Wrong-way crashes are a nationwide problem. Despite being relatively rare events, these types of crashes are more likely to be deadly. In Arizona, from 2004 to 2014, 25 percent of all wrong way crashes were fatal. To tackle, this the Arizona Department of Transportation (ADOT) started focusing on the use of technology and other countermeasures to reduce the risk of wrong-way crashes, and designed an integrated, corridor-level system with three main goals that were as follows: a) Detecting and tracking wrong-way vehicles, b) Alerting both wrong-way drivers and other motorists who could be in danger, and c) Notify law enforcement. A 15-mile segment of I-17 in metro Phoenix was selected as the corridor for the wrong-way vehicle detection system pilot project and became operational in January 2018. This corridor had the highest potential for future wrong-way incursions, based on the historical number of wrong-way vehicle crashes along that corridor. The pilot system was designed to utilize existing power and communication systems along I-17. The pilot system used 90 thermal cameras positioned throughout the 15-mile corridor to detect wrong-way vehicles; wrong-way signs with flashing LED lights to alert wrong-way drivers; and dynamic message sign (DMS) advisories to warn right-way drivers.
- Install Thermal Cameras on stand-alone poles. The thermal cameras can register false-positive detections due to wind, pedestrians, truck occlusions, birds and other factors. This can be addressed through improved mounting locations and adjustments to camera’s detection zone and algorithms.
- Post illuminated wrong-way signs with flashing LED borders. These signs made a positive contribution to the wrong-way detection system as a significant number of drivers were able to self-correct due to sign-related countermeasures.
- Use dedicated cameras for inverse detection. This study showed that using the same camera for inverse detection and capturing left turn movements at single point urban interchanges did not work well.
- Provide mainline tracking using thermal and video cameras. Wrong way vehicles can be tracked within and outside a pilot corridor using an existing CCTV camera network that allows traffic operation centers to relay vehicle locations in real time to the Department of safety troopers.
- Integrate DMSs into wrong way detection systems. DMSs should give clear directions to drivers on what actions to take (e.g., exit freeway). It is a cost-efficient element that has the potential to save lives although its absolute impact cannot be easily quantified. Based on the public feedback during the pilot, it is recommended to use message wording “Wrong Way Driver Ahead – Exit Freeway” to give drivers clear direction on what action to take.
- Integrate Decision Support Software for easy communication with law enforcement. This can help with the rapid communication with law enforcement and help send out automated warning messages to the driving public. It also reduced the time between incursion and apprehension of wrong-way vehicles.