HomeMy WebLinkAbout20 - Design Report - Bridger View PUD - RoadEngineering Report
Road Design
Bridger View PUD
October 2020
Submitted to:
City of Bozeman Engineering Department
20 East Olive
Bozeman, MT 59715
Prepared by:
Stahly Engineering and Associates
851 Bridger Drive, Suite 1
Bozeman, MT 59715
(406) 522-8594
Road Design 1 10/7/2020
Engineering Report
Table of Contents
General Information
Description of Travel Paths
Trip Generation
Pavement Design
Signage and Striping
Lighting
Figures and Tables
Figure 1. Vicinity Map
Figure 2. Paving Plan (Plan Sheet C 4.0)
Figure 3. Turning movement analysis
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General Information
The proposed Bridger View Planned Unit Development (PUD) is located southwest of
the intersection of Bridger Drive (MT 86) and Story Mill Road. Bridger View PUD is a 62-
home neighborhood consisting of modest homes with a compact, urban design. This
project is located on approximately 8 acres which was formerly occupied by 40 mobile
homes within the Bridger View Trailer Park. The proposed individual lots are compact,
and the subdivision streets are “right” sized to slow vehicles and make the streets safer
for residents, bikes, and pedestrians. The intent of the PUD is to create a walkable
neighborhood where pedestrian travel is emphasized.
The location of the Bridger View PUD site is shown on the Vicinity Map in Figure 1.
The developer’s contact information is:
HRDC
Heather Grenier
32 South Tracy Ave.
Bozeman, MT 59715
Figure 1: Vicinity Map, Bozeman, Montana
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Description of Travel Paths
Summary
Within the context of the project there is a hierarchy of travel paths. Bridger Drive, an
arterial street, is adjacent to the site to the north. Story Mill Road, a collector, is located
to the east of the site, with a linear park located between the site and the street. An
extension of Hillside Lane, a local city street, will run along the southern portion of the
site. Within the site small, association-maintained, woonerf streets and woonerf alleys
will provide access to the lots. The interior streets will access Bridger Drive at the
northwest, and Hillside Lane at the southwest and southeast areas of the site.
Preliminary plans are provided showing location and proposed street sections for
Hillside Lane and the interior woonerf streets and alleys.
Adjacent Arterial and Collector – Bridger Drive and Story Mill Road
Bridger Drive was recently upgraded by Montana Department of Transportation to
include sidewalks, bike lanes, two travel lanes and a center turn lane. Story Mill Road is
planned to be improved by two projects on the City of Bozeman Capital Improvements
Plan (CIP). CIP project SIF 116 consists of intersection improvements at the
intersection of Bridger Drive and Story Mill Road. CIP project SIF 117 consists of
improving Story Mill Road from Bridger Drive to Griffin Drive to a collector standard.
Both projects are currently scheduled for FY 2021 and will dramatically improve the
street network in this area.
Local City Street – Hillside Lane
Hillside Lane is planned to be extended with this project from Story Mill Road, across
the linear park and through the southern portion of the site to the western boundary of
the project. Hillside Lane is designed in accordance with City standards and planned to
be a 35’ wide (back of curb to back of curb) local City street. Stormwater mitigation for
Hillside Lane will be with boulevard bio-retention. The right-of-way is proposed to be 64’
wide allowing boulevards on each side to be two feet wider than typical to
accommodate the bio-retention. No individual driveways are proposed from Hillside
Lane.
Interior Woonerf Streets – Blue Silos Way, Millworks Way and Flourhouse Way
To provide an emphasis on pedestrian travel, interior streets are proposed to be
woonerfs, or shared streets, that are inviting to residents for walking or biking. where
pedestrian travel is accommodated along with the vehicle travel. To encourage slower
and non-motorized circulation, the asphalt street paving is edged on both sides by
concrete sidewalks without a curb. The interior woonerf streets are planned to be a 26’
surface with 5’-wide flush concrete bands along each edge and a 16’ asphalt center.
Woonerfs are located within a 30’ public right-of-way, owned and maintained by the
owners’ association. The woonerfs will provide fire lanes through the site and no parking
Road Design 4 10/7/2020
will be allowed on the woonerfs. A deviation from the City Design standards is
requested for the interior woonerf streets as allowed by the PUD.
Alley Woonerfs
Two alley woonerfs provide access to the rear of the lots and parking courts (shared
garages). The 23’-wide alley woonerfs are located within 25’ wide common open space
lots that have public access easements as shown on attached Figure 2.0. At the
driveways, a 1’ connection or driveway extension will provide the required 24’ backing
distance.
Sidewalks and Pathways
A network of sidewalks and pathways run through common open spaces providing
multiple pedestrian paths in addition to the woonerfs. Furthermore, connections to the
“Path to the M” and the Story Mill Spur Trail have been provided, allowing pedestrian
access to the larger community. Some sidewalks are widened to 12’ and reinforced to
provide access to utilities, or emergency vehicles.
Traffic Calming
A variety of traffic calming techniques are proposed in order to keep vehicle speeds low
on the interior woonerf streets. Principally, the narrow width will provide the most
significant traffic calming. The narrow width will be emphasized with building porches
extending towards the street. Where porches are not present, street trees along the
edges of woonerf will continue to emphasize the narrow width. Additionally,
intersections are stop controlled and kept as narrow as possible to reduce speeds. Also,
intersections and pedestrian crossings are proposed with concrete to stimulate driver
caution. A raised pedestrian crossing or tabletop is proposed where Blue Silos Way
crosses the Path to the M Trail.
