Measuring Route Travel Time Reliability in an Urban Rail Transit Network

Different from an urban road traffic system, an urban rail transit (URT) system operates on a relatively punctual schedule. However, as urban rail transit networks (URTNs) expand and become increasingly complex, the reliability of route travel time (RTT) between origin and destination (OD) stations tends to decline. As a result, passengers begin to consider the route travel time reliability (RTTR) an important factor influencing their route choices. Although numerous studies have decomposed RTT in URTNs into several parts and calculate respectively using massive data from automatic fare collection (AFC) and automatic train supervision (ATS) systems, few have addressed the issue of travel time reliability (TTR) in URTNs. This paper introduces a refined method for calculating RTT in URTNs by incorporating the impact of peak hours. Additionally, it presents a framework for identifying and quantifying RTTR based on the RTT fitting results. Subsequently, a novel and standardized methodology for measuring RTTR in URTNs is proposed using both the standard deviation (SD) and buffer index (BI). An empirical study on the Beijing URTN is conducted to reveal the characteristics of RTTR in URTNs and its disparities between peak and off-peak hours. Finally, the paper suggests implementing RTTR in the daily operation of URTNs to assist passengers in making well-informed travel decisions and to enhance the service quality of URTNs.