Research On The Complexity Of Weighted Urban Bus Network

With the accelerating pace of urbanization, traffic congestion is becoming a major problem in many cities in China. As a convenient, economical and environmental friendly travel mode, bus transportation is becoming more and more attractive to many travelers. Despite its long history of development, bus transport system still have many issues unresolved. As a new approach to researching system organization, the complex network theory presents a brand new platform for study and improving bus transport system.Based on the complex network theory, this thesis first established two types of network topological structures using Chengdu bus transport system as an example, These are the bus geographical network referred as to the Space L, and the bus transfer network referred as to the Space P. On top of that, we added edge weight to the network according to the latitude and longitude coordinates of each bus station and form the corresponding weighted networks. The analysis of the two topological models, both weighted and unweighted allows us to gain deeper understanding of the characteristics of the bus network of Chengdu.When exploring the shortest path for the bus transfer network, we came up with a new algorithm for calculating the relative shortest path for weighted bus transfer network. The new algorithm can guarantee that the path it find be the shortest based on the premise of having minimum transfer times. Through an empirical study, the effectiveness and practicality of the algorithm is confirmed.Lastly, this thesis has conducted a robustness analysis for the Chengdu bus geographical network, by simulating network under situation of random failure and deliberate attacks and determining the corresponding change in network efficiency. For situations like road construction which usually affect the operation of bus network, we develop a bypass strategy for the bus routes affected by a road construction site. Base on the bypass strategy, the bypassing situations over Chengdu geographical network when some stations are under construction are simulated; the efficiency and average shortest path of the bypassing network are calculated. The results indicated that even under situations of having some stations disconnected, the overall network could still maintain a relatively high efficiency by implementing a reasonable bypassing strategy.