2015 Volume 3 Issue 1 Pages 282-294
A countdown timer can reduce startup delays and improve queue discharge; however, many researchers have reported an increased occurrence of red light violations with the use of such timers. We conducted an experiment to examine whether it is possible to retain the benefits of the countdown timer while limiting the problem of red light violations at startup when the signal switched from red to green. This experiment investigated the impacts of different settings of the countdown timer (10 different patterns for timer display) and without the timer on drivers (mainly young male drivers) and on two types of vehicles (with and without the idling stop system). We determined their influences on the startup delay and the proportion of red light violations at startup. Based on the findings, the extent of the reduction in startup delay is more apparent for vehicles with the idling stop system. In the presence of the countdown timer, drivers with the idling stop system responded 65% quicker than in the absence of the timer. The pattern that had the best overall performance in reducing startup delay without increasing drivers' tendency to violate red lights at startup, was to count down by seconds, then to stop the timer and keep the number unchanged for a short period (approximately 3 seconds) before the green phase. These findings may benefit the implementation or modification of countdown-signalized intersections to improve the safety of crossing pedestrians as well as driver satisfaction.