Variation in bus transit service: understanding the impacts of various improvement strategies on transit service reliability

Transit agencies wishing to offer reliable service with less variability compared to schedules face several challenges, encouraging them to employ various strategies. While previous research has considered the effects of various strategies on running time, there has been little effort to understand their impacts on reliability of service. This article examines the impacts of various improvement strategies, implemented by Société de Transport de Montréal (STM) along one of its heavily utilized bus routes, on running time deviation from schedule, variation in running time, and variation in running time deviation from schedules. These strategies have been implemented at different time points over the past three years. They include, chronologically ordered, implementation of a smart card fare collection system, operation of a reserved bus lane, introduction of limited-stop bus service, use of articulated buses, and operation of transit signal priority (TSP). This study uses automatic vehicle location (AVL) and automatic passenger count (APC) systems at the bus route segment level of analysis. The introduction of a smart card fare collection system increased bus running time and service variation. Articulated buses, limited-stop bus service and reserved bus lanes have mixed effects on variation in comparison to the running time changes, while TSP did not show an impact on variations in our study. This study offers transit agencies and schedulers a better understanding of the effects of various strategies on different aspects of service variation, which are important components of transit service reliability