Safety Diagnosis Of Urban Intersection Based On Traffic Conflict Technology

The grade-intersection is the very important junction of the transportation network, where most of traffic accidents happened. Improving the safety level of intersection will have much to do on decreasing traffic accidents. It is an effective way to improve the safety level of the intersection by diagnosing it based on the present traffic condition and proposing the specific improvement countermeasures according to the factors which may lead to accidents.The index used to judge the severity degree of conflict is selected first and then how and when observe the conflict is discussed. Conflicts between automobiles, automobiles and bicycles, automobiles and pedestrians are summarized and analyzed in the paper. It is demonstrated that the frequency of serious conflict are from Poisson distribution when the number of samples is very large. It is also discussed how to calculate the critical value using to estimate whether the unsafe factors brought by certain type of serious conflict increase. The safe degree of Sidaokou intersection is assessed applying the theory above. Aiming at reasons resulting in conflicts at urban intersections, measures of reducing conflicts occurring between automobiles, automobiles and bicycles, automobiles and pedestrians are presented from the aspects of technology and management. Approaches of treating and rebuilding intersections on which accidents happen frequently are also presented. It is introduced that how to decide the order of improvement measures according to Benefits/Costs. Finally, the reasons why Sidaokou intersection becomes more unsafe are analyzed and the relevant improvement measures are put forward.