Evaluating Driver Speeding at Traffic Signal Lights During the Amber Time: With and Without Countdown Timers

Abstract

At the onset of amber color indication, drivers must decide whether to stop or cross a signalized intersection. In literature, there is enough evidence indicating that a significantly high number of crashes that occur at signalized intersections are of vehicles entering the intersection during amber and red-light indications. However, such findings cannot be stated for Sri Lanka with the lack of details in the crash records. With that gap of knowledge in the local literature, this study investigated how countdown timers (CDTs) impact on the speeding behavior of drivers. With that aim, the objective of this study was to examine driver speeding according to the distance to stop line (DSL) with the presence an absence of countdown timers (CDT). Two intersections with CDTs and one without a CDT in Colombo, Sri Lanka were considered for data collection. The number of vehicles that are speeding at the onset amber, were considered during a peak hour. These values were obtained for the intersections with and without CDTs as well as for Peak and Off-peak conditions. It was found that the dilemma zone was within 15m to 30m from stop line for intersections with CDTs. Results showed that the presence of a CDT showed no significant impact on the number of vehicles that went speeding at the onset of amber, and it was around 22 veh/ 100 cycles. On the other hand, there was a 35% reduction in the number of speeding vehicles per signal cycle during the off-peak hour with the absence of a CDT