Factors that affect the evolution of headway variability along an urban bus service.

Abstract

This paper explores new methods for regression models to understand the evolution of headway irregularity of public transport services. In particular, this article is structured around an urban bus service context. This is relevant as headway variability has an important effect on travel time reliability. To do so, a Dynamic Panel Model was estimated to account for serial correlation, which is a novel approach in this context. The coefficient of variation of headways was selected as the dependent variable due to its direct relationship with excess waiting time. The results indicate that the most significant source of headway irregularity is the dispatch at the terminals. The irregularity of uneven dispatches propagates and worsens downstream. To prevent headway variability increasing, the most effective measures are segregated corridors and off-board payment stops. This should be useful to orient interventions in the system’s operations, infrastructure, and contracts that will improve reliability the most.