Large Urban Road Network Reliability Evaluation

Presently, Growing traffic congestion, traffic disturbance and traffic accidents have been becoming the stubborn disease that restricts the social improvement and economic development of a region. It has become a global problem that will affect the exertion of the urban function and the sustaining development of the urban, so it has been put forward more requirements on the dealing ability of the urban traffic networks with the routine and the accidental traffic problems.The road network is the basement of the traffic network. The network reliability and the element importance index of the road network are the important quantitative indexes, which are related with the decision on the layout, design, evaluation, reconstruction and repair of the road traffic network system and the network elements. Due to the NP hard on the minimal paths and the disjoint minimal paths, and the logical expression of the out door behaviors of the human being and the selecting principals of the rational path set, it is always the choke points on the system reliability evaluation and the element importance analysis of the local large road network traffic evaluation.For these, this thesis puts emphasis on the following tasks:1) A new method is introduced on the calculating the reliability of the road network of a large urban area by means of the searching of the rational paths. It is edited a program by using the C language to search the rational paths and calculating the system reliability of a large road network, it is proved that the NP hard is efficiently avoided when the rational paths are searching.2) Two-phases-four-stages Technical Assessment Method has been forward developed. Element topology importance and element design importance are defined for the topological layout stage and structural design stage. Comparing with the element probability importance, the element topology importance and element design importance can show more exactly the positions of the bottleneck elements during the topology layout stage and structural design stage of the road network.3) A decision analysis is produced for the traffic assessment and reconstruction at a representative region of Zhengzhou city. Qualitative and quantitative assessment is done to locate the bottleneck unit, the sub-network, the road segments and or the crosses, of the road network at topological layout and structural design stages. Comparing with the practical situation of the area, it is validated the rationality of the suggested method. And some constructive suggestions have been made for the planning, reconstructing and extending of the local road network of Zhengzhou city.