Countdown timers, video surveillance and drivers' stop/go behavior: Winter versus summer

This paper presents an analysis of drivers' stopping and traversing behaviors during inter-green periods. Eight intersections were observed in Changchun, China both with and without countdown timers and/or video surveillance during summer and winter. The impacts of the devices on the drivers' behavior were examined and compared between the two seasons from a safety perspective. During winter abrupt braking on icy road can be very dangerous. The analysis was performed by dividing the approach leg into 10 m intervals up to 90 m upstream from the stop line. Three impacts are studied, including the profile of approaching speeds, the stop/go decision, and the maximum acceleration and deceleration. The findings revealed that installing both a countdown timer and CCTV in summer, or either of the devices in winter can increase drivers' stopping tendency and hence reduce red-light violations. Especially on an icy road during winter, a countdown timer can help smooth decelerations, which tend to begin earlier than at the intersections without the device, reducing the incidence of sudden braking.