Nudging drivers: The influence of innovative green-phase forewarning systems on drivers' start-up behavior at signalized intersections

Traffic congestion, especially at signalized intersections along urban arterials, poses a global challenge affecting travel efficiency, mental health, and air quality. This study investigates the effectiveness of innovative forewarning systems in reducing start-up lost time at signalized intersections. In this regard, four different forewarning systems were tested and compared with the untreated control condition in a driving simulator experiment inviting 61 participants with a valid driving license. All the tested conditions were tested for two different waiting times, i.e., 20 s and 60 s to evaluate their impact on reaction times, start-up lost time, and early start-up behaviors. The results of the study demonstrated that among the tested conditions, the clock-based VMS with a 2 s (VMS_2s) warning proved to be the most effective in significantly reducing start-up delays by 21.2 %. In addition, VMS_2s and R_yellow; the condition where the yellow signal was displayed simultaneously with the red signal during the last two seconds, effectively reduced drivers' reaction times at the onset of green signal by 53.5 % and 62.4 %, respectively. Moreover, the results did not reveal any instance of risky early start-up behaviors, such as red light running violations. Based on the study findings, the VMS_2s and R_yellow conditions are suggested for further evaluation and potential real-world implementation to improve drivers' start-up behavior at signalized intersections. • Different treatments were compared to to reduce start-up delays at signalized intersections. • Clock-based VMS with 2 s reduces the start-up delays by 21.2 %. • VMS_2s and Red_yellow reduce reaction times by over half. • VMS_2s and Red_yellow signal treatments are recommended to reduce start-up delays.