Study About Bus Transit Support Technologies On Urban Corridors

Traffic congestion has become a serious issue that perplexing cities in China and even the world. This issue cannot be well alleviated by constructing more urban roads, inhibiting the growth of cars and guiding urban traffic flows. Under this situation, many researchers in transportation field have begun to consider the issue from the perspective of optimizing the structure of urban transport. They have put forward relevant concepts such as "Bus Priority" and "Transit-Oriented City", namely raising the proportion of transit trip mode, especially the trip mode of conventional public transit. However, due to long travel time, non-ideal reliability and low ride comfort, conventional public transit does not yet have much attraction to urban residents. Therefore it needs to be improved by specific transit support technologies.Based on the National High Technology Research and Development Program (863 program) "Traffic State Perception Measures and Urban Main Bus Priority Key Technologies" (2012AA112304), bus transit support technologies on urban corridors are systemically studied in this paper, focusing on bus travel time characteristics and bus coordination on corridors, coordination of mid-block pedestrian crossings, the influence trend and rapid disposal of bus abnormal states. The main contents of this paper are as follows:(1) Relevant concepts of multiple bus lines are proposed, characteristics of travel time at links, stations and traffic signals for multiple bus lines are analyzed, as well as characteristics of bus frequency (headway) and capacity. And distribution functions of bus travel time at links, stops and bus headway at the entrance of corridor are obtained. The data collected from Zhongshan North Street in the city of Nanjing is taken for an example to validate the methods of bus travel time characteristic analysis on corridors.(2) The advantage of overlapping-phase mode compared to symmetry-phase mode and approach-specific-phase mode at signal intersection is analyzed. The determining methods of common cycle time and green splits are discussed based on overlapping-phase mode, and the concepts of offsets in bus coordination are analyzed. Also the scheme of phase structure and phase sequence suitable for bus coordination on corridors is proposed.(3) By introducing the propagation line of startup-wave in the analysis method of the conventional delay triangle, the indexes of bus delay, stop times and travel time at traffic signal are calculated to evaluate the effects of bus coordination. The process of bus coordinate on corridors is detailed by comprehensively considering distribution pattern, stop settings, travel time, frequency (headway) and capacity of multiple bus lines. Optimization methods of offsets in bus coordination based on genetic algorithm are also put forward. Methods of bus coordination are applied to Zhongshan North Street in the city of Nanjing. Common cycle time, green splits, offsets and other key parameters on this corridor are optimized. The results show that methods in this paper can significantly improve bus operating efficiency on corridors.(4) Coordination of mid-block pedestrian crossings is studied by considering pedestrian extreme waiting time. Green-wave coordination for actuated single and double phase mid-block crossings is put forward, and is respectively applied to road sections on Zhongshan North Street and Jiangdong Mid Road in the city of Nanjing. The result show that actuated mid-block pedestrian crossings can be effectively coordinated by using these methods and pedestrian waiting time can also be guaranteed not to exceed its maximum tolerance. Besides, aiming at the conflict between non-motor vehicles and bus passengers at the bus stop, layout method of signal lamp for mid-block non-motor vehicles is presented. Aiming at mutual conflict between pedestrians, non-motor vehicles and motor vehicles at intersections, phase design method and signal timing strategy are presented.(5) Bus delay propagation model is formulated and evaluation indexes of bus service level including bus headway, bus travel time, passenger waiting time and passenger comfort are selected to analyze the influence trend of three kinds of bus abnormal states:bus line congestion, sudden increase of passenger volume and bus line jam abnormity. The effectiveness evaluation of three rapid disposal methods of abnormal states, including changing bus operation headways, adding local bus and adjusting bus path, is also carried on.