HomeMy WebLinkAbout2020-04-30 Traffic Impact StudyS:\projects\ARCHIVE\17-27 Tanner Creek\docs\Tanner Creek Subdivision - TIS 030718.docx
181 East 50th St
Garden City, ID 83714
(208) 484-4410
November 8, 2017
Revised March, 7, 2018
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
Prepared For:
Challenger Development
1977 Overland Road
Meridian, ID 83642
3/7/18 3/7/18
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
November 2017 i
Table of Contents
EXECUTIVE SUMMARY ........................................................................................................................ 1
Introduction .............................................................................................................................................. 1
Proposed Development ............................................................................................................................. 1
Proposed Mitigation for 2017 Existing Traffic ........................................................................................ 1
Proposed Mitigation for 2022 (Build-Out Year) Background Traffic ...................................................... 2
Proposed Mitigation for 2022 (Build-Out Year) Total Traffic ................................................................. 2
PROPOSED DEVELOPMENT................................................................................................................. 3
Location .................................................................................................................................................... 3
Current Development ............................................................................................................................... 3
Previous Development .............................................................................................................................. 4
STUDY APPROACH ................................................................................................................................. 5
Study Area ................................................................................................................................................ 5
Study Period ............................................................................................................................................. 5
EXISTING CONDITIONS ........................................................................................................................ 5
Road System ............................................................................................................................................. 5
Existing Traffic Volumes ......................................................................................................................... 6
Intersection Crash Data ............................................................................................................................ 8
Roadway Network Improvements ............................................................................................................ 8
PROJECTED TRAFFIC ............................................................................................................................ 8
Background Traffic .................................................................................................................................. 8
Site Traffic .............................................................................................................................................. 10
Trip Generation .................................................................................................................................. 10
Trip Capture ....................................................................................................................................... 10
Pass-by Trips ...................................................................................................................................... 10
Modal Split ......................................................................................................................................... 11
Trip Distribution and Assignment ...................................................................................................... 11
Total Traffic............................................................................................................................................ 11
TRAFFIC ANALYSIS .............................................................................................................................. 14
2017 Existing Traffic .............................................................................................................................. 14
Roadway Segment Level of Service .................................................................................................. 14
Intersection Capacity Analysis and Level of Service ......................................................................... 15
Mitigation ........................................................................................................................................... 15
2022 Build-Out Year Background Traffic .............................................................................................. 16
Roadway Segment Level of Service .................................................................................................. 16
Intersection Capacity Analysis and Level of Service ......................................................................... 16
Mitigation ........................................................................................................................................... 17
2022 Build-Out Year Total Traffic ......................................................................................................... 18
Roadway Segment Level of Service .................................................................................................. 18
Intersection Capacity Analysis and Level of Service ......................................................................... 18
Mitigation ........................................................................................................................................... 19
Cut Through Traffic ........................................................................................................................... 19
Site Access and Circulation .................................................................................................................... 20
APPENDIX ................................................................................................................................................. A
