A Travel Time Reliability-based Approach To The Estimation Of Traffic Conditions For The Beijing Central Town Road Network

Traffic conditions of the road network in Beijing have been deteriorating continuously, which have become a research focus in the area of traffic engineering. The emerging and development of the concept of the road network reliability provides a entirely new measure for evaluating traffic conditions of the road network, within which the travel time reliability is a reliability index that has been given the most attention with more advanced research accomplished. However, the research about the travel time reliability so far has mainly focused on the theoretical side, or been applied to some small-scaled road networks or self-defined road networks, in the absence of pratical applications to the real-world case studies. In this context, the research in this thesis intends to use the Beijing central town road network, including Beijing second-ring road and the principal arterials within the second-ring, as the case study network. With the floating car data as the data source, it calculates the Coefficient of Variations (CVs) on each road segment using the standard statistical method. Then, it normalizes CVs, and subsequently uses the Travel Time Stability Index (SI) as a measure to represent the travel time reliability on each road segment. Further, the thesis uses both the weighted average method and the state-tree search method to calculate the travel time reliability for the entire road network in order to evaluate its traffic conditions. The thesis calculates the travel time reliability characteristics for different periods of the day, differences of travel time reliabilities for different days, travel time reliabilities for different classified roads, and for specific areas. After that, it evaluates the traffic conditions of the Beijing central town road network by analyzing the results of the reliabilities. Finally, the thesis uses the speed as a measure to compare the weighted average method and state-tree search method, in terms of their differences and adapabilities in calculating the travel time reliability for road networks.