Study On The Traffic Conflict In The Closed Construction Area Of Highway Reconstruction And Expansion

With the slowing down of the new expressway,the reconstruction and expansion of the existing expressway are speeding up,and the research on traffic safety of the reconstruction and expansion of the expressway has become a hotspot.Therefore,the paper studies the traffic conflict in the reconstruction and expansion construction area.At the present stage,the construction methods of expressway reconstruction and expansion mostly adopt the semi-closed form which has relatively little influence on traffic flow and is easy to manage.However,this form has some safety risks because the traffic flow needs to be converted from one half of the road to the other.Therefore,it is of great significance to establish a bayesian network model for the reconstruction and expansion of the semi-closed construction area to study the specific traffic conflict situation,so as to improve the traffic safety in the reconstruction and expansion construction area.According to the two types of sections(half two-way construction section and lane extension section)in the half-closed construction area of expressway reconstruction and extension,six typical sections of jiqing expressway reconstruction and extension construction are observed by tracking radar.Based on the field observation data,the road characteristics,traffic flow characteristics and vehicle driving characteristics of the two sections were analyzed,and it was found that the road environment in the semiclosed construction area was complex and the vehicle headway was low,which was prone to traffic conflicts.Considering the lack of accident data in the newly built construction area and the significant correlation between serious traffic conflicts and traffic accidents,traffic conflicts are taken as the research focus of traffic safety in the construction area.Based on the road characteristics,traffic flow characteristics and vehicle driving characteristics of the two sections,it is found that most of the vehicles in the half-width two-way traffic section are rear-end collisions.TTC(Time to Collision)is selected to identify the traffic collisions in this section.The lane conversion service section of the road is composed of a straight section and a curved section,with both rear-end Collision and lateral Collision between vehicles.TTC and TDTC(Time Difference to Collision)are selected to identify the traffic Collision in this section.Then,according to the correlation between serious traffic conflict rate and accident rate,the threshold of serious traffic conflict is determined to be 4s.Finally,based on the measured data of the reconstruction and expansion project of jinan-Qingdao expressway,the paper analyzes the influencing factors of serious conflicts from three aspects: road,traffic flow and single vehicle.According to the mutual information between the influencing factors and the target variables,the indicators of serious traffic conflict factors were determined,and Bayesialab software was used to establish the bayesian network model of two types of traffic conflict segments.Based on the bayesian network model,the traffic conflicts in these two sections are studied,and it is found that the road factors have a great influence on the traffic conflicts of the two road types.When there is construction on the side of half two-way section,the probability of serious traffic conflict is 32.52%.The probability of a serious traffic conflict in the absence of one is 12.16 percent.When the radius of the circle curve of the lane rotation section is 2630 m,2160m and 1680 m,the probability of serious traffic conflict is 19.95%,34.88% and 54.79%.In addition,vehicle type,average speed and standard deviation of traffic flow speed all affect the traffic conflicts in the two sections.In order to further reduce the probability of traffic conflict and reduce the risk of collision,the vehicle collision risks of the two road types were evaluated based on bayesian network.Meanwhile,measures were proposed to improve the traffic safety in the construction area of the reconstruction and expansion expressway by means of large vehicles diversion,speed limit in sections,and circle curve radius of lane rotation section.