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
November 2017 ii
List of Figures
Figure 1 – Site Location and Vicinity ........................................................................................................... 3
Figure 2 – Preliminary Site Plan ................................................................................................................... 4
Figure 3 – 2017 Existing AM and PM Peak Hour Traffic ............................................................................ 7
Figure 4 – 2022 Build-Out Year Peak Hour Redistributed Background Traffic .......................................... 9
Figure 5 – Site Traffic Distribution Patterns ............................................................................................... 11
Figure 6 – Build-Out AM and PM Peak Hour Site Traffic ......................................................................... 12
Figure 7 – 2022 Build-out Year AM and PM Peak Hour Total Traffic ...................................................... 13
Figure 8 – Proposed Access Locations and Internal Roadway ADTs ........................................................ 20
List of Tables
Table 1 – 2017 Existing ADT and Directional Peak Hour Volumes Summary ........................................... 6
Table 2 – Build-Out Site Trip Generation Summary .................................................................................. 10
Table 3 – Roadway Segment Thresholds – 2017 Existing Traffic on Local Streets .................................. 14
Table 4 - Roadway Segment Level of Service - 2017 Existing Traffic on Collector Roads ...................... 14
Table 5 – Intersection Level of Service – 2017 Existing Traffic Stop Controlled ...................................... 15
Table 6 – Intersection Level of Service - 2017 Existing Traffic Signal Controlled ................................... 15
Table 7 – Lane Group v/c Ratio – 2017 Existing Traffic Intersection Signal Controlled .......................... 15
Table 8 – Roadway Segment Thresholds – 2022 Background Traffic on Local Streets ............................ 16
Table 9 - Roadway Segment Level of Service – 2022 Background Traffic on Collector Roads ............... 16
Table 10 – Intersection Level of Service – 2022 Background Traffic Stop Controlled ............................. 16
Table 11 – Intersection Level of Service - 2022 Background Traffic Signal Controlled ........................... 17
Table 12 – Lane Group v/c Ratio – 2022 Background Traffic Intersection Signal Controlled .................. 17
Table 13 – Roadway Segment Thresholds – 2022 Total Traffic on Local Streets ..................................... 18
Table 14 - Roadway Segment Level of Service – 2022 Total Traffic on Collector Roads ......................... 18
Table 15 – Intersection Level of Service – 2022 Total Traffic Stop Controlled ........................................ 18
Table 16 – Intersection Level of Service - 2022 Total Traffic Signal Controlled ...................................... 19
Table 17 – Lane Group v/c Ratio – 2022 Total Traffic Intersection Signal Controlled ............................. 19
Table 18 – Site Access Intersection Level of Service – 2022 Build-Out Year Total Traffic ..................... 21
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
1
EXECUTIVE SUMMARY
Introduction
Thompson Engineers, Inc. has been retained to prepare a traffic impact study (TIS) for the proposed
Tanner Creek Subdivision located on Waltman Road in Meridian, Idaho, as shown in Figure 1. The TIS
evaluates the potential traffic impacts resulting from the development and make recommendations for
mitigation of the impacts. The scope of this report was determined through coordination with the Ada
County Highway District (ACHD) and was prepared in accordance with ACHD Policy, Section 7106 –
Traffic Impact Studies.
Proposed Development
1. Tanner Creek Subdivision is a proposed residential development containing 85 single-family
detached housing units, 44 townhouses, and 280 apartments with an expected 2022 build-out year.
2. Based on ITE Trip Generation Manual, the development is estimated to generate approximately 2,928
trips per day, 226 trips during the AM peak hour and 282 trips during the PM peak hour.
The development is not expected to retain internal trips within the site or generate pass-by trips.
All trips generated by the development are expected to be made by personal vehicles.
The estimated site traffic distribution patterns are:
10% west of the site
90% east of the site
3. All proposed internal roadways are projected to carry less than 1,000 vehicles per day.
4. The proposed driveway locations on Waltman Lane generally meet the ACHD’s access spacing and
design.
5. This project will connect the existing subdivisions to the west to Waltman Lane. This will provide
shorter travel route to many destinations for many trips originating within the existing subdivisions.
As a result, we anticipate that traffic from the existing subdivisions will redistribute and use Waltman
Lane instead of Linder Road to access the transportation system
6. The existing subdivisions to the west are currently served only by Linder Road to access the
transportation system. There are more than 700 homes in the traffic shed. The connection to
Waltman Lane will provide a critical link to the transportation system and will greatly increase the
safety of the existing subdivisions.
Proposed Mitigation for 2017 Existing Traffic
7. All of the intersections in the study area operate at an acceptable level of service under existing traffic
conditions. No mitigation is necessary.
8. All of the roadway segments studied operate below the recommended maximum threshold for local or
collector roads. Not mitigation is necessary.
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Proposed Mitigation for 2022 (Build-Out Year) Background Traffic
9. For background traffic conditions, it was assumed that the connection from the existing subdivisions
to the west to Waltman Lane was complete and traffic will redistribute. With traffic growth and
redistributed traffic, all of the intersections are anticipated to operate at an acceptable level of service.
No mitigation is necessary.
10. All of the roadway segments studied are anticipated to operate below the recommended maximum
threshold for local or collector roads. No mitigation is necessary.
Proposed Mitigation for 2022 (Build-Out Year) Total Traffic
11. With the addition of site traffic added to background traffic, all of the intersections are anticipated to
operate at an acceptable level of service. No mitigation is necessary.
