Research On The Link Travel Time At Urban Roads Under Different Organizations

In recent years, the traffic problems in big cities have become more and moreserious. Traffic jam, traffic accidents have become bottleneck restraining thedevelopment of a city. In order to alleviate traffic jam on urban roads, to enhancetransportation circulation efficiency, and to decrease traffic accidents, measures areapplied to resolve the traffic problems from these aspects to perfect road networks,and to strengthen traffic management. Under the condition that the road networkconstructions in big cities gradually better at present, scientific traffic planning,design and management seem to be more important. The evaluation of trafficmanagement project is the core of urban traffic management and planning, onwhich traffic assignment is based as the key to the project evaluation. So in thisdissertation, the preliminary parameter of link travel time is chosen as for the goalin traffic assignment.There has been a lot of research on link travel time function in the past. In thisdissertation, analysis is conducted on the factors that affect travel time by summingup and absorbing from the past research results. Link travel time functions areestablished on the basis of real traffic conditions in China. Because of too manyfactors influencing link travel time, several major factors are under analysis in lightof traffic organization. It also includes interpretation of different trafficorganization forms affecting link travel time, with travel time function modelrectified. In the paper, it firstly defines link travel time, and establishes linkspeed-flow relation to obtain basic travel time on urban roads. In the research, fielddata are adopted to analyze the relation between speed and flow on the roads. It isfound that speed-flow relation at urban roads does not accord with traditionalfunction model. Based on the,research of travel time, emphasis is laid on analyzingoperation characteristic of traffic flow, which is affected by bus stops, mixed trafficenvironment of motor vehicles and non-motorized vehicles, and curb parking, andson on. It makes use of queuing theory, traffic wave theory, and clearance theory toestablish the delay model of traffic flow. Then it gives the travel time functionmodel under these influence factors. In this dissertation, it mainly consists of thefollowing chapters:(1) Research on basic travel time at urban road linksBy reviewing the previous speed-flow relation models, and adopting field dataon the basic road links of Changchun City, the speed variation tendency with flowis described, speed-flow relation of urban street is analyzed with and withoutmedian.(2) Research on link travel time affected by bus.In this paper, operation characteristic of bus and its impact on traffic flow areanalyzed. As to one-way and one-lane roads, it analyzes the course that buses affect,and the travel time function model are established. The model is validated withVissim. As to two-way and two-lane roads, operation characteristic of vehicles isunique. In real situation, vehicles usually use the opposing lane to bypass the busesahead. On the basis of analyzing bus operation characteristic, queuing theory,clearance theory, and the arrival curve of the vehicles are combined to set up thedelay models under different flows. Furthermore, travel time function model isproduced.(3) Research on link travel time affected by non-motorized vehicles.Aiming at traffic flow characteristics of mixed motorized vehicles andnon-motorized vehicles, the reasons why this mixed traffic flow interferes witheach other are analyzed. From three respects of traffic characteristic as bicycles, thefactor affecting vehicle flows and the interference courses, it explains themechanism of non-motorized vehicle impact on traffic flow. According to the loaddegree of the non-motor lane and arrival of vehicles, it is divided the impact ontravel time into four situations. Then the present delay model is utilized to calibratethe travel time function model of the roads affected by non-motorized vehicles.(4) Research on the link travel time affected by curbside parking.It is analyzed the curb parking impact on traffic flow on urban roads. Utilizingthe present delay model, the travel time function model of the one-way andone-lane road are presented. Stop time and operation characteristic of traffic streamare analyzed by comparing with bus impact. Combined with the vehiclearrive-depart graphic, travel time function model of curb parking is given.In the end, the findings and achievements are summarized, and the issues forfurther research are brought forward.The travel time function model put forward in the paper can be used not onlyfor transportation management project evaluation, but also for traffic flowassignment in transportation planning. At the same time, the relation between speedand flow is the essential condition to classify and certify road service levels. In thispaper, study on speed-flow relation, and analysis on bus and curb parking can serveas theoretical supports for traffic managers.