Impact of Green Signal Countdown Devices on Driving Behavior using Cellular Automaton Model

Green Signal Countdown Devices (GSCD) have been becoming increasingly common at urban intersections in China during recent years. However, controversy about the impact of GSCD on driving behavior still exists. To better understand the impact of GSCD on driving behavior at the last several seconds of green phase and amber phase, a one-dimension Cellular Automaton (CA) model based on NaSch rule is formulated. Approaching speed and car spacing are applied as two indicators for driving behaviors. The simulation results show that in peak hours, the approaching speed is larger at intersection with GSCD, especially in the segment close to stop line. Whereas, it is much lower in off peak hours compared with intersection without GSCD. Additionally, with the presence of GSCD, larger car spacing is observed during off-peak hours. However, the effect of GSCD on car spacing in peak hours is not significant.