Investigating the potential of aggregated mobility indices for inferring public transport ridership changes

Abstract

ICT mobility indices derived from information and communications technologies have recently emerged as a new data source for transport planners. Despite the popularity of these indices, it remains largely untested whether they can provide a reasonable characterisation of actual PT ridership changes. This study aims to address this research gap by investigating the reliability of using ICT mobility indices for inferring PT ridership changes by offering the first rigorous benchmarking between them and ridership data derived from smart card validations and tickets. For the comparison, we use monthly and daily ridership data from 12 cities worldwide and two ICT indices shared globally by Google and Apple during periods of major change in 2020-22. The comparative analysis revealed that the index based on human mobility (Google) exhibited a notable alignment with the trends reported by ridership data. Moreover, we demonstrated that ICT mobility indices can also complement data from smart card records when ticketing is missing or of doubtful quality.