Effect Of Countdown Timer On Traffic Operation At Signalized Intersection

Countdown has been applied to signalized intersections in many cities in China, countdown attached next to the signal lamp, with the number displayed next phase switching of the remaining time, it's warn the driver of the next phase of the start time. There are less research on intersections efficiency in our country about countdown.This paper targets at typical intersections in Changsha City, from the efficiency and safety angles to study the impact of countdown. In the matter of operating efficiency, selected the headway distribution, saturation headway and start delays and other parameters during green light. Based on video data, t-test method in SPSS software has been applied to acquire operating parameters, based on univariate analysis of variance, do significance analysis on impact of countdown (testing the level of p <0.05), verify the validity of the countdown. In the matter of security, selected the red light running rate as the study parameters, based on video data, statistic red - running violations, based on univariate analysis of variance, do significance analysis on impact of countdown, verify the impact of countdown on the proportion of red - running violations.The results of variance analysis showed that: on mixed flow and large - small car following circumstances, countdown to the saturation headway have a significant effect; and on small - large and small– small car following circumstances, there are no significant difference on saturation headway under the condition on with and without countdown. Startup delay shows significant difference on mixed flow and small - small car following circumstances, under the condition of with and without countdown, the countdown to the startup delay was significant. When amber signal start, vehicle speed shows no significant difference, the countdown to the vehicle speed was no significant.