PZ - Traffic Impact Study (2)Thompson
Traffic and Civil 14k,
Engineers
Inc.
EXECUTIVE SUMMARY
Traffic Impact Study
Stapleton Subdivision - Meridian, Idaho
Thompson Engineers, Inc. has been retained to prepare a traffic impact study (TIS) for the proposed Stapleton
Subdivision located southwest of the Harris Road and Meridian Road (SH 69) intersection in Meridian, Idaho, as
shown in Figure 1.1. The scope of this study was determined through coordination with the Idaho Transportation
Department (ITD).
The TIS evaluates the potential traffic impacts resulting from background traffic growth, off-site developments in
the area, the proposed development, and identifies improvements to mitigate the impacts. Traffic impacts were
evaluated under the following traffic conditions:
■ 2018 Existing traffic
■ 2021 Phase 1 background traffic
■ 2021 Phase 1 total traffic
■ 2025 Build -out background traffic
■ 2025 Build -out total traffic
1.0 Proposed Development
1.1 At full build -out, Stapleton Subdivision is estimated to include a total of 223 single-family dwelling units.
The development is planned to be developed in four separate phases. Phase 1 contains 53 dwelling units with
an expected 2021 build year. Full build -out is projected to occur in 2025 but may change depending on the
market conditions.
1.2 Based on the Institute of Transportation Engineers (ITE) Trip Generation Manual 10' Edition, Stapleton
Subdivision is estimated to generate approximately 2,106 trips per weekday, 166 trips during the AM peak
hour, and 223 trips during the PM peak hour at full build -out.
■ The development is not expected to retain trips within the site or generate pass -by trips
■ All trips generated by the subdivision were assumed to be made by personal or commercial vehicles
■ The estimated site traffic distribution patterns are:
• 70% north of the site
• 15% west of the site
• 10% east of the site
• 5% south of the site
1.3 Stapleton Subdivision is proposing one site access approach on SH 69 in Phase 1 and one additional site
access approach on Harris Street for full build -out conditions:
■ Solaris Street on SH 69
• Locate approximately 1,340 feet south of Harris Street
• Meets IDAPA access spacing for full access public road in both transitional and urban conditions
• Requires a southbound right -turn lane based on ITD guidelines with Phase 1
■ Beeler Drive onto Harris Street
• Locate approximately 1,350 feet west of Meridian Road
• Meets ACHD minimum access spacing on Harris Street, a 20 -mph collector street
1.4 The proposed internal roadways are expected to carry less than 1,000 vpd at full build -out along the roadways
that have front -on housing. Beeler Drive northwest of Hyndman Street is expected to exceed 1,000 vpd but
not exceed 2,000 vpd. This segment Beeler Drive does not have front -on housing.
1.5 Based on the expected volumes on the internal roadways and site access operations, a backage/collector
street is not needed to improve the site circulation.
December 2018
ThompsonEngineers Traffic Impact Study
Traffic and Civil 14k Inc. Stapleton Subdivision - Meridian, Idaho
2.0 Improvements Needed to Mitigate 2018 Existing Traffic
2.1 The Meridian Road and Harris Street intersection exceeds ITD's acceptable level of service (LOS) D
threshold during the PM peak hour analyzed with the existing intersection control and lane configurations.
The Harris Street approaches currently carry low volumes and are operating under capacity with low v/c
ratios during the peak hours. The Meridian Road and Harris Street intersection is planned to be signalized
based on previous traffic impact studies prepared for the proposed off-site developments in the area.
However, the intersection does not meet warrants for a traffic signal with the current volumes. As a result,
no improvements are recommended to mitigate 2018 existing traffic.
3.0 Improvements Needed to Mitigate 2021 Phase 1 Background Traffic
3.1. The Meridian Road and Harris Street intersection is expected to exceed ITD's acceptable LOS D threshold
with 2021 background traffic analyzed with the existing intersection control and lane configurations during
the PM peak hour. The Harris Street approaches are expected to operate under capacity with v/c ratio of 0.53
or less during the peak hours. The intersection is not expected to meet warrants for a traffic signal with the
2021 background traffic projection. As a result, no improvements are recommended to mitigate 2021
background traffic.
4.0 Improvements Needed to Mitigate 2021 Phase 1 Total Traffic
4.1 The Meridian Road and Harris Street intersection is expected to exceed ITD's acceptable LOS D threshold
during the PM peak hour with 2021 total traffic analyzed with the exiting intersection control and lane
configurations. The minor approaches are expected to continue to operate under capacity with a v/c ratio of
0.56 or less during the peak hours. The intersection is not expected to meet warrants for a traffic signal with
the 2021 total traffic projection. As a result, no improvements are recommended to mitigate 2021 total traffic.
4.2 The Meridian Road and Solaris Street intersection is expected to exceed ITD's acceptable LOS D threshold
as a stop -controlled intersection during the PM peak hour. The Solaris Street approach is expected to operate
under capacity with a v/c ratio of 0.24 or less during the peak hours. Based on ITD's right -turn lane
guidelines, a southbound right -turn lane is needed with 2021 Phase 1 total traffic.
5.0 Improvements Needed to Mitigate 2025 Build -Out Background Traffic
5.1 The Meridian Road and Harris Street intersection is expected to exceed ITD's minimum operational
thresholds with 2025 background traffic volumes analyzed with the existing intersection control and lane
configurations. The intersection is expected to meet signal warrants for a traffic signal and is recommended
to mitigate 2025 background traffic.
6.0 Improvements Needed to Mitigate 2025 Build -Out Total Traffic
6.1 The Meridian Road and Harris Street intersection is expected to meet ITD's minimum operational thresholds
with 2025 build -out total traffic conditions analyzed as a signalized intersection with the existing lane
configurations. As a result, no additional improvements are needed to mitigate 2025 build -out total traffic
impacts.
6.2 The Meridian Road and Solaris Street intersection is expected to meet ITD's minimum operational
thresholds with 2025 build -out total traffic as a stop -controlled intersection.
December 2018 4