Reliable frequency determination: Incorporating information on service uncertainty when setting dispatching headways

Abstract

Frequency setting requires the determination of the dispatching headways of all bus lines in a city network and constitutes the main activity in the tactical planning of public transport operations. Determining the dispatching headways of bus services in a city network is a multi-criteria problem that typically involves balancing between passenger demand coverage and operational costs. In this study, the problem of setting the optimal dispatching headways is formulated with the explicit consideration of operational variability issues for mitigating the adverse effects of passenger demand and travel time variations inherent to bus operations. The proposed model for setting the dispatching headways of bus lines considers the demand, headway and travel time variations along every section of each bus route for different times of the day, as well as operational costs, vehicle capacity and fleet size constraints. We first formulate the problem while accounting for the consequences of variability in service operations. The resulting optimization problem is then solved by employing a Branch and Bound approach together with Sequential Quadratic Programming in order to find the optimal dispatching headway for each bus line. Experimental results demonstrate (a) the improvement potential of the base case dispatching headways when considering the service reliability; (b) the sensitivity of the determined dispatching headways to changes in different criteria, such as passenger demand and/or bus running costs, and (c) the convergence accuracy of the proposed solution method when compared to heuristic approaches.

Multi-constrained bus holding control in time windows with branch and bound and alternating minimization

“…In general, the daily operations of a bus line are formed on the basis of an extensive tactical planning process that involves the planning of bus frequencies, crew and vehicle schedules (Kepaptsoglou and Karlaftis 2009;Farahani et al 2013;Gkiotsalitis and Cats 2018;Gkiotsalitis, Wu, and Cats 2019). During the tactical planning phase, the dispatching time of each bus trip is defined and the daily timetable is generated.…”

Simulation-Driven Optimization of Urban Bus Transport

“…Especially from the tactical planning perspective, the availability of AVLS and ETM data helps improve the OD demand estimation and thereby timetable design. In Gkiotsalitis and Cats [9], dispatch headways are computed through solution of a quadratic optimization problem considering the demand, headway and travel time variations for different times of the day, operational costs, vehicle capacity and fleet constraints. Further Wang et al [10] consider the waiting time minimization problem for large scale data set of passenger boarding times in order to generate optimal dispatch schedules.…”

Bus holding control of running buses in time windows

“…In general, the daily operations of a bus line are formed on the basis of an extensive tactical planning process that involves the planning of bus frequencies, crew scheduling and several other constraints such as the minimum layover times between successive trips and the permitted dispatching headway ranges (Kepaptsoglou and Karlaftis (7), Farahani et al (8), Gkiotsalitis and Cats (9), Gkiotsalitis and Cats (10)). During the tactical planning phase, the dispatching time of each bus trip is defined and the daily timetable is generated.…”