Simulation Study Found That a 50 Percent Automated Vehicle Penetration Rate Reduced Crash Frequency in Sun Glare Conditioned-Light Traffic by About 60 Percent.
Study Simulated Impaired Visibility on a Highway Near Montreal, Cananda to Evaluate the Impact of Automated Vehicles on Safety and Operations.
Montreal
Evaluating Autonomous Vehicle Safety Countermeasures in Freeways Under Sun Glare.
Summary Information
Under bright sunlight, drivers’ vision may be impaired, leading to changes in driving behavior (e.g., unexpected lane or speed changes) and a potential increase in incidents. This study used traffic simulation to evaluate driving behavior under sun glare conditions and test if automated vehicles (AVs) could be deployed as a countermeasure. The simulation model was applied to a 2.2 km (~1.4 mi) segment of the TransCanada highway (A20) just outside of Montreal, Canada.
METHODOLOGY
A sun glare detection algorithm was developed using location coordinates, time, and weather data, such as cloud coverage (March to May 2018). Sun glare was verified by in-vehicle video data collection in May 2018. The researchers analyzed traffic flow data in different visibility situations to identify a correlation between driving behavior and impaired visibility, then calibrated a traffic simulation model using different traffic flow, AV composition, and AV market penetration parameters. AV composition (“proportional penetration”) included Cautious AVs (drive conservatively), Normal AVs (standard behavior), and All-knowing AVs (AVAs), i.e., AVs with enhanced perceptive and predictive capabilities. AV penetration ranged from 10 percent to 100 percent. Traffic operations and safety were evaluated based on average vehicle delay, frequency of rear-end collisions, and conflict severity in light, moderate, and near-congestion conditions.
FINDINGS
- A 50 precent proportional AV penetration rate reduced crash frequency in sun glare by roughly 58 percent in light traffic, 20 percent in moderate traffic, and 40 percent in near-congestion. Crash frequency decreased by about 25 percent, 18 percent, and 25 percent in the same scenarios in overcast conditions.
- Exclusive penetration of AVAs at 50 percent reduced crash frequency by as much as 78 percent in sun glare conditions and light traffic.
- Proportional penetration of all types AVs improved traffic operations for sun glare scenarios, with a reduction in average delays ranging from roughly 10 percent to just over 40 percent depending on traffic flow conditions and penetration rate.
- Penetration of all AVAs showed the best improvements in operations, with a reduction in average delays ranging from roughly 15 percent to 100 percent.
- Proportional penetration of all types AVs showed an increase in conflict severity, while penetration of all AVAs showed a significant reduction in conflict severity.
