Impact of Driver and Surrounding Traffic on Vehicle Deceleration Behavior at Onset of Yellow Indication

This paper discusses driver deceleration levels in a controlled field environment at the onset of a yellow indication on high-speed signalized intersection approaches using an in-vehicle differential Global Positioning System. The impacts of driver gender, driver age, roadway grade, mean approach speed, platooning scenarios (leading, following, or alone), and time to intersection (TTI) on driver deceleration levels were analyzed. This information is critical for the efficient and safe design of traffic signal clearance timings. The IntelliDrive initiative can gather information about the driver, subject vehicle, and surrounding traffic conditions to execute safe and customizable traffic signal indication change warnings. The results indicate that driver deceleration levels are significantly higher than the 3-m/s² deceleration level used in the state-of-the-practice traffic signal design guidelines. The mean deceleration level is 3.6 to 4.1 m/s². The results can be used to enhance the design of yellow timings and may be integrated with the new IntelliDrive initiative to provide customizable driver warnings. The results demonstrate that driver deceleration levels are higher at shorter TTIs at the onset of yellow. Drivers are willing to exert deceleration levels in excess of 7 m/s² at short TTIs (less than 2.5 s). Furthermore, older drivers (60 years of age or older) employ greater deceleration levels compared with younger (under 40 years old) and middle-aged (between 40 and 59 years old) drivers. A driver following another vehicle that proceeds legally through an intersection without stopping exerts higher deceleration levels than drivers driving alone on a roadway or leading another vehicle, and drivers leading a platoon of vehicles are not affected by vehicles behind them.