Intersection collision‑avoidance pilot draws interest for preventing T‑bone crashes
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Summary
Consultants and district staff described ICAST — sensors and software that predict red‑signal violations and briefly extend an all‑red phase. The TPO board heard pilot results, learned the project expanded to 25 intersections with a $500,000 grant, and asked staff to include further study in future UPWP work.
Traffic engineers and TPO members spent the meeting’s middle session examining an intersection collision‑avoidance pilot that uses sensors and connected data to predict vehicles likely to violate red signals and briefly extend the all‑red phase.
Consultant Angelo Rao (Kittelson and Associates) described the predict‑verify‑extend‑resume approach and said early testing and laboratory review (TURL) validated the technique. The pilot began at four intersections and, after a state grant, expanded to 25; Rao said the project was awarded roughly $500,000 to scale the work and that latency and communications have improved since early trials.
How it works: sensors and connected‑vehicle or mobile data identify a vehicle unlikely to clear the intersection on green, the system performs a verification calculation and, when warranted, extends the all‑red clearance for a few seconds so cross‑traffic does not receive a conflicting green. "The all‑red phase is extended about 2 to 4 seconds — in this case, three seconds," Rao said.
Board members praised potential reductions in high‑severity, angle collisions but raised concerns about secondary effects, notably rear‑end crashes and liability if the system generates false positives. Dr. Wong and district staff said the technology is low cost compared with full signal replacements — district analysis indicated sensors add roughly $5,000 per intersection on top of typical local hardware costs — and emphasized the need for rigorous before/after crash and near‑miss analysis before wider deployment.
District officials said TURL (a traffic engineering research lab) conducted field analysis and supported the approach; Rao said tests included deliberately run red lights under controlled conditions to validate sensor detection and messaging to other devices. Board members and staff agreed the post‑pilot crash and near‑miss data will determine whether to pursue broader implementation; staff suggested the technology could be considered for inclusion in future UPWP planning studies.
What’s next: the district and TPO staff will deliver post‑implementation analyses (crash and near‑miss data) for board review; members asked staff to return with raw numbers and cost data to support a potential countywide rollout.