HomeMy WebLinkAbout02-02-15 Traditions Traffic Impact Study traffic Traffic Impact Study
services Traditions Subdivision Phases 2 & 3
Residential Development
Bozeman, Montana
Prepared For:
Rosa Construction
209 Black Bull Trail
Bozeman, MT 59718
September, 2014
130 South Howie Street
Helena, Montana 59601
_ 406-459-1443
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Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Table of Contents
A. Executive Summary......................................................................................I
B. Project Description........................................................................................1
C. Existing Conditions........................................................................................I
AdjacentRoadways..............................................................................2
TrafficCounts........................................................................................3
Additional Developments.......................................................................3
Levelof Service.....................................................................................3
D. Proposed Development..............................................................................4
E. Trip Generation and Assignment................................................................4
F. Trip Distribution ..........................................................................................6
G. Traffic Impacts Outside of the Development...............................................6
H. Impact Summary & Recommendations......................................................7
List of Figures
Figure 1 — Proposed Development Site...................................................................2
Figure 2— Proposed Development..........................................................................5
Figure3— Trip Distribution......................................................................................6
List of Tables
Table 1 — 2013 Level of Service Summary..............................................................3
Table 2— Trip Generation Rates.............................................................................4
Table 3— Level of Service Summary With Development........................................7
i
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Traditions Subdivision Phases 2 & 3
Traffic Impact Study
Bozeman, Montana
A. EXECUTIVE SUMMARY
The Traditions Subdivision Phases 2 & 3 is a 21 acre residential development located west of
Cottonwood Road. The project would include up to 98 new residential units. As proposed, the
development will not create any new roadway capacity problems along Durston Road. The
intersection of Durston Road and Cottonwood Road is currently operating at a poor LOS in the
PM peak-hour and the traffic from this development will add to this problem. The planned four-
way STOP control at this intersection will add additional capacity but will not be a long-term
solution. It is recommended that the developers participate in the reconstruction of this
intersection once a design has been finalized. All other nearby intersections will continue to
function at acceptable levels of service and no other additional improvements will be required
along Durston Road to serve the proposed development.
B. PROJECT DESCRIPTION
This document studies the possible effect on the surrounding road system from a proposed
residential development located north of Annie Street and west of Cottonwood Road in
Bozeman, Montana. The document also identifies any traffic mitigation efforts that the
development may require. The property would be developed to include up to 98 new residential
units. Based on the City of Bozeman Subdivision Regulations, the developers must study all
effected intersections within 'h mile of the proposed development which includes the
intersections of Durston Road with Laurel Parkway, Rosa Way, Cottonwood Road, and Flanders
Mill Road. Although this development will include the construction of a portion of Oak Street,
the section of road will not connect to the existing sections of Oak Street to east and will not
provide access to the development site until additional properties in this area are developed to the
east.
C. EXISTING CONDITIONS
The proposed development property currently consists of a 21-acre parcel of undeveloped land
located north of Annie Street and west of Twin Lakes Avenue just east of the new Boulder Creek
Subdivision and west of the existing Traditions Subdivision. The topography in this area is flat.
See Figure 1 for a location map of the proposed development.
Abelin Traffic Services 1 September 2014
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Figure 1 Proposed Development Site
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Adjacent Roadways
Durston Road is a two-way east/west minor arterial route that provides access to the
residential areas to the west of Bozeman. In recent year much of the road has been
reconstructed to accommodate development in this area. Currently the road has a three-lane
cross-section with a paved width of 46-feet east of Cottonwood Road and two-lanes paved at
31 feet west of Cottonwood Road. Durston Road also has designated bike lanes. All cross-
street between Laurel Parkway and Flanders Mill Road are controlled by STOP signs. The
roadway has a posted speed limit of 35 MPH and currently carries 7,800 Vehicles Per Day
(VPD).
Laurel Parkway is a north/road that was constructed to serve the different phases of the
Laurel Glen development. This roadway was constructed with a wide median, turn lanes,
and roundabouts at some intersection to provide capacity for future development and future
road connections. The roadway has a posted speed limit of 25 MPH and currently carries
2,800 Vehicles Per Day(VPD).
