ADVANCING SAFETY PERFORMANCE MONITORING AT SIGNALIZED INTERSECTIONS USING CONNECTED VEHICLE TECHNOLOGY

摘要

Crash-based safety evaluation is often hampered by randomness, lack of timeliness, and rarity of crash occurrences. This is particularly the case for technology-driven safety improvement projects that are frequently updated or replaced by newer ones before it is possible to gather adequate crash data for a reliable and defensible before-after evaluation. Surrogate safety data are commonly used as an alternative to crash data; however, its current practice is still resource intensive and prone to human errors. The advent of connected vehicle technology allows vehicles to communicate with each other as well as infrastructure wirelessly. Through this platform, vehicle movements and signal status at the facilities can be automatically and continually monitored in real time. This study explores the viability of long-term monitoring of connected vehicle data for safety performance evaluation. This paper proposes a safety monitoring application that utilizes connected vehicle data to detect potential safety indicators at signalized intersections. As limited saturation of on-board equipment (OBEs) is expected in the near-term evolution, the development focuses on a roadside equipment (RSE) application that can process data elements from OBEs via vehicle-to-infrastructure (V2I) communications using standard message sets. A microscopic simulation was designed to evaluate the effectiveness of the proposed safety indicators in detecting degrading safety performance. A signalized intersection test bed was created in VISSIM while the wireless communications capability and the application were implemented using Car2X API. The evaluation results indicated that the application can effectively detect changes in safety performance at full market penetration. Future research is needed to quantify the combination of penetration rates and monitoring periods that can yield effective detection of changes in safety performance at intersections with varying operating characteristics.