Research On Forecast And Evaluation Of Traffic Congestion Situation In Urban Trunk Road Under Accident Conditions

With the continuous progress of China's urbanization process,the number of vehicles is still in a rising trend,and urban traffic is facing severe pressure.At the same time,the frequent traffic accidents in urban roads lead to the traffic congestion,reduce the road network operating efficiency,and cause the social and economic losses.Facing the traffic accident on the complex road network of the city,crowded evacuation,weaken the impact of road network,to maintain smooth and orderly operation of road network traffic has become an urgent need to solve the problem of urban transport.To solve this problem,it is necessary to have a clear understanding and evaluation of traffic congestion situation,the extent and severity of the congestion caused by the accident.Based on the existing research results at home and abroad,this paper studies the occurrence and spread of road congestion under the condition of accident,analyzes the influencing factors and the mechanism of the congestion situation.Aiming at the urban trunk road,this paper studies the method of forecasting the space influence range of the occasional congestion in the road network,and evaluates the severity of the traffic congestion situation according to the corresponding traffic condition.Firstly,the paper analyzes the types of road traffic congestion,congestion characteristics and crowding metric,and studies the influencing factors of urban road congestion situation,including accident scenarios,real-time traffic environment,road grade,accident location,road network and subjective driving behavior,etc.The paper analyzes the impact mechanism of each factor,determines the criteria for determining of the intensity of non-recurrent congestion,and set the basic situation of the paper.Secondly,based on the traffic wave theory and Van Aerde model to build the prediction model of congestion spread speed,and according to the trunk road traffic function and traffic flow characteristics,the paper considers the influence of accident occupancy lane,the vehicle lane crossing and signal crossing on the traffic flow,and gives the model solving process and method.Further,the paper analyzes the spread mechanism of congestion caused by accident at the network intersection.Based on the prediction model of congestion spread speed,the paper predicts the spatial length range of the crowded trunk road and designs a case and verifies it by VISSIM 4.3 software platform,at the same time,extracts the parameters of software simulation,and analyzes the traffic state characteristics.Based on the spread of the crowded trunk road,this paper sets out the order and rules of the road acceptance decision on the road around the main road,chooses the crowding judgment index and determines the index threshold,and combines the acquisition of the road traffic parameters and the calculation of the index value,predicts the space influence range of traffic congestion on regional road networks.Finally,the paper designs the evaluation process of the road traffic congestion situation under the condition of the accident,establishes the crowding situation evaluation index system which includes the developmental index and the consequential index.The paper takes into account the impact of the accident itself,the surrounding environmental conditions and the speed and extent on the crowded situation,so as to so as to comprehensive evaluation of the severity of the road traffic congestion situation and to determine the level of congestion situation.