Research On The Effectiveness Of One-Way Streets In Urban Network

With the supply and demand of traffic constantly changing and fiercely interacting, most and medium-sized cities have traffic jams to varying degrees. Under the circumstances of increasing traffic demand, many metropolises in china and abroad are now taking effective measures to improve urban traffic conditions. As a simple and effective traffic management measure, one-way street is widely applied in unclogging urban road network and alleviating traffic congestion as it can improve road capacity and traffic speed and reduce traffic accidents, etc. The thesis is aimed at improving the operation efficiency of road network by converting some of roads into one-way street, take into account travelers’ routing decisions comprehensively.Firstly, the thesis summarizes the main research findings from the past studies about urban one-way streets from various perspectives such as the application conditions, the implementation effects, its advantages and disadvantages. Then some part of the theories has been deepened and developed. What’s more, some measures of coping with negative effects of one-way traffic are put forward emphatically.Secondly, Effective planning and implementation of the one-way streets are vital methods to realize the efficiency of traffic network. Lastly, aiming at minimum bypass cost and road saturation and considering the shortest path element, a Bi-level programming model for the effectiveness of the one-way streets is established and Genetic Algorithm is also designed to solve the model. The variables of the upper level programming model are the one-way street design proposal and the optimization objective of the upper programming is to minimize the average road saturation level and the bypass distance. The lower level programming model is to make user equilibrium assignment on the limitation of road capacity and saturation. Through a comparative analysis of real world examples, the author analyzes the traffic conditions on the main and branch roads before and after the optimization of one-way traffic. The result indicates that the average saturation of the main road increases from68.9%to71.3%, while that of branch road decreases from60.1%to71.9%and the bypass time increases only1.7min. Simultaneously, the saturation of the road network distributes more evenly. Furthermore, the conclusion strongly supports the effective implementation of one-way streets in the road network; it also shows the validity of the proposed model and algorithm.Finally, based on the relationship between the one-way streets and carbon emissions, some indicators were proposed to quantify the carbon emissions. Then the one-way streets organization in Chengdu city was taken as an example to show its relationship with carbon emissions. The conclusions can be used as references for the effective implementation and evaluation of one-way streets.