Improved Traffic Flow Efficiency During Yellow Interval at Signalized Intersections Using a Smart Countdown System

Inadequate and unnecessary stopping at signalized intersections reduces operational efficiency. The study aims at investigating the effect of a smart advanced warning system on driving behavior and the efficiency of signalized intersections. A green LED dynamic light (G-LED) system (combined system with countdown strategy) is developed and evaluated by means of a driving simulator experiment. The efficiency of the proposed system is compared with a default traffic signal condition with green-yellow-red order (i.e. control condition), and a flashing green (F-green) traffic signal (i.e. order: green-flashing green-yellow-red). Sixty-seven participants holding a valid driving license from Qatar participated in the study. All the participants drove a simulation run replicating the real-world environment of the Corniche road in Doha city (Qatar). Data such as vehicle lateral or longitudinal position, travel speed, acceleration or deceleration, and violation tickets were collected for each participant using the STISIM Drive®Software. Results from a binary logistic regression model showed that the probability of crossing during the change interval significantly increased for the G-LED condition compared to the control condition, while it decreased in the F-green condition. Furthermore, the experiment disclosed that the odds of crossing the intersection (without red-light running) for the proposed smart advanced warning system (G-LED) were 29.67 and 2.58 compared to the F-green and the control conditions, respectively. Furthermore, the time-space and speed analyses revealed that most of the drivers decelerated in the option zone and decided to stop at the intersection equipped with flashing green signal.