake Tapps, WA 98391
Prepared by
r0qffEX
7-14.4 FFl c EXPERT -s
11410 NE 124" St., #590
Kirkland, Washington 98034
Telephone: 425.522.4118
Fax: 425.522.4311
January 25, 2012
city Of r-'ento-,
DVi5,C11
h,. 2
qp+wV7
Fay Com -
EXHIBIT 12 6
rraff,my
January25, 2012
Mr. Robert Wilson
21703 60th St. E.
Lake Tapps, WA 98391
Re: Wilson Park Division 2 Plat - City of Renton
Supplemental Traffic Impact Analysis
Dear Mr. Wilson:
NCRTHWEST TRAFF/C eXPERTS
11410 NE 124th St. #590 KWr 1, 0 98034Phone. 425.522,4118 Fax: 425,522.4311
We are pleased to present this supplemental traffic impact analysis (TIA) for the
proposed 10 lot Wilson Park Division 2 Plat located on the north side of
S.551h St. in the City of Renton. This TIA supplements the information and analysis
presented in the original Wilson Park Plat TIA, dated June 23, 2009, prepared by
Traffex.
The Wilson Park Division 2 site is adjacent to the southwest corner of the
approved Wilson Park Plat. The proposed project site contains the access road to S.
55 h St. for Wilson Park Plat. The 10 lots of the proposed Wilson Park Division 2 will
have direct driveway connections to the access road connecting the Wilson Park to S.
55th Street. The access road and the location of its intersection to S. 55th St remains the
same as when approved for the original Wilson Park Plat.
The scope of this analysis is based upon the preliminary plat site plan, the Cityof
Renton Policy_ Guidelines for Traffic Impact Analysis for New _Development.
Our summary, conclusions and recommendations begin on page 5 of this report.
PROJECT DESCRIPTION
Figure 1 shows the Wilson Park Division 2 site plan. The site lies between the
southwest corner of the Wilson Park plat and S. 55th Street.
The proposed project utilizes the same access to S. 55th St. as the approved 12
lot Wilson Park plat.
The site access street intersects S. 55th St. on the outside of a horizontal curve
on S. 55th St. to optimize sight distance in both east and west directions for vehicles
entering and exiting the site.
Page 1
Wilson Park Trafff wC
Development of the Wilson Park Division 2 plat is expected to occur by the year
2014. Therefore, for purposes of this study, 2014 is used as the horizon year for this
study.
TRIP GENERATION AND DISTRIBUTION
The 10 single-family units in the proposed Wilson Park Division 2 Plat are
expected to generate the vehicular trips during an average weekday and during the
street traffic peak hours as shown. below:
Time Period Trip Rate Trips Trips Total
Trips per unit Entering Exiting
48
Average Weekday 9.57 96
500 % 50%
AM Peak Hour 0.75
2% 6875%
PM Peak Hour 1.01 41063% 37%
A vehicle trip is defined as a single or one direction vehicle movement with either
the origin or destination (exiting or entering) inside the study site.
The trip generation is calculated using the average trip rates in the Institute of
Transportation Engineers (ITE) Trip Generation Eighth Edition, for Single Family
Detached Housing (ITE Land Use Code 210). These trip generation values account for
all site trips made by all vehicles for all purposes, including resident, visitor, and service
and delivery vehicle trips.
Figure 2 shows the site generated traffic volumes and distribution at the study
intersection. The distribution is based on existing traffic volume patterns, the
characteristics of the road network, the location of likely trip origins and destinations
employment, shopping, social and recreational opportunities), expected travel times,
and previous traffic studies.
EXISTING PHYSICAL CONDITIONS
The streets in the study area are classified per the City of Renton
Comprehensive Plan as follows:
Talbot Rd. S
S55 1h St.
Page 2
Collector Arterial
Local Access
Wilson Park rraffmy
98th Ave S Local access
98th PI. S Local access
102nd Ave S Local access
S 551h St. consists of two 11 ft. lanes and a shoulder that varies in width from
approximately two to four feet in the vicinity of the project site. A section of S 55th St,
east of the project site consists of several sharp curves and is posted with a 15 mph
advisory speed sign and with chevron arrows at each curve within the section. There is
a left tum pocket on S 55th St. at 981h Ave. S, approximately 125 ft. west of the Wilson
Park site access street.
EXISTING TRAFFIC CONDITIONS
Traffic Volumes
Figure 2 shows existing, future without project and future with project PM peak
hour traffic volumes at the proposed site access street/S 55th St. intersection. The
proposal generates less than 30 PM peak hour trips and no other intersection or street
segment in the City of Renton will experience an increase of 5% in traffic volumes due
to this development. Therefore, only the site access street/S 55th St. intersection
requires a level of service (LOS) analysis per the City of Renton Policy Guidelines for
Traffic Impact Analysis for New Development, A PM peak hour traffic count taken for
the Wilson Park Plat TIA was used for this supplemental analysis since traffic growth in
the area has been generally flat over the past several years.
