Study On Transit Signal Priority Strategies Based On BRT System With Median Stations

As known, Transit Oriented Development (TOD) has been widely presented by traffic planners and managers around the world so as to mitigate urban traffic congestion. This strategy is to develop an efficient and convenient public transit system. Against this background, as the public transport mode of high efficient, convenient, safe, and economic, the Bus Rapid Transit (BRT) system has been widely recognized and developed quickly. However, the development of BRT transit priority technology further enhances the benefit of the BRT system. Under limited road and traffic resource situation, Transit signal priority (TSP), one of the most efficient traffic control methods, can enhance BRT service and operations by the usage of effective strategies, good programs and comprehensive functions.Therefore, based on a great deal of relevant literature and the previous related studies, this research is focused on the TSP controls of BRT system via the methodologies of traffic engineering, automatic control, traffic simulation, network optimization and computer science etc. In terms of the problems of BRT system, this paper will propose innovative TSP control approaches.Firstly, the paper analyses the key variables which cause BRT buses delays based on BRT system operator characteristics and structural features of most cities in China. Furthermore, through synthesizing results of previous studies on the BRT signal priority control system and comparing with the signal priority strategies based on the headway in the past, which only consider the relationship between the headway of buses and the planned departure interval, an innovative signal priority strategy based on the headway is proposed. The signal priority control strategy proposed by this paper considers the headway between three adjacent BRT buses in one route at the same time, which will largely improve the uniformity of the BRT buses.Secondly, in the Bus Rapid Transit (BRT) systems of having central island stations near to the signalized intersection for the accessibility to pedestrians, high bus arrival rate may cause Getting up or stopping the bus many times in short distance and queue spillback and consequently block the nearby intersection due to the limited storage capacity of the stations.Therefore, in terms of above problems, this paper presents a real-time TSP control system including both priority control strategies (green extension and red truncation) and suppression control strategies (green truncation and red extension) based on the headway. And the paper also calculated the benefit of executing transit signal priority.According to the established TSP control approaches of BRT systems with central island stations near to the signalized intersection, a TSP model and a TSP control implementation process is developed. And the developed TSP control algorithm is programmed to validate it based on VISSIM, VB.Net and MYSQL. Then the reasonability and feasibility of developed TSP model is embodied in the actual road network in Jinan. According to the results of simulation, the developed control logic could reduce the bus passenger waiting time under without increasing the total intersection delay.The proposed TSP control based on the headway could improve regularity of bus vehicles at the next bus stop in order to reduce the bus passenger waiting time. And the real-time TSP control system including both priority control strategies and suppression control strategies not only can reduce the delay of the bus passengers, but can limit queue spillback occurrence at stations. The BRT system TSP strategy and optimization model is a profitable exploration on transit signal priority theory and method, which provides certain theory and technical assistance for bus operators and traffic managers in bus scheduling and signal design.