traffic signal optimization: a coordinated effort tom dancey, p.e. signal system engineer city of...
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TRAFFIC SIGNAL OPTIMIZATION:A Coordinated Effort
Tom Dancey, P.E.
Signal System Engineer
City of Springfield
CITY OF SPRINGFIELD &MISSOURI DEPARTMENT OF TRANSPORTATION
Springfield
Where?
Population: 155,000
Regional Hub for • Employment
• Retail
• Medical
• Serving 380,000+
7,000,000 Visitors to the Springfield/Branson Region
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CITY139
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MoDOT108
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247 Signalized Intersections
The Need to Coordinate
Combined Signal System
Acquired Common Firmware
Unified Central Software
Adopted Common Controller (170E) and Cabinet Standards
Expanded Shared Communications Infrastructure
Transportation Management Center
City and State Personnel Work Side-by-Side
• Monitor Traffic/Signal System
• Incident Response
• Special Events
• Traveler Information
Equal Access to Signal System
Equal Access to CCTV Monitoring System
Separate Maintenance but Shared Responsibility for Ongoing Operations
Data Collection
System Detectors (loops and video)
Link Volumes (temporary counters) (collected every 4 years on rotation)
Manual Turning Movement Counts (collected every 4 years on rotation)
Data Collection
Travel Time Runs• Travel Time• Delay• Number of Stops• Travel Speed
Identify Problem Areas Baseline for
Evaluation of Signal Operations
Goal: “Maximize two-way progression with
the most efficient cycle length to
minimize overall delay”
Reality: “Do the best you can within the constraints of the laws of physics”
Optimization/Timing Plan Development
Compare Volumes by Location and Day-of-Week
Determine Number of Plans and Time Periods
Determine Coordination Grouping
Optimization/Timing Plan Development
Build Analysis Model (geometric data)
Calibrate Model to Existing Conditions (understand output)
Load Volume Data and Determine Peak Volume
Optimization/Timing Plan Development
Identify Optimal Cycle Length for Each Intersection Review Coordination Grouping Agree/Compromise on Common Cycle Length
Optimization/Timing Plan Development
Optimize Splits for Each Intersection
• Consider Minimums, Pedestrian Clearance, Phase Omits
• Estimate in Absence of Counts
Optimization/Timing Plan Development
Identify the Master Intersection for Each Plan
(Two Highest Priority Corridors)
Optimization/Timing Plan Development
Optimize Two-Way Progression • Use Posted or
Observed Speeds
• Use Model Output as a “Start”
• Phase Order and Offset Adjustments (Not just for Arterial Band)
• Minimal Splits for Lagging Left Turns
• Be Mindful of Actuation
• Control Platoon Speed
• Clear Queues Ahead of Platoon if Possible
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Program the Signal System
Translate into Signal Software
Understand Software Requirements
• Permissive Period
• Sync Phases
• Phase Order
• Max Limits
• etc.
Consider Use of Test Controller
“Fine Tune” the Plan Observe Entire System
• Corridors
• Individual Intersections
Utilize CCTV System
Continue Making Adjustments
Evaluate the Plan
Compare New Travel Times to “Before”
Evaluate the Plan Ratio of Actual Travel Time to
Calculated Free-Flow Travel Time
For More Information:
Tom Dancey, P.E.
Signal System Engineer
City of Springfield
CITY OF SPRINGFIELD &MISSOURI DEPARTMENT OF TRANSPORTATION
Laurel McKean, P.E.
Assistant Traffic Operations Engineer
Missouri Department of Transportation