Real-Time Public-Transport Operational Tactics Using Synchronized Transfers to Eliminate Vehicle Bunching

Scheduled public transport (PT) service on a defined network often encounters unforeseen variations of arrival times mainly because of traffic problems, unexpected passenger demand, and driver behavior. These variations will create the undesirable vehicle (particularly bus) bunching phenomenon unless a proper control action is introduced. This study develops a methodology to attain optimally real-time control actions to minimize the bunching phenomenon. To this end, a library of selected operational tactics is constructed, for the PT operators, not only to assist in reducing vehicle bunching but also to increase the likelihood of direct (without await) transfers. The library of operational tactics serves as a basis for a process of real-time control actions to maintain the scheduled headway and thus achieving maximal transfer synchronization. The methodology developed, using simulation, is applied to a case study of actual bus routes operated in the region of Auckland, New Zealand. The results imply what tactic to use in real time, what is the optimal control strength, and what is the saving of riding and waiting times in comparison with PT operation without using tactics. The findings show that a significant improvement, in avoiding bunching and increasing the number of direct transfers, is attained by the use of a combination of selected tactics.