12. All of the roadway segments studied are anticipated to operate below the recommended maximum
threshold for local or collector roads. No mitigation is necessary.
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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PROPOSED DEVELOPMENT
Location
The proposed Tanner Creek Subdivision is located on Waltman Lane in Meridian, Idaho. Figure 1 shows
the site location and its vicinity.
Current Development
Figure 2 shows the preliminary site plan with proposed access locations and land uses. Tanner Creek
Subdivision is a proposed residential subdivision containing 85 single-family lots, 44 townhouses, and
280 apartments. The expected build-out year is 2022. The development is proposing two full access
approaches on Waltman Lane for site access. The development will also connect to the subdivision to the
west via Ruddy Drive.
Figure 1 – Site Location and Vicinity
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Figure 2 – Preliminary Site Plan
Previous Development
A previous application for this site was for 200,000 SF of retail space and 150,000 SF of office park. The
site was estimated to generate 10,300 trips per day and 975 during the PM peak hour, according to the
ACHD staff report for Browning Plaza, dated March 5, 2008.
Waltman Lane
Ruddy Drive
85 Single
Family
Dwellings
44
Townhouses
280 Apartments
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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STUDY APPROACH
This study follows the ACHD’s requirements for transportation impact studies. The study area, specific
parameters and requirements for the study were coordinated with ACHD’s staff. Scoping emails and
results from the Community Planning Association of Southwest Idaho (COMPASS) area of influence
model runs are included in the appendix.
Study Area
The following study area intersections were identified by ACHD for the traffic impact analysis:
Meridian Road/Main Street and Central Drive/Waltman Lane
Linder Road and Gander Drive
Proposed access driveway intersections on Waltman Lane
The following study area roadway segments were identified by ACHD for the traffic impact analysis:
Waltman Lane east of the site
Elder Drive east of Pelican Way
Gander Drive east of Linder Road
Pelican Way south of Waltman Drive
Waltman Drive east of Pelican
Study Period
The analysis peak periods will be the AM and PM peak hours of operation of the transportation system.
The analysis years are:
2017 existing traffic
2022 build-out year background traffic
2022 build-out year total traffic
EXISTING CONDITIONS
Road System
A brief description of the existing roadways and intersections within the study area is described below.
The roadway functional classification is based on COMPASS 2040 Functional Classification Map, which
does not include collector or local streets.
Waltman Lane is not classified in the COMPASS map. Waltman Lane functions as a collector street
with a posted speed limit of 25 miles per hour (mph). In front of the site, it has one travel lane in each
direction with a rural section without curb, gutter, sidewalk or designated bike lane. Waltman Lane ends
just to the west of the site.
Linder Road is classified as a principal arterial road in the COMPASS map with a posted speed limit of
35 mph. It has one lane in each direction with a rural section with curb, gutter, and sidewalk in the
vicinity of this project. Linder Road terminates at I-84 on the south end.
Elder Drive, Gander Drive, Pelican Way, Pintail Drive, and Waltman Drive are not classified by
COMPASS. They function as local roads with front on housing access. These streets do not have posted
speed limits, but the City if Meridian City Code designates a speed limit of 20 mph on local roads. All of
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
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the roads are urban sections approximately 36 feet wide, with curb, gutter and sidewalk. All of the roads
permit on street parking.
Waltman/Central and Main/Meridian intersection is a signal controlled intersection. Waltman Lane
has two left turn lanes, one through lane, and one right turn lane at the intersection. This intersection is
the terminus of the Main Street and Meridian Road one way couplet. All approaches have multiple lanes.
Gander Drive and Linder Road intersection is a stop-controlled intersection with stop sign on the
Gander Drive. The intersection has one shared lane for all movements on all approaches.
Existing Traffic Volumes
AM and PM peak hour traffic counts were obtained at the study intersections on October 16, 2017. The
peak our intersection turning movement counts were collected on a weekday for a 2-hour period at 15-
minute intervals between 7:00 and 9:00 during the AM peak travel period hour and between 4:00 and
6:00 during the PM peak travel period, which are included in the appendix. Existing peak hour traffic
volumes are summarized in Figure 3.
24-hour counts were also obtained for the study area roadway segments – summarized in Table 1.
