Abstract: Lanes changing occurrs frequently in freeway interchange diverging area,which leads to the disruption of traffic flow and lots of traffic conflicts.In order to analyze the traffic safety in the diverging area,this study analyzed on the relationship between traffic conflicts and the characteristics of traffic flow such as the headway and vehicle lanes changing zone.The gap acceptance theory was used to judge the traffic conflict interval and to build a traffic conflict predicting model of interchange diverging area.The results show that there is a significant and positive correlation between the lanes changing zone and the traffic conflict point,both of which are located within 600 m from the reference point and the first 60 m of the deceleration lane,that the critical headway of traffic conflict is 2.21 s and the traffic conflict headway interval based on gap acceptance theory is (2.06 s,2.31 s),that the relative error between the result predicted by using the model and the actual statistical results is below 10%,and that the length of deceleration lane and diversion ratio are the main factors affecting the number of traffic conflicts and can provide a sound basis for improving traffic safety in diverging area.

Key words: freeway interchange, diverging area, traffic conflict predicting model, vehicle lanes changing zone, gap acceptance theory