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The crash reduction potential of automatic emergency braking systems that respond to bicyclists
David G Kidd1, Luke E Riexinger1, Blaine Ricketts2
1Insurance Institute for Highway Safety, Ruckersville, Virginia.
Objective:
In 2022, 1,105 bicyclists were killed and 46,195 were injured in motor vehicle crashes in the U.S. Automatic emergency braking (AEB) systems that automatically apply the vehicle brakes can avoid or mitigate bicyclist crashes, but the feature is not evaluated or required in the U.S. This study characterized police-reported vehicle-to-bicycle crashes and assessed speed reductions by two AEB systems in controlled tests replicating common crash vehicle-bicycle scenarios.
Methods:
From 2018 to 2022, a total of 159,474 police-reported and 3,305 fatal crashes involving one passenger vehicle and one bicyclist were extracted from the Crash Report Sampling System and Fatality Analysis Reporting System. Crash configuration and pre-impact movement were coded using the Crash Type variable descriptions. Estimated speeds from 93 crashes were extracted from the Vulnerable Road User Injury Prevention Alliance (VIPA) database. AEB system performance in the 2023 Toyota RAV4 and 2023 Subaru Forester was evaluated when approaching a 15 km/h crossing bicycle target at 40, 50, and 60 km/h during the day and when approaching a slower-moving bicycle target ahead at 50, 60, and 70 km/h during the day and night.
Results:
Crossing path crashes accounted for 56% of police-reported vehicle-to-bicycle crashes. The estimated travel speed in VIPA crossing path crashes was most frequently 0-20 km/h for the vehicle and 0-17 km/h for the bicycle. Parallel path crashes accounted for 57% of fatal vehicle-to-bicycle crashes. The estimated speed in VIPA parallel path crashes most frequently was 65 km/h or higher for the vehicle and 0-17 km/h for the bicycle. In controlled evaluations, the AEB systems completely or nearly avoided the bicycle target in the crossing path scenarios during daytime and in parallel path scenarios during daytime and at night with high beams. However, the AEB systems only marginally reduced vehicle speed in the parallel path scenarios at night with low beams.
Conclusions:
Current AEB systems mitigated crossing and parallel path bicycle crashes during the day but not when approaching a bicycle from behind at night with low beams. AEB systems that perform well in every crossing path and parallel path scenario could address 28,600 police-reported and 600 fatal bicycle crashes each year.
