Bus Rapid Transit Signal Priority Along Corridors Based On Pre-timed Signal Coordination

Implementing BRT signal priority is an important measure to improve the service quality of public transit and to put the strategy of giving priority to develop public transit.The necessary derivative research project after BRT route design is implementing BRT signal priority based on signal coordination along corridors.This paper provided priority treatments include green extension,early green,phase insertion,and developed a BRT signal priority method along corridors based on pre-timed signal coordination which is aimed at increasing the operating speed of BRT vehicle,while took the impact for corridors into consideration.The shortcomings of existing studies include:(1)green time reallocation algorithm is lack of equity;(2)negative effect of phase insertion is short of counter measures;(3)unconditional recovery method will harm the performance of coordination and priority;(4)the method of pausing priority treatment while implementing recovery limit the room for improvement of priority performance.To address the issues above,there are several innovative technical features of this research:(1)developed the green time reallocation algorithm which is suitable for signal priority along corridors taking vertical equity belonged to the principles of microeconomics aimed to compress or compensate phase green time equally;(2)developed the solution of phase insertion treatment along corridors using multiple strategies to coordinate a response to the adverse impact of phase insertion;(3)developed the conditional recovery mechanism only focuses on the cycle which has implemented phase insertion;(4)developed the integration mechanism of priority and recovery which treats recovery process as a temporary background timing plan adjustment,allowed to implement priority treatment while recovering,and discovered the potential for priority performance improvement.According to the simulation result,it can be concluded that the innovations above are superior to their conventional methods.Compared with the condition that does not implement signal priority,this BRT signal priority method along corridors reduces the system-wide delay by no more than 5%,increases the total travel time of coordinated phase by no more than 2%,improves the speed of BRT vehicle running at a single line by more than 39%.It is believe that this signal priority method could significantly improve the service quality of BRT,while control the impact for corridors at an acceptable level.The comprehensive performance of this signal priority method is worthy to be affirmed.The contributions of this paper are:(1)proper green time adjustment algorithm is a main fulcrum on reducing the adverse impact of signal priority;(2)the techniques which are appropriate for isolated intersection should be treated and applied carefully along corridors;(3)the phase insertion treatment has appreciable benefit along corridors and its negative effect could be controlled.So phase insertion treatment deserves to be carried out and be research in depth;(4)the conditional recovery mechanism and the integration mechanism of priority and recovery have their own advantages when it comes to traffic performance,have existence value in engineering practice,and there are sufficient reasons to discuss and further develop them.