Poplar
PROJECT DISCUSSION
US 2 – POPLAR
APRIL 15, 2015
Project Overview
Roundabout
Slope Flattening
Surface
Rehabilitation
Surface
Rehabilitation
Roundabout
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What is Surface Rehabilitation?
Existing Roadway Surface
Existing curb
8” Pavement
18” Base Gravel
Proposed Roadway Surface Alternative
Existing curb
1.2” New Pavement Wearing Course
5” New Pavement
10” Recycled Cement-Treated
Base Gravel
Existing Base Gravel
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Other improvements…
2ND AVE. W SIGNAL UPGRADES
PROWAG-COMPLIANT ADA RAMPS
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Project Overview
Roundabout
Slope Flattening
Surface
Rehabilitation
Surface
Rehabilitation
Roundabout
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Why Consider Roundabouts?
• REDUCE CRASHES AND INJURIES
• Improve pedestrian accessibility
• Improve traffic mobility
• Reduce vehicle speeds
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Overview of Roundabouts
What is a Roundabout?
A roundabout is a circular intersection through
which vehicles travel counterclockwise around a
center island.
The geometric features of a roundabout create a
low-speed environment. Trucks will have to slow
to about 17 mph to go around the roundabout.
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Overview of Roundabouts
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All Travel Counter-clockwise
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Geometric Speed Reduction
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Vehicles Entering Must Yield
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Splitter Islands
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Mountable Truck Apron
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Pedestrian refuge
Aesthetics
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Roundabouts reduce crashes and
crash severity compared to a
traditional intersection
35%
ALL CRASHES
76%
INJURY CRASHES
90%
FATAL CRASHES
Benefits of a
roundabout
Increase safety
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Benefits of a
roundabout
Why are crashes
reduced by
Roundabouts?
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Benefits of a
roundabout
 Head-on and right-angle (T-bone) crashes virtually
eliminated.
Why is crash
severity
reduced with
Roundabouts?
 Vehicle speeds are reduced by geometrics instead
of signing or enforcement – vehicles, especially
trucks, simply cannot navigate roundabouts at high
speeds.
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Traditional Intersection
Roundabout
Benefits of a
roundabout
Increase pedestrian
safety
• Slower vehicle speeds allow for more time to cross.
• For pedestrians, median refuge islands and shorter
crossing distances increases safety.
• Fewer conflict points for pedestrians also.
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Roundabout Truck Accommodations
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Roundabout Truck Design Elements
• Flat cross slopes to limit load shift
• Low truck apron curb for low-boys
• Low center median curb for over-sized
loads
• Removable signs
• Traversable exterior sidewalk/boulevards
• Light poles and landscaping outside oversized truck paths
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Kirn Road Concept
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Median Island Concepts
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Airport Redevelopment Status
Proposed 5th Street Roundabout
Roundabout Considerations
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Strong Development Benefits
Frontage Road Impacts
Right of Way Needs
Bike Path Connections
Funding
Shane Mintz, PE
Montana Department of Transportation
406-345-8212
[email protected]
April Gerth, PE
Robert Peccia & Associates
406-447-5000
[email protected]
Steve Grabill LSIT, PE, PTOE
KLJ
406-441-5783
[email protected]
Questions?
KIRN ROAD PRELIMINARY R/W NEEDS
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5TH AVE. E PRELIMINARY R/W NEEDS
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