Mitigation of Wrong-Way Driving Events Captured by Vision-based Site Monitoring Systems in California Led to Safety Benefits.
Wrong –Way Driving (WWD) can cause accidents that may unfortunately result in fatal injuries. Given the severity of the situation, especially near busy freeway ramps, this study evaluated a solar-powered, Vision-Based Site Monitoring (VBSM) system, utilizing an integrated camera, solar power panels, and a modem for communication. The goal of the VBSM system is to capture and mitigate WWD events at ten exit ramps in Northern California in Sacramento, and two exit ramps in Southern California in San Diego. This study involved data collection that lasted 39 months from June 5, 2016, to August 31, 2019. The San Diego exit ramps were installed with the VBSM systems in December 2017 with a monitoring duration of approximately 20 months. This study also evaluated the performance of several mitigation techniques implemented by California DOT (Caltrans) to minimize or eliminate WWD incidents, by monitoring the mitigated sites before and after mitigation. The two San Diego exit ramps were mitigated on January 23, 2018. Six Sacramento exit ramps were mitigated on November 9, 2016, while four were not mitigated during the period of this study for control purposes.
The VBSM system utilizes an integrated, outdoor-ready network camera, with a built-in processor to support on-board analytics for WWD detection and traffic volume counter, along with numerous protocols and security features. In addition, the VBSM system contains a commercial off-the-shelf analytics software package, which runs directly on the camera's CPU, and includes multiple modules: The wrong-way vehicle module allows the user to configure the VBSM system for multiple detection zones. There is also the traffic count module. For communications, the VBSM system includes Long-Term Evolution (LTE) cellular for configuring, monitoring, and resetting cameras as well as updating software and firmware. The VBSM systems are also equipped with a modem to provide an LTE communication link. The modem is also responsible for measuring battery voltage and transmitting data, including battery voltage and device temperature, to the research team’s server. This allows for ongoing system health surveillance and remote troubleshooting. In the period evaluated for this study, the VBSM systems captured 34 significant WWD events, 29 of which were events where drivers turned around (driver-corrected). WWD mitigation strategies implemented by Caltrans included additional signage, direction-specific turn signals, and active monitoring and alerting flashing LED light systems operated by private traffic control companies.
The annual rate of wrong-way incidents per exit ramp in Sacramento significantly decreased from 3.0 to 1.4 after the implementation of mitigations. This denotes a 53 percent reduction in the frequency of such events on the mitigated exit ramps.