To ensure that traffic calming does not prevent emergency vehicle access, a turning
movement analysis is provided on Figure 3 at the end of this report. This analysis
shows that a large fire truck can navigate through the site on the proposed road
surfaces and the vehicle overhang is within the right-of-way and/or between building
faces.
Traffic Generation
A Traffic Impact Study (TIS) has been conducted by Marvin & Associates and is
provided in a separate appendix. The TIS shows that all project accesses function at a
level of service C or better. The TIS also analyzes nearby intersections for level of
service. The intersection of Bridger Drive and Story Mill Road will function at a level of
service C after the addition of the traffic generated by this project. However, with the
projected growth in traffic within the next 15 years, this intersection will fall below a level
of service C, with or without this project. Because intersection improvements are
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proposed within the Capital Improvements Plan within the next 3 years, a waiver from
the intersection level of service requirements is requested.
Pavement Design
The Geotechnical Report provided in a separate appendix provides pavement design
for the project streets in accordance with City of Bozeman Standards. This analysis is
conducted in accordance with AASHTO Flexible Pavement design standards. The
analysis is based on a soil California Bearing Ratio (CBR) of 3.0 and equivalent single
axle loadings (ESAL) of 50,000 for the design life of the street. Both values are
conservative estimates, resulting in a long life. This analysis results in a total pavement
section of 18” over a geotextile fabric. The required pavement section consists of 9” of
sub-base gravel, 6” of crush road base gravel, and 3” of asphalt. Traffic-rated,
reinforced concrete will have a similar section, but with 3” of crushed road base gravel
and 6” of reinforced concrete for the upper materials.
However, for constructability the owner desires the sub-base gravel road to provide all-
weather construction access. The sub-base section has been increased from the
required minimum 9” to 18”, to provide suitable all-weather construction access prior to
pavement completion. This has the added benefit of increasing the road life beyond the
typical 20-year design, substantially reducing future maintenance costs. Plans are
provided showing the road construction details.
Signage and Striping
Proposed street signage is in accordance with the Manual of Uniform Traffic Control
Devices (MUTCD). Proposed street signage is shown in the plans provided with the
infrastructure submittal. Proposed signage consists of stop signs at intersections, street
name signs, woonerf signs to identify shared streets, and no parking signs for
intersections, fire lanes, and loading zones. Warning signs are proposed at the
entrances to the parking courts to warn visitors that these parking areas are for
residents only.
The Path to the M trail crossing is signed and striped to warn vehicles that pedestrians
may be crossing. Because Hillside Lane provides guest parking, an on-street accessible
parking space is proposed at the west end of Hillside Lane, to provide accessible
parking for visitors.
Lighting
Street lighting is proposed for Hillside Lane conforming to City standards, with proposed
streetlight fixtures at the two approaches to Hillside Lane. On-site lighting will be
provided by a combination of building-mounted and 12’ pole-mounted lights. The on-site
lighting provides interior street lighting as well as common area site lighting. On-site
lighting will be owned and maintained by the owners’ association.
PHASE 1PHASE 3PHASE 1PHASE 2PHASE 1PHASE 2PHASE 2PHASE 3STORY MILLSPUR TRAILSTORY MILL COMMUNITY PARKCITY OFBOZEMANPROPERTYSTORY MILL ROAD (60' ROW & 30' ESMT)BRIDGER DRIVE (Aka Hwy 86) - (110' ROW)HILLSIDE LANE(60' ESMT)HILLSIDE LANE (64' ROW)FLOURHOUSECOURTMILLWORKSCOURTHILLSIDE GREENHILLSIDE GROVEPHASE 2PHASE 3PATH TO THE "M"PARKSIDE WALKMILLWORKS ROW
FLOURHOUSE WAY (30' ROW)BLUE SILOS WAY (30' ROW)BLUE SILOSCOURTMILLWORKS WAY (30' ROW)ADDITIONAL ROW 1976 SFPAVING LEGENDASPHALT(TRAFFIC RATED)CONCRETE SIDEWALKCONCRETE DRIVEWAYSCONCRETE(TRAFFIC RATED)PAVERS(TRAFFIC RATED)ARCHITECTURAL JOINTINGCONCRETE (TRAFFIC RATED)C4.0PAVING PLANPROFESSIONALENGINEERS &SURVEYORSBRIDGER VIEW STAHLYENGINEERING& ASSOCIATESHRDC BOZEMAN MONTANA
TURNING ANALYSIS CRITERIACITY OF BOZEMAN FIRE TRUCKSPH 100 AERIAL PLATFORMTOTAL LENGTH - 46'WIDTH - 8' 2"WHEEL BASE - 230"OVERHANG PATHWHEEL PATHCENTERLINE WITH DIRECTIONFIGURE 3TURNINGMOVEMENTANALYSISPROFESSIONALENGINEERS &SURVEYORSBRIDGER VIEW STAHLYENGINEERING& ASSOCIATESHRDC BOZEMAN MONTANA