Table 1 – 2017 Existing ADT and Directional Peak Hour Volumes Summary
Roadway Segment ADT Peak Hour Directional
Eider Drive east of Pelican Way 248
AM WB 19
PM EB 17
Gander Drive east of Linder Road 694
AM WB 41
PM EB 42
Pelican Way south of Waltman Drive 679
AM NB 46
PM SB 39
Pintail Drive east of Spoonbill Avenue 1444
AM WB 87
PM EB 98
Waltman Drive east of Pelican Way 182
AM WB 12
PM EB 16
Waltman Lane east of Johnson 190
AM WB 7
PM WB 17
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Figure 3 – 2017 Existing AM and PM Peak Hour Traffic
AM Peak Hour
PM Peak Hour
1 1067 86 58 13
1 88 27
1 1 0
3 128 6
4 1552 320 97 1
21
21
7 1581 154 144 41
8 204 21
0 0
9 468 6
6 1612 253 110 0
21
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Intersection Crash Data
The most current five-year crash data (2011-2015) was obtained from the Local Highway Technical
Assistance Council (LHTAC) website (http://gis.lhtac.org/safety/). No accidents were reported on
Waltman Lane. Only two accidents were reported in the subdivision to the west along the anticipated
travel routes.
Roadway Network Improvements
At the time of this study, the ACHD 2016 Capital Improvement Plan (CIP) included a project to widen
Linder Road from 2 lanes to 5 lanes. The ITD Idaho Transportation Investment Program (ITIP) FY2017-
2021, FY2018-2024 (Draft) included a plan to construct an overpass of Linder Road over Interstate 84.
These projects are in the 2031-2035 planning period and are unfunded.
This project will connect the subdivision to the west to Waltman Lane. This will provide a shorter route
to destinations such as shopping centers and jobs, as well as shorter access to the interstate. It is
anticipated that this improvement will impact existing travel patterns.
PROJECTED TRAFFIC
Background Traffic
The areas adjacent to the site are mostly build-out. The following annual growth rates were used to
estimate the traffic growth for the study area roadways and intersections:
1.5% on Meridian Road, and Main Street
1.0% on Waltman Lane and Central Drive
0.0% on the local roads west of the site.
0.5% on Linder Road
As noted above, the connection of Ruddy Drive to Waltman Lane will change the travel patterns of
people in the subdivision to the west. The redistributed traffic is assigned to the transportation system in
the background phase of this study.
Figure 4 shows the 2022 build-out year redistributed background turning movement traffic for the AM
and PM peak hours.
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Figure 4 – 2022 Build-Out Year Peak Hour Redistributed Background Traffic
AM Peak Hour
PM Peak Hour
11 1149 93 59 7
33 92 10
12 6
67 135 6
25 1672 345 59 7
21
21
44 1703 166 148 23
29 214 10
7 12
51 492 6
78 1737 273 113 0
21
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Site Traffic
Trip Generation
Site trip generation is usually estimated using the procedures recommended in the latest edition of the
Trip Generation Manual (9th edition), published by the Institute of Transportation Engineers, in the
absence of site-specific data. The site trip generation is obtained by applying the average trip generation
rates obtained from the Manual for the proposed land use within the development. Table 2 summarizes
the site trip generation. At full build-out, the development is estimated to generate approximately 2,928
trips per day, 226 trips during the AM peak hour and 282 trips during the PM peak hour.
Table 2 – Build-Out Site Trip Generation Summary
The previous application for a retail and office development generated 10,300 trips per day, 975 of which
occurred in the PM peak hour. The ACHD staff report did not provide AM peak hour trip generation.
The proposed development will generate less than 30% of the volume of traffic than the former
development proposal.
Trip Capture
Based on the proposed land use, the development is not expected to retain trips within the site at full
build-out. No trip reduction for internal capture trip was assumed in the traffic impact analysis.
Pass-by Trips
The development is residential and is not expected to attract pass-by trips. No pass-by trips were assumed
in the traffic impact analysis.