Level of Service Analysis
Level of Service (LOS) is a qualitative measure describing operational conditions
within a traffic flow, and the perception of these conditions by drivers or passengers.
These conditions include factors such as speed, delay, travel time, freedom to
maneuver, traffic interruptions, comfort, convenience, and safety. Levels of service are
given letter designations, from A to F, with LOS A representing the best operating
conditions (free flow, little delay) and LOS F the worst (congestion, long delays).
Generally, LOS A and B are high, LOS C and D are moderate and LOS E and F are
low.
Table 1 shows calculated level of service (LOS) for future conditions including
project traffic at the pertinent street intersection. The LOS was calculated using the
procedures in the Transportation Research Board Highway Capacity Manual 2000. The
LOS shown indicates overall intersection operation. At intersections, LOS is determined
by the calculated average control delay per vehicle at signalized intersections or the
average delay for the worst minor approach at two way stop sign controlled
intersections. The LOS and corresponding average control delay in seconds are as
follows:
Page 3
Wilson Park rraffay
TYPE OF
INTERSECTION A B C D E F
Signalized 10 10.0 and 20.0 and 35.0 and 55.0 and 80.
20.0 35.0 55.0 80.0 0
Stop Sign Control
1
10 and X15 15 and X25 25 and <35 35 and X50 50
FUTURE TRAFFIC CONDITIONS WITHOUT THE PROJECT
Figure 2 shows projected 2014 PM peak hour traffic volumes without the project.
These volumes include the existing traffic volume counts, plus background traffic
growth, plus 12 PM peak hour pipeline project trips generated by the Wilson Park plat.
The background growth factor accounts for traffic volumes generated from other
approved but unbuilt subdivisions and general growth in traffic traveling through the
area.
A 3% per year annual background growth rate was added for each year of the
five year time period from the 2009 traffic count to the 2014 horizon year (for a total of
15%). This will result in a very conservative analysis since traffic volumes in the area
have been generally flat for the past several years and are anticipated to continue this
trend.
FUTURE TRAFFIC CONDITIONS WITH PROJECT
Figure 2 shows the projected future 2014 PM peak hour traffic volumes with the
proposed project. The site -generated PM peak hour traffic volumes were added to the
projected future without project volumes to obtain the future with project volumes.
Table 1 shows calculated LOS for future with project volumes at the Wilson Park
Division 2 site access street/S. 55th St. intersection. The study intersection operates at a
high LOS B for future 2014 conditions, including project -generated traffic, and meets the
City of Renton LOS requirements for intersections.
SIGHT DISTANCE EVALUATION
Sight distance on S 55th St. at the proposed site access street was extensively
evaluated in the Wilson Park TIA and meets the City of Renton intersection and
stopping sight distance requirements in both the east and west directions.
Page 4
Wilson Park Traffmy
TRAFFIC MITIGATION REQUIREMENTS
The City of Renton requires a Transportation Mitigation Fee payment of $75 per
new daily trip attributed to new development. The net new daily trips due to this
development are 96 trips (10units x 9.57 daily trips per unit). The estimated
Transportation Mitigation Impact Fee is $7,200 (96 daily trips X $75 per daily trip).
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
We recommend that the Wilson Park Division 2 Plat be constructed as shown on
the site plan with the following traffic impact mitigation measures:
Construct the street improvements including curb, gutter and sidewalk for
site access street as shown on the site plan.
Contribute the approximately $7,200 Transportation Mitigation fee to the
City of Renton.
No other traffic mitigation should be necessary. If you have any
questions, please call 425-5224118. You may also contact us via e-mail at
vince(L-tnwtraffex.com or larry@nwtraffex.com.
Very truly yours,
Vincent J. Geglia
Principal
TraffEx
Page 5
as: "02
Larry D. Hobbs, P.E.
Principal
TraffEx
TABLE 1
PM PEAK HOUR LEVEL OF SERVICE SUMMARY
WILSON PARK PLAT
TRAFFIC IMPACT ANALYSIS
INTERSECTION EXISTING 2014WITHOUTI
PROJECT
2011 WITHIPROJECT
Site Access SVS 55th St.
I -
NA- B 10.4 SB B 10.5 SB
XX Number shown is the average control delay in seconds per vehicle for the
minor approach for unsignalized intersections, which determines the LOS for
intersections per the Transportation Research Board Highway Capacity Manual
2000
B Indicates calculated level of service
SB (Southbound) Indicates direction of the minor approach for unsignalized
intersections
Page 6
w LE 5,905+/-S0. ff,
5,5604/ -Sy FT,
s '
IN LOT 2 tG`.
I 5,905+f -S}. R.
LOT
LITT
1 » 5,77ZE.sI243i 5 5
MOA, LOT 10
n 6,779+f-50.
