Thirty-Seven (37) Audible Emergency Preemption Systems Installed as Part of a Regional Traffic Signal Program (RTSP) Helped Reduce Emergency Response Time by 14 to 23 Percent.

Project partners presented safety and productivity benefits of improving signal control at 148 intersections across 15 corridors in Southwestern Pennsylvania.

Date Posted

Regional Traffic Signal Program: Cycle 3 Summary

Summary Information

Transportation Systems Management and Operations (TSMO) projects are gaining popularity due to their impressive return on investment. This study examined the benefits in the first year after installation of new signal hardware and corridor timing optimization via Southwestern Pennsylvania Commission (SPC)’s Regional Traffic Signal Program (RTSP) in Pennsylvania. Through the FHWA's Congestion Mitigation Air Quality Program (CMAQ) and contributions from participating local governments, SPC provided nearly $4 million in funding for a third cycle of the projects. These projects involved retiming 148 intersections across 15 corridors, primarily on state or US highways throughout Southwestern Pennsylvania between Summer 2018 and Spring 2019. Besides retiming, the improvements featured audible emergency vehicle preemption, signal controllers, new communication equipment, and GPS units for enhanced signal coordination. Countdown pedestrian signals were also introduced to improve pedestrian safety.


A benefit-to-cost analysis was performed for the first year after installation of the third cycle of projects. There were 148 signals upgraded across the 15 different corridors with AADT (Annual Average Daily Traffic) ranging from 6,200 to 34,700. Operation and safety benefits were estimated using the monetary value of the reduction in hours of vehicle delay, stops, gallons of fuel consumed, and harmful emissions (CO, NO, and VOCs).


  • The total retiming benefit for the first year was estimated at $26,611,509 with a benefit-to-cost ratio of 21:1. The highest benefit-to-cost ratio for a single corridor ranged from 2:1 to 51:1.
  • There was a significant reduction in travel time with a decrease of 1,320,281 vehicle-hours and 18,466,469 fewer stops, leading to savings of 976,044 gallons of fuel.
  • The total safety benefit for the first year was estimated at $29,593,877 with a benefit-to-cost ratio of 23:1.
  • Pedestrian safety was enhanced with 128 upgraded phases at 79 intersections and 12 Lead Pedestrian Intervals (LPIs) in Pittsburgh, supplemented by 168 countdown signals, leading to a 70 percent decrease in related crashes.
  • Moreover, 37 Audible Emergency Systems were introduced, reducing emergency response times by 14 to 23 percent.

The table below excerpted from the source report outlines the major project level reductions and their monetary value.

  Delay (hrs) Stops Fuel (gal) Emissions (kg) Total Benefit ($) Total Cost ($) B/C Ratio
Total 1,320,281 18,466,469 976,044 107,680 26,611,509 1,265,744 21:1