Public Transit Service Reliability Assessment using Two-Fluid Model

Document Type

Journal Article

Publication Date


Subject Area

place - north america, mode - bus, operations - performance, operations - reliability, technology - geographic information systems, planning - methods, planning - service improvement


Public transit, service reliability, GPS data, traffic


This study introduces a traffic flow theory-based reliability indicator to evaluate the inter-city public transit service. The two-fluid theory parameter n that measures the road networks’ resilience to changing traffic is used as a new reliability indicator of public bus service. We compared the performance of the new indicator with the three existing reliability indicators, including on-time performance, with a total of 52 different GO Bus routes to ascertain the usability of the new indicator. The GO Bus service is an inter-city bus service operated by Metrolinx in the Greater Toronto and Hamilton areas in Ontario, Canada. We used 1 month of GO Bus GPS data collected in July 2017 to estimate various public transit reliability indictors. We also investigated the relationship between reliability indicators and selected roadway network characteristics, such as route length, freeway ratio, intersection density along a route, and so forth. The study applied a series of statistical analyses, including principal component analysis, correlation analysis, and z-test using Fisher’s z transformation. The results showed that the proposed two-fluid indicator n can be used as a supplementary reliability indicator for assessing road networks’ resilience in regards to changing traffic flow conditions. The new indicator provided additional insights for inter-city bus service operators for initiating communication with roadway governing agencies for the purpose of improving road networks to further improve public transit service reliability.


Permission to publish the abstract has been given by SAGE, copyright remains with them.