Automated traffic signal performance measures (ATSPMs) offer an alternative approach to traditional signal retiming. They are developed using second-by-second data that can be collected over several months or years. The Federal Highway Administration (FHWA) included ATSPMs in Every Day Counts 4, and since then, dozens of agencies have installed this new technology. ATSPMs have been shown to help agencies improve operations at signalized intersections through reduced split failures, arrivals on red, red-light running, and delay.
The right-of-way time that is allocated to different modes and movements can significantly impact behavior–drivers willing to take smaller gaps, pedestrians waiting for the walk signal, or bicyclists clearing an intersection. While not a true adaptive solution, ATSPMs give agencies the opportunity to make near-real-time adjustments based on data from the field. There has been previous research on the safety impacts of Adaptive Signal Control Technology (ASCT), but the same level of research has not been completed for ATSPMs.
This research would quantify reductions in crash frequency and severity resulting from the deployment of ATSPM signal retiming. It would inform public agencies about the safety benefits and help them make funding decisions related to ATSPM systems.
The objectives of this research are to (1) identify and organize ATSPM signal retiming and/or associated operational improvements with respect to site characteristics (e.g., geometry, volumes, etc.), (2) quantify crash modification factors and/or functions associated with ATSPM signal retiming (for all modes for specific conflict types and severity) at a quality that could facilitate inclusion in the Highway Safety Manual or Crash Modification Factors Clearinghouse, (3) develop guidance for the use of ATSPM signal-retiming-related CMFs, and (4) document case study costs and benefits associated with safety improvements resulting from ATSPM signal retiming (expanding on information in FHWA-HOP-20-003).
Direction from the AASHTO Special Committee on Research & Innovation: The scope of work should focus on traditional systems and implications for safety.