Cottonwood Road is a principal arterial north/south route that provides access to the
residential developments to the north and Huffine lane to the south. The road has a two-lane
cross-section with a paved width of 28-feet near Durston Road. The road has a posted speed
limit of 25 MPH north of Durston Road and 40 MPH south of Durston Road. Cottonwood
Road currently carries 550 VPD north of Durston Road. .
Flanders Mill Road in a north/south two-lane road which provides access north to Baxter
Lane. The road currently has a paved width of 27 feet and a posted speed limit of 40 MPH.
Flanders Mill Road currently carries 2,500 VPD north of Durston Road.
Abelin Traffic Services 2 September 2014
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Traffic Counts
In July 2013 Abelin Traffic Services (ATS) collected turning movement count data at
intersections along Durston Road as part of the Boulder Creek/Westbrook development
projects. These counts included the intersections of Durston Road with Laurel Parkway,
Rose Way, Cottonwood Road, and Flanders Mill Road. ATS also collected 24-hour ADT
data on Laurel Parkway, Flanders Mill, and Durston Road. The raw traffic data is
included in Appendix A of this report.
Additional Developments
A variety of additional developments are currently in different stages of design and
construction within this area. The Boulder Creek and Westbrook developments are
underway just west of the Traditions Subdivision and will include 233 residential units.
Other developments in this area include the Norton Ranch development (270 residential
units), the J&D Family development (40 residential units) and a variety of apartment
complexes and commercial lots. The traffic from these projects was included in the
future traffic modeling for this report.
Level of Service
Using the data collected for this project, ATS conducted a Level of Service (LOS)
analysis at area intersections. This evaluation was conducted in accordance with the
procedures outlined in the Transportation Research Board's Highway Capacity Manual
(HCM) - Special Report 209 and the Highway Capacity Software (HCS) version 5.3.
Intersections are graded from A to F representing the average delay that a vehicle
entering an intersection can expect. Typically, a LOS of C or better is considered
acceptable for peak-hour conditions.
Table 1 —2013 Level of Service Summary
AM Peak Hour PM Peak Hour
Intersection Delay (Sec.) LOS Delay (Sec.) LOS
Durston Road & Laurel 14.4 B 13.3 B
Parkeway
Durston Road & Rosa 12.6 B 13.8 B
Way
Durston Road & 10.7 B 16.8 C
Cottonwood Road*
Durston Road & 11.3 B 16.8 C
Flanders Mill Road
*With Four-Way STOP control.
Abelin Traffic Services 3 September 2014
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Table 1 shows the existing 2013 LOS for the AM and PM peak hours without the traffic
from the proposed development. The LOS calculations are included in Appendix C.
Table 1 shows that the existing intersections along Durston Road are currently operating
within acceptable limits. This analysis assumes that the intersection of Cottowood Road
and Durston Road is modified to a four-way STOP controlled intersection as planned
with the Norton Ranch Subdivision.
D. PROPOSED DEVELOPMENT
The development currently under consideration for this site includes 21 acres of land located
north of Annie Street which would be developed into a residential subdivision. Phase 2 of the
Traditions Subdivision would include 34 homes and Phase 3 would include 64 homes for a total
of 98 new residential homes. The development would have designated parks and sidewalks
throughout the property. Access to the development site would be provided through new
connections to Annie Street and Twin Lakes Avenue. The Baxter Ditch runs along the west side
of the property. As this area continues to develop in the future it is likely that additional road
connections will be provided to the north and east. The Traditions Subdivision Phases 2 & 3
development is shown in Figure 2.
E. TRIP GENERATION AND ASSIGNMENT
ATS performed a trip generation analysis to determine the anticipated future traffic volumes
from the proposed development using the trip generation rates contained in Trip Generation
(Institute of Transportation Engineers, Seventh Edition). These rates are the national standard
and are based on the most current information available to planners. A vehicle "trip" is defined
as any trip that either begins or ends at the development site. ATS determined that the critical
traffic impacts on the intersections and roadways would occur during the weekday morning and
evening peak hours. According to the ITE trip generation rates, at full build-out the
developments would produce 74 AM peak hour trips, 99 PM peak hour trips, and 938 daily trips.
See Table 2 for detailed trip generation information.
