Study on Influence of Transition Signal Setting on Safety of Nonmotorized Traffic at Intersections

Currently in most Chinese cities, transitional signal setting at intersections has various kinds, the most common being yellow light, flashing green or green signal countdown at the end of green light, and red/yellow light or red signal countdown at the end of red light. The typical mixed traffic, as well as non-motorized vehicles sharing the same signal with motor vehicles, contributes to most incidents and disorder at intersections. All these make it urgent to conduct research in-depth on reasonable transition signal setting, This paper aims to illustrate the influence of transition signal setting to the safety of non-motorized traffic at signalized intersections. Based on the non-motorized vehicle traveling data collected at five typical intersections in Shanghai, a significance comparative analysis of green-red transition signal setting was made using red/yellow-running violation rate as evaluation index. Then further research was developed on comparative analysis of the start-up time of non-motorized vehicles caused by red light, red/yellow light and red signal countdown respectively, the results concluded that non-motorized vehicles enjoy more safety in flashing green than in Green signal countdown. Furthermore red signal countdown usually makes non-motorized vehicles arrive at conflicting points ahead of time at the onset of green light, which would weaken the protective effects of intergreen intervals on vehicles in adjacent phases and has serious potential safety hazard.