Citywide Traffic Signal Re-Timing
Washington, DC - 2015


  • Signal Timing Optimization
  • Data Collection
  • Traffic Modeling
  • Traffic Operations and Analysis
  • GIS Database



Sabra & Associates, Inc. (SAI) performed traffic signal timing optimization for all 1,600+ signalized intersections within the District of Columbia. The goal of the optimization project was to make DC traffic signals safer and friendlier for the pedestrians, improve bus running times & reduce bus delays, improve overall traffic flow and reduce vehicular traffic emissions. The work included:


  • Design and development of an on-line GIS database of signalized intersections, zone boundaries, travel time routes, bus routes, Ward boundaries, PCN and links to pdfs of traffic counts to share information among DDOT and the SWA Team
  • Before and After Travel time and delay studies with GPS
  • Intersection geometric inventory, including parking restrictions, bus stop frequencies and corner circulation areas for use in pedestrian Level of Service analyses
  • Video intersection traffic data collection
  • Analysis of TOD patterns for daily signal timing plans
  • Synchro model development
  • Analysis of Y, AR, W, FDW intervals
  • Development of software to automate the Change and Clearance interval calculation process and display print-outs of intersection distance measurements and phase assignments for record-keeping
  • Conversion from 215 Interval to 233 Phase Controller firmware
  • Design of TS Drawings and Dial Sheets
  • Development of optimized signal timing plans for 5 patterns: AM, Midday, PM, Nighttime and Weekend, implementation and field fine-turning
  • Benefit cost analysis; development of final reports

7055 Samuel Morse Dr., Ste. 100
Columbia, MD 21046
443-741-3500 | F: 443-741-3700

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