Total
Single-Family Detached
Housing 210 85 DU 9.52 810 ----810 50%405 50%405
Residential/
Condominium Townhouse 230 44 DU 5.81 256 ----256 50%128 50%128
Apartment 220 280 DU 6.65 1,862 ----1,862 50%931 50%931
2,928 2,928 1,464 1,464
Single-Family Detached
Housing 210 85 DU 0.75 64 ----64 25%16 75%48
Residential/
Condominium Townhouse 230 44 DU 0.44 19 ----19 17%3 83%16
Apartment 220 280 DU 0.51 143 ----143 20%29 80%114
226 226 48 178
Single-Family Detached
Housing 210 85 DU 1.00 85 ----85 63%54 37%31
Residential/
Condominium Townhouse 230 44 DU 0.52 23 ----23 67%15 33%8
Apartment 220 280 DU 0.62 174 ----174 65%113 35%61
282 282 182 100
Total Trips
Weekday AM Peak Hour (vph)
Total Trips
Weekday PM Peak Hour (vph)
Total Trips
Weekday Daily (vpd)
Land Use
ITE
Code Size Unit
Trip Rate
per Unit
Total
Trips
Internal
Capture
Trips
Pass-by
Trips
PrimaryTrip
Entering Exiting
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
11
Modal Split
The development is not expected to generate trips made by other modes beside personal and commercial
vehicles. All trips generated by the development were assumed to be made by personal and commercial
vehicles.
Trip Distribution and Assignment
In order to determine the impacts, trips generated by the development must be distributed and assigned to
the transportation system. Site traffic was distributed and assigned to the external roadway system based
on the current travel patterns, site layout and the general location of the site within the area. Figure 5
shows the expected site traffic distribution patterns. Figure 6 summarizes the estimated build-out site
traffic.
Figure 5 – Site Traffic Distribution Patterns
Total Traffic
The site traffic is then added to the background traffic as determined above. Figure 7 shows the total
traffic at each intersection for AM and PM peak hour traffic conditions for the 2022 build-out year.
10%
90%
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Figure 6 – Build-Out AM and PM Peak Hour Site Traffic
AM Peak Hour
PM Peak Hour
13 0 0 0 5
48 0 8
16 4 0 0 60 10
96 0 0 0 10 0 33
26 0 0 0 0 0 60 0 100
21
21
3 4
3 4
49 0 0 0 18
27 0 10
9 16 0 60 60
54 0 0 10 0 117
98 0 0 0 0 0 60 0 100
21 3 4
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Figure 7 – 2022 Build-out Year AM and PM Peak Hour Total Traffic
AM Peak Hour
PM Peak Hour
24 1149 93 0 59 12
81 92 0 18
28 10 0 0 0 167 46
163 135 0 6 0 46 0 33
0
51 1672 345 0 99 1 0 167 0 100
21
21
3 4
3 4
93 1703 166 0 148 41
56 214 0 20
16 28 0 0 0 0 100 180
105 492 0 6 0 180 0 117
176 1737 273 0 113 0 0 100 0 60
21 3 4
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
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TRAFFIC ANALYSIS
Roadway segment was evaluated based on ACHD level of service standards in accordance with Table 2
of the ACHD Policy Manual, Section 7106. The roadway segment level of service is based on the
maximum peak hour directional volume for different roadway functional classifications, number of
through lanes, and left-turn type. The minimum acceptable level of service is LOS D for collectors.
Local streets should be limited to a maximum of 2,000 vehicles per day, based on section 7207.3.1 of the
ACHD Policy Manual.
Intersection capacity analysis was performed using the Synchro 10 (Version 10.1.26), which utilizes the
2010 Highway Capacity Manual methodologies. All parameters used in the analysis were based on
existing data when available or Synchro default values, when not available. Level of service for
intersection is based on the average delay of vehicles traveling through the intersection. According to
ACHD policy, the minimum acceptable level of service is LOS D with a v/c ratio of 0.90 for the
intersection and 1.00 for a lane group.
2017 Existing Traffic
Roadway Segment Level of Service
The study area roadway segments level of service were evaluated with 2017 existing traffic. Table 3
summarizes the review for local roads impacted. Table 4 summarizes the review for collector roads
impacted. All study area roadway segments currently meets minimum operational thresholds with the
existing lane configuration. No roadway capacities improvements are needed to mitigate 2017 existing
traffic.
