Research on traffic characteristics and traffic conflicts of one-way closed work zone on expressway

In order to analyze the traffic characteristics and traffic conflicts of one-way closed work zone on dual-way-four-lane expressway, statistical analysis was applied based on traffic investigation and conflict survey. Firstly, the queuing traits of vehicles on the upstream buffer area of the work zone were analyzed, and the Erlang distribution model which can describe the distribution of headway was calibrated. Secondly, speed distribution characteristics of all the subsections of the work zone were determined, and the speed limit scale of each subsection was proposed. Then, the types of traffic conflicts were summarized, and the determination of rear-end conflict severity degree based on time-to-collision (TTC), as well as the prediction model of rear-end conflicts based on Negative Binomial distribution, were put forward. Lastly, traffic simulations based on VISSIM were conducted. The results show that the rational length of the upstream buffer area should be between 45-70 m based on the queuing traits, the speed limits of the work zone should be determined according to the traffic volume on it; and when the level of traffic volume is unchanged and the speed limit is higher than 50 km·h^-1, the number of traffic conflicts will increase dramatically with the increase of the speed limit.