A Smart Work Zone Speed Notification (SWZSN) system aims to reduce congestion, queuing, and rear end crashes in work zones by informing drivers of downstream segment speed. The system uses an Intelligent Lane Control System (ILCS) and Portable Changeable Message Signs (PCMS). The SWZSN system was installed at nine stations along a 4.4-mile segment of I-94 in St. Paul, Minnesota in Spring 2016. Video footage was collected from Spring 2016 to Fall 2017 to support the evaluation, using computer vision to extract vehicle trajectory data. A regression analysis used calculated vehicle deceleration rates, detector speed data, and PCMS message logs to examine the effects of various combinations of sign messages and starting speeds on driver deceleration rates.
Overall, the SWZSN system led to mixed traffic safety results. The key finding from the study was that the system is noticed by drivers and resulted in a statistically significant influence on driving behavior.
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