SSiH AVE. SOUTH
ror.w
Wilson Park Division 2 Plat - City of Renton
Site Plan
Figure
1
i
1 rlM ES AN-.wv .71707'_ _--"- I -
1 L -PO '
l a-zz x RACY A
y 5,9094/-99,i1.
i
7
fol.ft'
rY
LOT 6
5585+/ -SA FS. \
1 4
taxsr bio i
w LE 5,905+/-S0. ff,
5,5604/ -Sy FT,
s '
IN LOT 2 tG`.
I 5,905+f -S}. R.
LOT
LITT
1 » 5,77ZE.s I243i 5 5
MOA, LOT 10
n 6,779+f-50.
SSiH AVE. SOUTH
ror.w
Wilson Park Division 2 Plat - City of Renton
Site Plan
Figure
1
NL7R7-H1YE5'T
TRA rric Ex,-,rp ns
i
SE MTO ST
F SEMN ST
ss a
r
MM it i NTH ST
M
j sO.Ow sr
t
Future Project Future
Without Generated With
Existing Project Trips Project
0-,J k 0
468-121
6
JJ -
2
140
5
J `
1
0'0`0
11-1 ` 3
544-0-340540
Wilson Park Division 2 Plat - City of Renton Figure
PM Peak Hour Volumes for Existing and Future Conditions 2
TECHNICAL APPENDIX
TWO-WAY STOP CONTROL SUMMARY
General Information Site Information
nal s1
enc /Co.
Date Performed 6/19/2009
Analysis Time Period IPMpeak
East/West Street: S 55th St
7
5
intersection Orientation: East-West
Volume
Vehicle Volumes and Adjustments
Major Street
0.93
Eastbound
Movement 1 2
Percent Grade (%)
L T
olume 6 540
eak-Hour Factor, PHF 0.93 0.93
Hourly Flow Rate, HFR 6 580
Percent HeavyVehicles 0
Median Type
RT Channelized
Lanes 0 1
onfi uration LT
stream Signal 0
Minor Street Northbound
Movement 7
5
L
Volume 0
Peak -Hour Factor, PHF 0.93
Hourly Flow Rate, HFR 0
Percent Heavy Vehicles 0
Percent Grade (%)
RT Channelized
Lanes
Configuration
Dela. Queue L
ration
km) tvpn)
c
5% queue leng
Control Delay
LOS
Approach Delay
Approach LOS
1--
and Level of
EB
1
LT
6
1441
0.00
0.01
7.5
A
WB
4
Intersection
5
Jurisdiction
T
Renton
Analysis Year
2
2014 Future Without
Project
0.93
150 2
North/_South Street: Site Access St
5tudv Period (hrs): 0.25
Illllllllii
Northbound
7 8 9
Istbound
5 6
T R
140 2
0.93 0.93
150
Northbound
7 8 9
Istbound
5 6
T R
140 2
0.93 0.93
150 2
0
a
HCS2000 Copyright C, 2000 University of Florida, All Rights Reserved Version 4.1 c
r
0
Southbound
0
0
0
0
II
II
HCS2000 Copyright C, 2000 University of Florida, All Rights Reserved Version 4.1 c
TWO-WAY STOP CONTROL SUMMARY
General Information Site Information
Co. Performed
Analysis Time Period
Project Description
6/1912009
PM peak
Intersection
urisdiction
Analysis Year
Renton
2014 Future with Project
East/West Street: S 55th St North/South Street: Site Access St
Intersection Orientation: Fast -West IStudy Period hrs : 0.25
Vehicle Volumes and Adjustments
Major Street Eastbound Westbound
Movement 1 2 3 4 5 6
L T R L T R
Volume 11 540 0 0 140 3
Peak -Hour Factor, PHF 0.93 0.93 0.93 0.93 0.930.93
Hour! Flow Rate, HFR 11 580 0 0 150 3
Percent Heavy Vehicles 0 0
Median Type Undivided
RT Channelized 0 0
Lanes 0 1 0 0 0
Configuration LT TR
Upstream Signal 0 0
Minor Street Northbound Southbound
Movement 7 8 9 10 11 12
L T R L T R
Volume 0 0 0 2 0 6
Peak -Hour Factor, PHF 0.93 0.93 0.93 0.93 0.93 0.93
Hourly Flow Rate, HFR 00 0 1 0 2 i 0 6
Percent Heavy Vehicles 0 0 0 0 0 0
Percent Grade (°1°) 0 0
Flared Approach N N
Storage 0 0
RT Channelized 0 0
Lanes 0 0 0 0 0 0
nfiguration LR
Queue Len th, and Level of ServiceDpenay,
proach EB WB Northbound Southbound
vement 1 4 7 8 9 10 11 12
Lane Configuration LT LR
vph) 11 8
C (m) (vph) 1440 668
Ic 0.01 0.01
5% queue length 0.02 Q.04
ontrol Delay 7.5 10,5
LOS A g 4
Approach Delay 10.5
pproach LOS g
HCS2000TM Copyright C 2000 University of Florida, All Rights Reserved Version 4.l c