Modeling And Simulation Of The Influence Of Taxi On Urban Road Traffic Flow

With the continuous expansion of urban scale and the increasing traffic demand,traffic congestion and vehicle delay in urban roads have been particularly prominent.As an important part of urban traffic,taxis generally have unconventional operation behavior such as "forced change,urgent stop,stop and down passengers at random" and so on driven by its profitable operation mode,which has caused great interference to the normal traffic operation.In view of the problem of taxi random stopping,the management department has set up taxi stop,but the effect is not satisfactory.Therefore,how to organize the taxi stopping is one of the most urgent problems to be solved in urban traffic.In addition,when the taxi stop and the bus stop both exist,the influence of the different combination configuration on the traffic flow is still need to be studied.With the help of the theory of cellular automata and taking full consideration of the characteristics of urban road traffic flow,the traffic flow models of two-lane considering the characteristics of taxi operation and different stopping behavior are established respectively,The evolution of traffic flow under different parameters is studied.In addition,the influence of bus stop is added,and the influence of different combinations of stops on traffic flow is also discussed.The main points are summarized as following:(1)Starting with the driving behavior of taxis driver,the differences between taxis and other vehicles is analyzed from the car following distance,lane changing frequency and the choice of lanes,then the speed and lane change rules of the vehicle in the city road are re-calibrated,Then a traffic flow cellular automaton model of urban two-lane considering taxi operation is constructed.The influence of different taxi proportions on traffic flow is explored from the aspects of traffic flow,average speed,lane change rate and road occupancy.(2)The traffic flow models under the curbside stop and the harbor shaped stop of taxis are established,the traffic flow characteristics under the mixing proportion of the vehicles,the different entering probability,stop time and the berth of the stop are compared and analyzed.The bottleneck effect caused by the stop is studied,and the change characteristics of the average velocity in the upstream and downstream of the stop is revealed.The results show that the interference of the harbor shaped stop on the traffic flow is less,and the characteristic is more obvious in the saturation phase;the stop time has a greater impact on the curbside stop,and the increase of the number of berth of the stop is mor e significant to the harbor shaped stop.(3)A taxi random stopping model is constructed considering the random stopping behavior of taxis.The road traffic capacity and safety characteristics at random stop and definitive stop are compared from the aspects of traffic flow,average speed,change rate and velocity difference.The results show that the random stopping behavior has a greater impact on road capacity.With the increase of taxi proportion,the traffic flow and average speed under random stopping behavior are greatly reduced especially in the right lane;the average forced lane change rate and the standard deviation of the speed under the stopping behavior are higher,so the lower road safety performance under the stopping behavior is reflected.(4)Considering the bus stop characteristics,the model based on the combination of the taxi stop and the bus stop is set up.According to the situation of the taxi stop set up at bus stop,the change characteristics of the road space-time diagram,the traffic flow and the average velocity under the different traffic parameters and stop spacing are analyzed,then the influence on the traffic flow is further studied.The results show that when the bus stop is set up in the upstream reaches of the taxi stop,the traffic flow is less affected and the traffic flow and average speed are relatively high.Compared with the free flow phase,increasing the distance between the bus stop and taxi stop has a greater impact on the traffic flow under the saturation phase.