The impact of irregular headways on seat availability

Document Type

Journal Article

Publication Date


Subject Area

operations - performance, operations - reliability, operations - capacity


seat availability, reliability, demand uncertainty, irregular dispatching, transit line


This paper introduces seat availability reliability, a new reliability measure that assesses the performance of transit lines. This alternative reliability indicator is defined in terms of the coefficient of variation, which examines the relative deviation of seat availability. An analytical approach is utilized based on the conditional expectation to achieve relationships for the mean and variance of the number of boarding and alighting passengers and seat availability at stops. Furthermore, confidence intervals for seat availability are derived. It is proposed that such information might be useful for traveler information systems. The proposed model is applied to a schematic transit line to show how sensitive seat availability is to headway variation (irregular dispatching) and demand uncertainty


Permission to publish the abstract has been given by Taylor&Francis, copyright remains with them.