Table 3 – Roadway Segment Thresholds – 2017 Existing Traffic on Local Streets
Roadway Segment ADT
Below
Threshold?
Eider Drive east of Pelican Way 248 Yes
Gander Drive east of Linder Road 694 Yes
Pelican Way south of Waltman Drive 679 Yes
Pintail Drive east of Spoonbill Avenue 1444 Yes
Waltman Drive east of Pelican Way 182 Yes
Table 4 - Roadway Segment Level of Service - 2017 Existing Traffic on Collector Roads
Roadway Segment
Functional
Class.
Left-Turn
Lane Type
LOS D
Volume
Threshold
(vph)
Peak Hour
Directional
Volume (vph) Meet
Minimum
Acceptable
LOS?
AM
Peak
PM
Peak
Waltman Lane East of Johnson Collector None 425 7 17 Yes
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Intersection Capacity Analysis and Level of Service
To determine the existing traffic impacts, the study area intersections were analyzed with the existing
intersection control and lane configuration and 2017 peak hour traffic. Copies of the calculations are
included in the appendix. Table 5, Table 6 and Table 7 summarize the measures of effectives (MOE)
from the intersection capacity analysis. Based on traffic analysis results, both study area intersections are
currently operating at an acceptable level of service.
Table 5 – Intersection Level of Service – 2017 Existing Traffic Stop Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Linder Road
And
Gander Drive
Stop
(WB Gander)
LOS
(WB) A A
Delay (s/v)
(WB) 9.1 9.4
Worst Lane
Group LOS A (WB) A (WB)
Table 6 – Intersection Level of Service - 2017 Existing Traffic Signal Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Meridian/Main
and
Waltman/Central
Traffic Signal
Intersection
LOS A C
Intersection
Delay (s/v) 8.6 25.0
Intersection
v/c 0.52 0.70
Worst Lane
Group LOS E (EBTR) E (WBR)
Table 7 – Lane Group v/c Ratio – 2017 Existing Traffic Intersection Signal Controlled
Intersection Approach
AM Peak Hour PM Peak Hour
LT THRU RT LT THRU RT
Meridian/Main
and
Waltman/Central
NB 0.44 0.49 0.31 0.46 0.61 0.30
SB 0.80 0.31 0.00 0.86 0.51 0.01
EB 0.03 0.06 0.21 0.10 0.00 0.23
WB 0.52 0.0 0.78 0.90 0.00 0.86
Mitigation
No mitigation is necessary to address issues with 2017 existing traffic.
3
2
1
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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2022 Build-Out Year Background Traffic
Roadway Segment Level of Service
The study area roadway segments level of service were evaluated with 2022 background traffic. Table 8
summarizes the results for the local roads. Table 9 summarizes the results for the collector road. All study
area roadway segments are expected to meet minimum operational thresholds with the existing lane
configuration. No roadway capacities improvements are needed to mitigate 2022 background traffic.
Table 8 – Roadway Segment Thresholds – 2022 Background Traffic on Local Streets
Roadway Segment
Existing
ADT
Redistributed
Traffic
Total
Traffic
Below
Threshold?
Eider Drive east of Pelican Way 248 +480 728 Yes
Gander Drive east of Linder Road 694 -285 409 Yes
Pelican Way south of Waltman Drive 679 +285 964 Yes
Pintail Drive east of Spoonbill Avenue 1444 -850 594 Yes
Waltman Drive east of Pelican Way 182 +100 282 Yes
Table 9 - Roadway Segment Level of Service – 2022 Background Traffic on Collector Roads
Roadway Segment
Functional
Class.
Left-Turn
Lane Type
LOS D
Volume
Threshold
(vph)
Peak Hour
Directional
Volume (vph) Meet
Minimum
Acceptable
LOS?
AM
Peak
PM
Peak
Waltman Lane East of Johnson Collector None 425 107 134 Yes
Intersection Capacity Analysis and Level of Service
To determine the 2022 background traffic impacts, the study area intersections were analyzed with the
existing intersection control and lane configuration. Copies of the calculations are included in the
appendix. Table10, Table 11 and Table 12 summarize the intersection capacity analysis results. All
study area intersections are projected to meet minimum operational thresholds.
