Research On Rear-end Conflict Model Construction And Safety Improvement In Freeway Work Zone

In recent years,China's highway has entered the stage of reconstruction,expansion,maintenance and new construction.It is urgent to improve the safety problems of the freeway work zone area,as the large number of maintenance operations make the freeway work zone area have higher crashes risks than the normal road section.Traffic conflict technology(TCT)is an effective surrogate safety analysis technology which can make up for the difficulty in obtaining historical accidents samples.Therefore,this paper studies the rear-end conflict model and safety improvement measures in the freeway work zone.It mainly includes the following work:(1)Based on the review of freeway work zone safety and traffic conflict technology,this research analyzes the formation mechanism and types of traffic conflicts of freeway work zone,and defines the research object as the rear-end conflict in the freeway work zone.The traffic parameters of the work zone of Zhoulu freeway and Luwu freeway in Anhui Province are obtained through the combination of manual observation and video collection.The traffic characteristics of the work zone are summarized through the descriptive analysis of the collected data,which provides data basis support for the construction of rear-end conflict models.(2)In view of the limitations of the existing conflict discrimination model and the interference of speed limit signs on vehicles this research proposes an improved conflict discrimination index time to collision in work zone(WTTC)based on the time to collision(TTC)model.Using Newton dynamics to establish a conflict discrimination algorithm model based on WTTC,and using the cumulative frequency method to classify the severity of the rear-end conflict,the results show that the model can effectively identify the potential rear-end conflicts in the work zone.(3)Based on the field survey data,the traffic conflict simulation model is established,the parameters that affect the rear-end conflict are analyzed and screened by methods of single factor analysis,orthogonal test,Pearson correlation analysis and so on.Akaike information criterion(AIC)and Bayesian information criterion(BIC)are selected to evaluate the fitting results of the prediction model,and the negative binomial distribution model is used to build the rear-end conflict prediction model in the work zone area.(4)Considering the influence of speed limit value and speed limit compliance rate on the safety of work zone area,the safety improvement measures of adopting hierarchical speed limit scheme are proposed taking the rear-end conflict rate,average speed and speed standard deviation as the optimization goals,from the perspective of optimizing the layout of speed limit signs.The results show that the accuracy of conflict discrimination model and conflict prediction model based on WTTC are improved.The hierarchical speed limit scheme can improve the effectiveness of management and control of road speed and reduce the conflict rate,and effectively improve the safety of the operation area.