Study Of Rear-end Crash Risk At Signalized Intersections Based On Cellular Automaton Model

ABSTRACT:Traffic safety of urban road intersections was always the focus of traffic management department and traffic researchers. Road intersections are the basic junctions of city road network which are also the bottlenecks to the road capacity and traffic safety. Therefore, the accidents occurred near the intersection usually bring worse influence to the traffic than which occur at the road segment.Amber dilemma zone is one of the main risk situations to signalized intersections. It is really hard for approaching cars in the dilemma zone to make a stop/go decision for the reason that they not onlycan hardly go through the intersecion during the amber signal but also cannot slow to stop before the stop line, thus will increase the occurrencesof several risk situations like slamming on the brakes, red light running and rear-end crashes. Traffic engineers design a lot amber decision aids devices to most reduce the effects of amber dilemma, for example countdown signal device, flash green device, signal ahead pavement and so on. However, it seems these devices or rules donot make much means. To deter traffic crashes at the intersection, a new traffic rule that drivers must not go through the signalized intersections during the amber light was issued in China. No sooner had the amber light ban been announced than it got widespread social concerns and debates for its potentialsafetyhazards before the intersection.This paper tries to evaluate the effect of the newly announced stop-amber-light rule by the comparison of go-amber-light rule and "siganl ahead" pavement rule from the respective of traffic capacity, rear-end risk situations and brake withthe method of micro-simulation.The simulation was conducted within the farmework of CA model. Field data collected from Beijng and Florida are applied to analyse the drive behaviors during the amber signal at the intersection and calibrate the relevant parameters of the CA models.Simulation results show that the stop-amber-light rule will not only reduce the traffic capacity of the intersection but also increase the occurrences of rear-end risk situations before the intersection.At last a pre-signal amber light control strategy was proposed and then validated based on the comparison of other amber light control strategies. These results may make some significant instruction for amber signal desin and signal control scheme of intersecion.