InTrans / Oct 07, 2020
ATSPMs make traffic signal management proactive, not reactive
Traffic signal management is an ongoing struggle for local municipalities. The desire to improve safety and service is often at odds with congestion and costs. That is where ATSPMs, better known as automated traffic signal performance measures, come in.
The Federal Highway Administration (FHWA) recently promoted ATSPMs in their fourth round of Every Day Counts (EDC-4) as a means to improve on traditional retiming processes by providing continuous performance monitoring capability.
But what does that mean? Here is a little background.
According to the FHWA, there are more than 330,000 traffic signals operating in the US, and highway agencies typically retime these signals on a three- to five-year cycle at a cost of approximately $4,500 per intersection.
And how are a large portion of these signals monitored? Citizen complaints, which are only reactive at best, result in added congestion when traffic signals fail and increase public dissatisfaction.
According to Christopher Day, an affiliate researcher with the Center for Transportation Research and Education (CTRE) at InTrans, who has worked with various Iowa cities and counties in adopting ATSPMs, the manual collection of traffic data and continued dependence on software modeling often result in huge losses.
“Short-term data collection methods typically last for no more than 48 hours and can usually only capture traffic volumes and no other operational data. ATSPMs are able to develop a fuller picture of the signal operation over a longer time period,” said Day.
But with ATSPMs, signal retiming efforts now can be based directly on actual performance, which can speed up an agency’s data-logging capability to proactively identify and correct deficiencies.
“Agencies are now able to make a change to the signal timing and confirm its effects using data, rather than a short-term field observation,” added Day. “ATSPMs also make it possible to begin identifying and addressing issues before they become severe enough to generate complaint calls.”
That is because ATSPMs can be applied to a wide range of signalized intersections as well as use existing infrastructure. Recent research, as part of a collaboration between the FHWA, AASHTO, and various state DOTs, have shown that ATSPMs also support the validation of other technologies and operational strategies (such as adaptive signal control and emerging connected vehicle application).
Ultimately, ATSPMs are beneficial because they provide targeted maintenance, improved operations, and increased safety.
“Traffic signal systems have different components working together at various levels to serve a variety of objectives. ATSPMs offer a way to help keep these systems in working order and ensure that they continue to meet those objectives,” said Day.
A Transportation Pooled Fund study, “Traffic Signal Systems Operations and Management,” led by the Indiana DOT with participation from the FHWA, 11 state DOTs, and the City of Chicago, produced a series of reports documenting applications of ATSPMs. The Utah DOT developed an open source software option for a web-based processing and delivery of ATSPMs that provides a framework for continued innovation in data analysis techniques. The collaborative development of ATSPMs has produced a number of implementation options to fit a range of agency capabilities and resources.
For more information related to recent ATSPM case studies, as well as workshops and resources, visit the FHWA website here.