Citywide Traffic Signal Re-Timing
Washington, DC - 2015

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:


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


  • 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 SAI 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


Columbia Maryland

7055 Samuel Morse Drive
Suite 100
Columbia, MD 21046
Phone: 443-741-3500
Fax: 443-741-3700

Baltimore Maryland
1502 Joh Avenue
Suite 100
Baltimore, MD 21227

Phone: 410-536-3653
Fax: 410-536-3654

Washington, D.C.

100 M Street SE
Suite 550
Washington, DC 20003

Phone: 202-570-7080
Fax: 202-697-5007

Vienna, Virginia

8150 Leesburg Pike
Suite 630
Vienna, VA 22182

Phone: 703-942-8990


2018 Sabra & Associates, Inc. | All rights reserved | Contact us