Comparative Study On The Urban Road Network Robustness

With the continuous improvement of the economic level, the supply of the urban road network can not meet the needs of urban transportation development, making urban road network always in traffic jams or even traffic paralysis. Traffic congestion and traffic gridlock will inevitably affect the traveling public. In addition, traffic accidents and other emergencies such as natural disasters also often puzzle the normal traveling public. Therefore, how to maintain the urban road network connectivity capability becomes one of the major problems to be solved in the urban road network. The definition of the robustness of the urban road network is the capacity to maintain its connectivity in the emergency action, which is directly related to the basic question that whether it can still meet people’s transportation needs under the impact of accidents, traffic congestion, natural disasters and other emergencies. Therefore, this paper puts forward the urban road network robustness study.This paper is based on the complex network theory, so this paper trys to summarize and generalize the complex network theory and its mathematical tool“graph theory”. Two areas of urban road network in Changsha and Xi’an are chosen to be modeled and analyzed by the software Pajek, so some of the features of the network, the similarities and differences between the two networks can be gotten. The two networks are both small-world networks, and in their initial states, the connectivities are similar, but the degree distributionsof the two are different.This paper studies robustnesses of the newly built model in random attacks and deliberate attacks. Robustness evaluation indicators are established by two times of selection and optimization. The first time is to choose and optimize connectivity-related indexes in the basic statistical parameters of complex networks; the second time is to choose robustness indexes from the resulting indicators from the first selection and optimization, considering the special structure of the urban road network and differences between random attacks and deliberate attack tests. These chosen indexes should be merged and the meged indicators are the needed evaluation indicators. The establishment of these indicators can fill the gaps in the urban road network robustness research and support robustness research of urban road network. It can also make the robustness of different road network can be compared, and thus some improvement measures of the urban road network robustness can be put forward, which can give some suggestions to adjust and plan the road network.