Study on the Start-Up Lost Time and Saturation Headway at the Signalized Intersection With and Without Countdown Display

Abstract

Start-up lost time and saturation headway are the key parameters in designing the lane configuration and traffic signal control of signalized intersection. It could depict the behavior of different drivers in different locations and also indicates the traffic management performance of each intersection. By knowing the correct start-up lost time and saturation headway, the signal control can be designed appropriately, which leads to the efficient intersection management. In this paper, based on the field survey data from 3 countdown signalized intersections and 3 non-countdown signalized intersections in Bangkok area, a comparative analysis of the start-up lost time and saturation headway has been made. The analysis showed that the average start-up lost time of each intersection was ranging between 1.99 to 4.50 seconds; the average start-up lost time of the signalized intersections with and without countdown displays were no statically significant different with the value of 3.54 and 3.28 seconds, respectively. The average saturation headway of each intersection varied from 2.36 to 2.75 seconds; the average saturation headways of signalized intersections with and without countdown displays were 2.58 and 2.50 seconds, respectively, with no statically significant different. Furthermore, the hypothesis testing on the data collected during peak and off-peak periods showed that the start-up lost time and saturation headway from both periods were not statically significantly different as well.