Table 10 – Intersection Level of Service – 2022 Background Traffic Stop Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Linder Road
And
Gander Drive
Stop
(WB Gander)
LOS
(WB) A A
Delay (s/v)
(WB) 9.2 9.6
Worst Lane
Group LOS A (WB) A (WB)
1
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Tanner Creek Subdivision
Meridian, Idaho
March 2018
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Table 11 – Intersection Level of Service - 2022 Background Traffic Signal Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Meridian/Main
and
Waltman/Central
Traffic Signal
Intersection
LOS C D
Intersection
Delay (s/v) 20.7 36.0
Intersection
v/c 0.56 0.74
Worst Lane
Group LOS E (SBL) F (SBL)
Table 12 – Lane Group v/c Ratio – 2022 Background Traffic Intersection Signal Controlled
Intersection Approach
AM Peak Hour PM Peak Hour
LT THRU RT LT THRU RT
Meridian/Main
and
Waltman/Central
NB 0.68 0.56 0.36 0.81 0.68 0.33
SB 0.81 0.36 0.01 0.87 0.61 0.05
EB 0.18 0.12 0.76 0.20 0.08 0.71
WB 0.54 0.05 0.80 0.91 0.04 0.87
Mitigation
The westbound movement on Central Drive will operate at LOS F in the PM peak hour. This movement
already has two lanes. The north and south bound through movements have three lanes. There is not
much that can be done to mitigate this intersection. The overall intersection operation is acceptable. The
LOS of the turn movements could be improved by adjusting the timing, but the overall delay at the
intersection would increase.
3
2
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Meridian, Idaho
March 2018
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2022 Build-Out Year Total Traffic
Roadway Segment Level of Service
The study area roadway segments level of service were evaluated with 2022 total traffic. Table 13 and
Table 14 summarize the results. All study area roadway segments are expected to meet minimum
operational thresholds with the existing lane configuration. No roadway capacities improvements are
needed to mitigate 2022 total traffic.
Table 13 – Roadway Segment Thresholds – 2022 Total Traffic on Local Streets
Roadway Segment
Background
Traffic
Site
Traffic
Total
Traffic
Below
Threshold?
Eider Drive east of Pelican Way 728 250 978 Yes
Gander Drive east of Linder Road 409 250 659 Yes
Pelican Way south of Waltman Drive 964 250 1114 Yes
Pintail Drive east of Spoonbill Avenue 594 50 644 Yes
Waltman Drive east of Pelican Way 282 50 332 Yes
Table 14 - Roadway Segment Level of Service – 2022 Total Traffic on Collector Roads
Roadway Segment
Functional
Class.
Left-Turn
Lane Type
LOS D
Volume
Threshold
(vph)
Peak Hour
Directional
Volume (vph) Meet
Minimum
Acceptable
LOS?
AM
Peak
PM
Peak
Waltman Lane East of Johnson Collector None 425 267 297 Yes
Intersection Capacity Analysis and Level of Service
To determine the 2022 total traffic impacts, the study area intersections were analyzed with the existing
intersection control and lane configuration. Copies of the calculations are included in the appendix.
Table15, Table 16 and Table 17 summarize the intersection capacity analysis results. All study area
intersections are projected to meet minimum operational thresholds.
Table 15 – Intersection Level of Service – 2022 Total Traffic Stop Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Linder Road
And
Gander Drive
Stop
(WB Gander)
LOS
(WB) A A
Delay (s/v)
(WB) 9.2 9.7
Worst Lane
Group LOS A (WB) A (WB)
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Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
19
Table 16 – Intersection Level of Service - 2022 Total Traffic Signal Controlled
Intersection Control MOEs
AM
Peak Hour
PM
Peak Hour
Meridian/Main
and
Waltman/Central
Traffic Signal
Intersection
LOS C D
Intersection
Delay (s/v) 28.4 36.0
Intersection
v/c 0.58 0.77
Worst Lane
Group LOS F (EBR) F (WBR)
Table 17 – Lane Group v/c Ratio – 2022 Total Traffic Intersection Signal Controlled
Intersection Approach
AM Peak Hour PM Peak Hour
LT THRU RT LT THRU RT
Meridian/Main
and
Waltman/Central
NB 0.78 0.63 0.40 0.89 0.83 0.36
SB 0.81 0.41 0.03 0.87 0.73 0.13
EB 0.21 0.14 0.88 0.21 0.11 0.82
WB 0.54 0.07 0.80 0.91 0.10 0.87
Mitigation
The westbound movement on Central Drive will operate at LOS F in the PM peak hour. This movement
already has two lanes. The north and south bound through movements have three lanes. There is not
much that can be done to mitigate this intersection. The overall intersection operation is acceptable. The
LOS of the turn movements could be improved by adjusting the timing, but the overall delay at the
intersection would increase.
