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TRANSCRIPT
Simulation Analysis of Intersection Treatments for
Cycle Tracks
David Stanek, PE and Charles Alexander, PE, AICP
ITE Western District Annual Meeting
Las Vegas, NV – July 2015
Conventional Bike Lane Design
Bike lane on J Street in Sacramento, CA Source: Fehr & Peers
Typically to the left of parked cars and to the right of travel lanes.
Cycle Tracks
“…an exclusive bikeway that combines the user experience of a separated path with the on-street infrastructure of a conventional bike lane.”
-NACTO Urban Bikeway Design Guide
A one-way cycle track in Chicago, IL Source: Chicago DOT
Conventional Intersection Designs
With right turn pocket lane Source: California MUTCD
With parking lane turning into a right turn lane Source: California MUTCD
Mixing Zone
Merge bicyclists into bike lane or shared lane in advance of intersection
A mixing zone in Washington D.C. Source: Streetsblog
A mixing zone in New York City Source: NACTO
Exclusive Turn Phase
• Provides separate signal phases for turning drivers and through bicyclists
• Potential capacity tradeoffs
An exclusive turn phase at a cycle track in New York City Source: NACTO
Protected Intersection
Corner refuge islands provide key features for bicyclists:
• Advanced stop bars
• Set back crossings
• Two-stage left turns
• Free right-turns
Borrows from Dutch intersection designs
Conceptual design of a protected intersection Source: Vimeo
Scheduled for Construction
Salt Lake City, UT Source: Streetsblog
Davis, CA Source: Carlson, Barbee & Gibson, Inc.
Signal Operation
Options:
1. Right turn vehicles yield to bicycles
2. Bicycles have a leading interval phase
3. Bicycles have a scramble phase
4. Right turn vehicles have protected phase and bicycles proceed with through vehicles
Signal control of cycle track will affect intersection operations for all users.
Source: California MUTCD
Analysis Model
Vissim microsimulation networks
Conventional Intersection Protected Intersection
Model Assumptions
• Seeding interval of 15 minutes, peak 15 minutes of one hour period
• Peak hour factor of 0.95, 3 percent heavy vehicles
• Pedestrian volume of 20 per hour each direction in crosswalks
• Average speeds: 25 mph for vehicles, 11.5 mph for bicycles, and 2.5 mph for pedestrians
• Turn pockets of 150 ft for major street left and 100 ft for major street right and minor street left
• Protected left turns for major street and permissive for minor street
• Maximum recall for major street through and actuated for others
Turning Movement Volumes
Mode Volume (vph)
Motor Vehicles 2,400
Bicycles 320
Pedestrians 160
Total 2,880
Conventional Intersection
• Right turns on red are allowed
• Mixing zone upstream of right turn lanes
• Bicycles use left turn lanes
Conventional Intersection
Mode Delay (sec)
Motor Vehicles 53.5
Bicycles 25.4
Pedestrians 42.8
Total 51.2
Option 1 – Right Turn Yield
For all options:
• Right turns on red are not allowed
• Bicycles use cycle track network only
• Bicycles make two-stage left turns
Option 1 – Right Turn Yield
Mode Delay (sec)
Motor Vehicles 40.5
Bicycles 28.1
Pedestrians 41.8
Total 40.3
Mode Delay (sec)
Motor Vehicles 53.5
Bicycles 25.4
Pedestrians 42.8
Total 51.2
Conventional Intersection
Option 2 – Leading Interval
• 5-second leading interval phase for bicycles and pedestrians
• Leading interval occurs before through/right turn phases
• Cycle length increased from 90 to 100 seconds
Option 2 – Leading Interval
Mode Delay (sec)
Motor Vehicles 64.3
Bicycles 28.1
Pedestrians 40.3
Total 60.6
Mode Delay (sec)
Motor Vehicles 53.5
Bicycles 25.4
Pedestrians 42.8
Total 51.2
Conventional Intersection
Option 3 – Scramble Phase
• 25-second exclusive phase for bicycles and pedestrians
• No bicycles or pedestrians during other phases
• Minor street phases reduced from 30 to 25 seconds
• Cycle length increased from 90 to 110 seconds
Option 3 – Scramble Phase
Mode Delay (sec)
Motor Vehicles 103.8
Bicycles 31.2
Pedestrians 47.4
Total 95.2
Mode Delay (sec)
Motor Vehicles 53.5
Bicycles 25.4
Pedestrians 42.8
Total 51.2
Conventional Intersection
Option 4 – Right Turn Phase
• 15-second lagging phase for major street rights
• Minor street phases reduced from 30 to 25 seconds
• Shift of 5 seconds from WB through to EB left
• Cycle length increased from 90 to 100 seconds
Option 4 – Right Turn Phase
Mode Delay (sec)
Motor Vehicles 66.6
Bicycles 29.5
Pedestrians 45.5
Total 63.1
Mode Delay (sec)
Motor Vehicles 53.5
Bicycles 25.4
Pedestrians 42.8
Total 51.2
Conventional Intersection
Signal Phasing
Conventional & Right Turn Yield
Leading Interval
Scramble Phase
Right Turn Phase
Results Summary
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Pedestrians
Results Summary
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Results Summary
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Conventional Right Turn Yield Leading Interval Scramble Phase Right Turn Phase
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Bicycles Pedestrians Motor Vehicles Total
Findings
• Simulation analysis can determine delay by mode
• Protected intersection can have lower delay for motor vehicles • Using standard signal phasing
• Due to removing bicycles and shorter crosswalks
• Delay would increase for motor vehicles with Leading Interval and Right Turn Phase options
• Scramble Phase option would have highest delay for all modes
• All options increase bicycle delay due to two-stage left turns
• Pedestrian delay is similar across options
Simulation Analysis of Intersection Treatments for
Cycle Tracks
David Stanek, PE and Charles Alexander, PE, AICP
ITE Western District Annual Meeting
Las Vegas, NV – July 2015