Mahmood Mahmoodi Nesheli

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.

Optimal Synchronized Transfers in Schedule-Based Public Transport Networks Using Online Operational Tactics

Synchronized transfers in schedule-based public transport (PT) networks are used to reduce interroute or intermodal passenger transfer waiting time and provide a well-connected service. However, in practice, synchronized transfers do not always materialize because of some stochastic and uncertain factors, such as traffic disturbances and disruptions, fluctuations in passenger demand, and erroneous behavior of PT drivers. As a result, missed direct transfers not only frustrate existing users but also discourage potential passengers from using PT service. This work presents an optimization procedure based on a model predictive control (MPC) to increase the actual occurrence of synchronized transfers in schedule-based PT networks. The procedure aims to reduce the uncertainty of meetings between PT vehicles. MPC uses selected online operational tactics based on real-time data, such as skip stop, speed change, and holding. First a library of operational tactics was built to serve as a basis for the sequential receding horizon control process in the MPC. Then, an event activity network with dynamic moving elements was constructed to represent the logical process of the PT transfer synchronization problem. The MPC procedure for a real-time deployment of operational tactics was explicated. A detailed example was used as an expository device to illustrate the procedure developed, along with a real-life example from Auckland, New Zealand.

Use of Real-Time Operational Tactics to Synchronize Transfers in Headway-Based Public Transport Service

The problem of applying efficient vehicle synchronization at transfer points was addressed. To reduce the waiting time of transferring passengers and to provide an integrated, well-connected, public transport (PT) service, maximal synchronized transfers were employed at the planning level. However, at the operation level, synchronized transfers do not always appear because of certain stochastic and uncertain factors, such as traffic disturbances and disruptions, fluctuations of passenger demand, and the erroneous behavior of PT drivers. These factors can lead to deterioration in system reliability, missed transfers, and passenger frustration. This work presents a real-time tactic-based control (TBC) procedure to increase the service reliability and actual occurrence of synchronized transfers in a headway-based PT system. The procedure aims at minimizing additional travel time for passengers and reducing the uncertainty of meetings between PT vehicles. The TBC procedure uses selected online operational tactics, such as holding, boarding limits, and skipping stops, all of which are based on real-time data. A library of operational tactics was first built to serve as a basis for the real-time decision-making process in TBC. Then, an extensive analysis framework for event-based activity simulation with dynamic moving elements was constructed to represent the logical process of the problem of PT transfer synchronization. A case study of the Auckland PT system is described for assessing the methodology developed. The results showed improvements of system performance and yielded new findings on what control policy to use in different scenarios.

Real-Time Public Transport Operations

Modern public transport (PT) operations have evolved into a complex multimodal system in which small-scale disorder can propagate. Large-scale disruptions to passengers and PT agencies result. Various studies have been developed to model PT control at the operational level; however, the main downside of possible real-time control actions is the lack of intelligent modeling and a systematic process that can activate such actions immediately. This study presents a real-time control procedure to increase service reliability and to improve successful coordinated transfers in a complex PT system. The developed method aims at minimizing total travel time for passengers and reducing the uncertainty of meetings between PT vehicles. A library of operational tactics is first built to serve as a basis of the real-time decision-making process. The methodology developed is applied to a real-life case study in Auckland, New Zealand. The results showed improvements in system performance and confirmed the use of real-time control actions to maintain reliable PT service.