Cut Through Traffic
Traffic from the Tanner Creek subdivision will mostly want to travel east of the site to access the
transportation system. A small percentage of the site traffic will use existing roads of the subdivision to
the west. As discussed above, the new roadway connection to Waltman will result in traffic from the
existing subdivision to divert to Waltman. This is not cut through traffic but will result in higher traffic
volumes on some existing roadways. Table 8 indicates that none of the local roads will experience daily
traffic volumes above 1,000 trips per day, therefore the peak hour volume should be less than 100, except
Muscovy Avenue and Pelican Drive may experience a volume of 100 vehicles during the PM peak hour.
According to section 5104.2.5 of the ACHD Development Policy Manual, volumes need to be greater
than 100 vehicles per hour to meet the threshold for traffic calming. The Manual also recommends that
the minimum length of a road segment be 750 feet to be considered for traffic calming. Pelican Drive,
Honker Drive, and Eider Drive will meet this criterion, but Muscovy Avenue will not. Honker Drive and
Eider Drive are non linear roadways, which will calm traffic. It is recommended that a speed study be
conducted on Pelican Drive to determine if traffic calming measures are warranted due to speed issues.
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Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
20
Site Access and Circulation
Figure 8 summarizes the estimated ADTs on the internal roadways and proposed access locations on
Waltman Lane. All proposed internal roadways are projected to carry a maximum of 636 vpd, which
meet ACHD’s maximum allowable ADT of 1,000 vpd on new local streets. The entrance to the
apartment complex will carry 1800 vehicles per day.
The Waltman Lane functions as a collector street with a posted speed limit of 25 mph, which requires the
following access spacing per ACHD Policy, Section 7206.4.5:
330 feet minimum separation for local streets
245 feet minimum driveway separation for more than 200 ADT
150 feet minimum driveway separation for less than 100 ADT
The proposed access points are separated by 750 feet, and it is 650 to the next approach. The proposed
access points meet the ACHD policy for separation.
Figure 8 – Proposed Access Locations and Internal Roadway ADTs
Apartment
Entrance
Ruddy Dr.
750’
636
230
200
1800
650’
Ruddy Dr
Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
21
The proposed driveways are located in a generally flat and straight segment of Waltman Lane and are
expected to have adequate sight distance for the 25 mph posted speed limit. Building setback and
landscaping should be located and designed to ensure adequate intersection sight distance.
Turn lane warrant was evaluated for the proposed site access intersections using ACHD guidelines – see
the appendix for turn lane warrant worksheets. The proposed site access intersections are not expected to
warrant turn lanes.
Table 18 summarizes site access intersection capacity analysis results. All site access intersections are
expected to operate at LOS B or better during the peak hours with 2022 total traffic.
Table 18 – Site Access Intersection Level of Service – 2022 Build-Out Year Total Traffic
Intersection Control MOEs
AM Peak
Hour
PM Peak
Hour
Waltman Lane
And Ruddy
Stop
(NB Approach)
LOS
(NB) A A
Delay (s/v)
(NB) 9 9
Worst Lane
Group LOS A (NB) A (NB)
Waltman Lane
and
Apartment
Entrance
Stop
(NB Approach)
LOS
(NB) A A
Delay (s/v)
(NB) 9 8
Worst Lane
Group LOS A (NB) A (NB)
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Traffic Impact Study
Tanner Creek Subdivision
Meridian, Idaho
March 2018
A
APPENDIX
SCOPE AND COMPASS AREA OF INFLUENCE RESULTS
TRAFFIC COUNTS
CRASH DATA
SYNCHRO REPORTS
TURN LANE WARRANT WORKSHEETS