Measuring Bus Service Reliability: An Example of Bus Rapid Transit in Changzhou

The objective of this paper is to analyze service reliability of bus rapid transit (BRT) taking Changzhou BRT as an example. Headway irregularity, potential waiting time, equivalent waiting time, and reliability buffer time are recommended to measure service reliability of BRT. Temporal and spatial distributions and comparisons are analyzed. Findings are that passengers of Changzhou BRT need to budget, on average, an extra 3–5 minutes beyond their typical journey time for selected origin-destination pairs to ensure on-time arrival at destinations with 95% probability. Extra time budgeted for bus waiting beyond mean waiting time contributes to more than 80 percent of extra time budgeted for a journey, while only 20 percent is budgeted for in-vehicle travel time. Service reliability is best near a route’s origin terminal and gradually deteriorates along the route, then improves when approaching the route’s end. Introduction Bus rapid transit (BRT) combines the efficiency and reliability of a rail service with the operating flexibility and lower cost of a conventional bus service. It has been implemented throughout Latin America, North America, Europe, Southeast Asia, Australia, China, and now, increasingly, in Africa and India (Deng and Nelson 2011). Journal of Public Transportation, Vol. 17, No. 2, 2014 114 In China, BRT has expanded faster than in any other regions over the last five years, with 320 km of BRT systems in 13 cities (Fjellstrom 2010). Service reliability of a transit system has significant impacts on its providers as well as existing and potential users (Cham 2006). The objective of this paper is to analyze service reliability of BRT taking Changzhou BRT as an example. Specifically, issues including the amount of time passengers need to wait, on average, and the amount of extra time passengers need to budget beyond typical wait time and journey time, on average. Temporal and spatial distributions of measures and comparisons between measures are examined. Potential wait time, which is proposed to measure service reliability but has not been applied yet, is put into practice in this paper. Some suggestions for improving service reliability of Changzhou BRT are brought forward. The framework for analyzing service reliability of Changzhou BRT includes measures and analysis dimensions that can be applied to other BRT systems. Literature Review Service reliability is defined as “the invariability of service attributes which influence the decision of travelers and transportation providers” (Abkowitz et al. 1978). The ability of transport operators to understand and improve reliability relies on their ability to measure it (Uniman 2009). Service reliability can be measured from multi-perspectives based on multi-levels. Measures from operators’ perspectives mainly include on-time performance (OTP) and headway regularity (Cham 2006, Kittelson & Associates, Inc. et al. 2003). OTP is the fraction of services with schedule deviation within some thresholds (Ryus 2003). Headway regularity is defined in terms of the fraction of observed headways that are within some absolute or relative deviation from the scheduled headway (Cramer 2008). Furth et al. (2006) consider it a coefficient of variation of headway, which is the standard deviation of headway divided by the mean. Measures from the passenger perspective include waiting time-related measures such as excess waiting time, potential waiting time, and equivalent waiting time. They also contain journey time-related measures such as excess journey time, reliability buffer time, and excess reliability buffer time. Excess waiting time represents the extra amount of time a passenger waits, on average, beyond the scheduled waiting time (Furth and Muller 2006). To have a high probability of arrival at their destinations on time, passengers must plan on waiting longer than the mean waiting time. The 95th percentile waiting time is often interpreted as budgeted waiting time, guaranteeing arrival at their destinations on time