Research On Mechanism Of Traffic Conflicts At Malformed Intersections In Mountainous City

Due to the limitations of terrain,landform and climate,a large number of malformed intersections exist in mountainous cities.Because of the special road alignment,the traffic operation characteristics of these malformed intersections are different from those standard intersections in plain cities.According to the investigation and research,more serious traffic conflicts happened at malformed intersections than at standard intersections,which greatly affect the normal thoroughfare for vehicles and increase the potential traffic safety hazards.Therefore,analyzing the causes and mechanism of traffic conflicts at malformed intersections in mountainous cities has greatly practical significance for improving the safety of urban traffic in mountainous areas.In this paper,firstly,the basic concepts,urban layout and traffic characteristics of mountain cities have been briefly described,and the characteristics of malformed intersections in mountain cities have been detailedly analyzed based upon the perspective of geometric and traffic characteristics.Secondly,referred to the existing theoretical results of traffic conflicts,TTC(Time To Collide)has been chosen as a quantitative index,the severity thresholds about four main types of traffic conflicts have been classified,the straight-left conflict has been determined as the most frequent and serious type of conflict among all traffic conflicts,and the temporal and spatial distribution characteristics of such conflicts at various malformed intersections have been carefully studied.Thirdly,based on the perspective of "pedestrian-vehicle road",nine factors,including traffic volume,intersection type and signal control,have been selected to analyze the direct-left traffic conflict at malformed intersections in mountainous cities,and a traffic conflict prediction model on account of generalized linear basic theory has been given.Fourthly,based on the simulation experiments,the model prediction results,the relative traffic factors,distribution and regularity of serious traffic conflicts at various types of malformed intersections in 127 different traffic environments,the mechanism of traffic conflicts at malformed intersections in mountainous cities has been revealed.Finally,real cases have been chosen at Renmin Road-North District Road intersection and Wujian Road intersection in Chongqing main urban area.The analysis results showed that the analysis results of traffic conflict mechanism and the prediction model are reasonable and reliable.In this paper,a traffic conflict prediction model for different types of malformed intersections was constructed by combining actual observation with traffic simulation experiments,and the mechanism of traffic conflict at malformed intersections in mountainous cities was given.The research results lay a foundation for perfecting the existing traffic safety analysis and evaluation methods of malformed intersections.