Study On Effect Of Mixed Motor Vehicle Traffic Flow On Bus Travel Time Reliability

The tavel time reliability of conventional public transport is not only one of the most important performance indicators for evaluating the operation status of urban public transport,but also an important factor for passengers when choosing the mode of travel.The urban bus operation environment is complex,the traffic flow composed of different types of vehicles and different proportion of buses is complex,which leads to the uncertainty of bus travel time and poor punctuality.Therefore,it is necessary to explore the reliability of bus travel time under the influence of mixed motor vehicle traffic flow,so as to provide theoretical basis for bus operation management and passenger travel.Firstly,this paper expounds the connotation of mixed motor vehicle traffic flow.The data of mixed motor vehicle traffic flow in different road sections are mined.The result shows that the proportion of large vehicles,medium-sized vehicles and buses are negatively correlated with the average speed of mixed motor vehicle,while the proportion of small vehicles is positively correlated with the average speed of mixed motor vehicle traffic flow.Combining with the real-time operation data of bus GPS,the relation between bus travel time,vehicle type proportion and bus proportion is analyzed under different road sections.Then,the connotation of bus travel time reliability is analysed.The factors affecting the reliability of bus travel time under mixed motor vehicle traffic flow are analyzed from both internal and external aspects.Monte Carlo method is used to calculate the reliability of bus travel time.And the relationship between bus proportion,vehicle type proportion and travel time reliability is explored.A travel time reliability model considering bus proportion and a travel time reliability model considering vehicle type proportion are established.The optimal solutions of the models are solved and verified.The result shows that the higher the proportion of small vehicles on the road,the greater the reliability of bus travel time in different saturation intervals of mixed motor vehicle traffic flow.The larger the bus proportion,the smaller the reliability of bus travel time in different mixed vehicle traffic flow saturation intervals.Finally,taking Fuzhou No.55 and No.96 bus routes as examples,VISSIM is used to simulate the bus operation under the mixed motor vehicle traffic flow composed of different vehicle type proportion and different bus proportion.The result shows that when the bus proportion is fixed at 7%,the bus travel time tends to decrease with the increase of the proportion of small vehicles in different traffic saturation and road sections.And the travel time of buses varies with the proportion of small vehicles,the degree of variation of bus travel time with the change of vehicle type proportion increases with the increase of traffic saturation.When the proportion of vehicles is fixed at 1:2:7 in different road sections and in different traffic saturation intervals,the bus travel time increases with the increase of the bus proportion.And the degree of variation of bus travel time with the change of bus proportion increases with the increase of traffic flow saturation.