Simulation Research On Traffic Capacity And Safety Of Mixed Toll Station Based On Cellular Automata

The disadvantage of setting up toll stations is that they will reduce the speed and capacity of the tolls.Therefore,improving their traffic capacity and improving traffic safety is an effective way to improve the traffic conditions of expressways.On the one hand,the methods of using traffic flow theory to study the toll capacity of toll stations are mainly queuing theory models,car-following models,etc.,while queuing theory models,car-following models have static and many preconditions.On the other hand,research on traffic safety at toll stations at home and abroad mainly focuses on direct safety evaluation based on accident statistics.The direct safety evaluation method based on accident statistics has shortcomings such as small sample,large area,long period,low reliability,and obviously manifests as incompatibility to small area traffic safety evaluation,especially toll stations.In view of these two considerations,this paper takes the Nanjing toll station of Nanjing-Hangzhou Expressway as the research object,and constructs the cellular automata model to simulate the traffic capacity and traffic safety of the mixed toll station.Firstly,the paper introduces the general situation of Nanjing-Hangzhou Expressway,gives the structure of Nanjing mixed toll station,and then takes video,collects and sorts the data from the mixed toll station,and provides examples and data for the following simulation modeling.First of all,the paper introduces the general situation of Nanjing-Hangzhou Expressway and the structure of Nanjing mixed toll station.Then,the mixed toll station is photographed,collected and sorted to obtain traffic flow data,which provides examples and data for the following simulation modeling.Secondly,the thesis takes the Nanjing toll station of Nanjing-Hangzhou Expressway as a reference example to construct the cellular automata model of the mixed toll station.First initialize the parameters,which are road parameters and vehicle parameters.Then the road is initialized,the actual space is transformed into the cell space,and the cell space matrix is constructed.According to the vehicle model ratio and the lane ratio,the vehicle is placed in the cell space,and then the lane changing rule is determined as follows: the vehicle selects the number of lanes in front of the empty cell,the ETC vehicle and the MTC vehicle to divert,and the truck to the right two lanes.Vehicles of various models are operated at different locations according to surveys and equivalent speeds,and vehicles are updated according to vehicle speed and lane change rules.The traffic flow state of the mixed toll station in three different scenarios is simulated.By comparing the simulation results of the cellular automaton with the actual observations in two-dimensional dynamics,the number of vehicles passing through the toll lanes,the number of queued vehicles,and the total number of lanes changed.The fitting of the four aspects shows that the model can better simulate the actual running state of the mixed toll station traffic flow.Again,the capacity parameter module is designed in the CA model.Then,the influencing factors of the actual toll capacity of the mixed toll station are classified into input variables and terminal variables.The MTC channel opening and closing combination scenarios are divided into three categories(the first scenario: closing the MTC right-most channel;the second scenario: closing the MTC intermediate channel;and the third scenario: closing the MTC left-most channel).Simulation results were obtained according to the orthogonal experimental table.Based on Minitab software,the simulation results were analyzed visually and analyzed by variance.The traffic capacity and departure frequency,vehicle ratio,ETC vehicle ratio,ETC channel number and MTC channel number were obtained under three scenarios.The impact on capacity.Finally,the paper puts forward the necessity of studying traffic safety of mixed toll stations,and analyzes the factors affecting the traffic safety of toll stations.Based on this,the paper proposes the concept of using traffic conflicts to study the mechanism of vehicle conflicts in toll stations.The definition and classification of traffic conflicts and traffic conflict analysis of mixed toll stations,and proposed new traffic safety evaluation parameters of mixed toll stations.Secondly,the cellular automata model is used to simulate the traffic of the mixed toll,and the traffic safety parameter module is constructed.A large number of simulation results are obtained by multiple simulations.Finally,based on the SPSS software,the fitting results of the simulation results are obtained,and the relationship between the total number of lane changes(dependent variable)and the influencing factors of the three independent variables(the starting frequency,the speed of the expressway car,and the gradual rate)are obtained.The results show that there is a positive correlation between the departure frequency and the total number of lane changes.There is a negative correlation between the speed of the expressway car and the gradual change rate and the total number of lane changes.