Study of Truck Driver Behavior for Design of Traffic Signal Yellow and Clearance Timings

Abstract

Traffic signal violations by drivers are a leading contributor to crashes at signalized intersections. The yellow indication is used to inform drivers of an upcoming change in the status of the traffic signal. Yellow interval durations are currently calculated to provide dilemma zone protection for passenger cars. Because of differences in vehicle characteristics and driver characteristics, heavy trucks such as tractor trailers behave differently at the onset of a yellow indication. This paper characterizes the difference in driver behavior between truck and light-duty vehicles at the onset of the yellow indication and then revises the yellow timing procedures to address the truck requirements. A data set of 910 stop–go records was collected through the use of a truck driving simulator located at the Virginia Tech Transportation Institute. From the data collected, statistical models were created to model driver perception–reaction times and deceleration levels with a consideration of driver attributes and the time to the intersection at the onset of the yellow indication. The data collected, along with the statistical models developed, were compared with the data collected and the statistical models created by the same research organization in a study of passenger car drivers. Last, a Monte Carlo simulation was conducted to develop appropriate yellow indication timings to provide adequate dilemma zone protection for trucks.