Table 2 - Trip Generation Rates
AM Peak Total AM PM Peak Total PM
Hour Trip Peak Hour Trip Peak Weekday Total
Ends per Hour Trip Ends per Hour Trip Trip Ends Weekday
Land Use Units Unit Ends Unit Ends per Unit Trip Ends
Single-Family 98 0.75 74 1.01 99 1 9.57 1 938
Abelin Traffic Services 4 September 2014
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
Figure 2 -Traditions Subdivision Phases 2 & 3
PREUMINARY PLAT OF
TRADITIONS SUBDIVISION — PHASES 2 AND 3
LOCATED IN THE E 112 OF THE SE 114 OF SECTION I, T. 2 S., R. 5 E.
OF P.M.M., GALLATIN COUNTY, MONTANA
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Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
F. TRIP DISTRIBUTION
The traffic distribution and assignment for the proposed subdivisions was based upon the
existing ADT volumes along the adjacent roadways and the peak-hour turning volumes. Based
on field observations, half of the traffic from the development site will use Durston Road to
reach areas to the east in Bozeman. The rest of the traffic will use Cottonwood Road, Flanders
Mill Road, and Durston Road to reach other destinations. Traffic is expected to distribute onto
the surrounding road network as shown on Figure 3.
Figure 3 —Trip Distribution
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G. TRAFFIC IMPACTS OUTSIDE OF THE DEVELOPMENT
Using the trip generation and trip distribution numbers, ATS determined the future Level of
Service for the area intersections. The anticipated intersection LOS with the Traditions
Subdivision Phases 2 & 3 is shown in Table 3. These calculations are based on the projected
model volumes included in Appendix B of this report.
Table 3 indicates that the construction of the Traditions Subdivision Phases 2 & 3 will not cause
any new roadway capacity problems at locations along Durston Road. The intersection of
Cottonwood Road and Durston Road will need improvements to function at an adequate LOS
regardless of the construction of the Traditions Subdivision Phases 2 & 3. It should be noted that
it will take at least 3-5 years for all of the developments in this area to be completed and for
improvements to become necessary at this intersection.
There are several options for improving the capacity and LOS at the intersection of Durston
Road and Cottonwood Road. The capacity related issues at this intersection could be addressed
by constructing a traffic signal or modern roundabout at this location. If constructed, a
roundabout would operate at LOS B with 14.7 seconds of delay and would provide sufficient
Abelin Traffic Services 6 September 2014
Traditions Subdivision Phases 2 &3 Traffic Impact Study Bozeman,Montana
capacity for this intersection well into the future. If the intersection were constructed as a traffic
signal it would function at LOS B with 16.9 seconds of delay.
The City of Bozeman is currently in the planning stages of selecting a long-term improvement
for this intersection which will likely be a traffic signal or roundabout. The City is funding the
design for the intersection but has no current plans for construction funding. In this instance it
may be most appropriate for the developers to agree to pay for a portion of the construction of
the final design rather than taking additional steps to construct an interim fix for the intersection
that may not fit with the final design.
Table 3 —Level of Service Summary
With the Boulder Creek/Westbrook Developments
AM Peak Hour PM Peak Hour
Intersection Delay (Sec.) LOS Delay (Sec.) LOS
Durston Road & Laurel 15.5 B 14.2 B
Parkewa
Durston Road & Rosa 14.3 B 15.5 C
Way
Durston Road & 15.4 C 61.5 F
Cottonwood Road*
Durston Road & 12.5 B 22.5 C
Flanders Mill Road
*With Four-Way STOP control.
H. IMPACT SUMMARY & RECOMMENDATIONS
As proposed, the Traditions Subdivision Phases 2 & 3 development will not create any new
roadway capacity problems along Durston Road. The intersection of Durston Road and
Cottonwood Road is currently operating at a poor LOS in the PM peak-hour and the traffic from
this development will add to this problem. The planned four-way STOP control at this
intersection will add additional capacity but will not be a long-term solution. It is recommended
that the developers participate in the reconstruction of this intersection once a design has been
finalized. All other nearby intersections will continue to function at acceptable levels of service
and no other additional improvements will be required along Durston Road to serve the proposed
development.
Abelin Traffic Services 7 September 2014