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 10m intervals up to 90m 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.