Driver Response to an Actuated Advance Warning System

Abstract

This paper analyzes driver behavior when alerted to the impending end of green while they travel on high-speed signalized intersection approaches that are equipped with actuated advance warning (AAW) systems. These systems are widely deployed in Nebraska and provide a more than 90% likelihood of improving safety. They consist of one detector placed in advance of the intersection and active warning signs with the legend, “prepare to stop when flashing.” The overall goal is to reduce, if not eliminate, the number of drivers who are caught in the dilemma zone. A nonintrusive mobile data collection system was used to monitor traffic and collect a continuous stream of traffic data up to 304.8 m (1,000 ft) upstream of the stop line on two high-speed signalized intersection approaches that were equipped with AAW systems. The results indicate that the system is effective at alerting drivers to the impending end of the green light; approximately 78% of the drivers observed in this study either maintained their speeds or slowed down when the active warning signs began to flash. The number of vehicles in their dilemma zones was statistically significantly lower than would be expected if the AAW system was not used.