Investigating a small-sized bike-sharing system’s impact on transit usage: a synthetic control analysis in Tucson, Arizona

Xiaofeng Li, Yao Jan Wu, Alireza Khani

Research output: Contribution to journalArticlepeer-review


The bike-sharing system (BSS) is an emerging travel mode that has attracted increased attention in recent years. One of the most critical reasons for this increased attention is that the BSS claims to solve the first-mile and last-mile problems, and can be used to connect with existing transit. However, some studies suggest that BSSs could compete with transit rather than collaborating. Previous studies only focused on large-sized BSSs, ignoring an analysis of the impact of small-sized BSSs. To fill this gap, this paper conducted a case study to investigate the impacts of introducing a small-sized BSS on transit (including regular bus, express, and streetcar) usage in Tucson, Arizona. All transit routes are categorized into two groups: treated routes with the defined buffer of BSS and control routes without BSS. Then, the synthetic control method (SCM) is employed to provide an unbiased comparison on the average ridership per stop of the treated transit routes. The ridership data and point-of-interest data are collected and used to synthesize virtual treatment transit routes. The results show that a small-sized BSS generally has a slight impact on the ridership of most transit routes because of the limited coverage. However, the streetcar experiences an increase in ridership and increases by 0.55 passengers as a result of 1 BSS trip. Furthermore, the relationship between a small-sized BSS and transit may be also dependent on whether a transit route can access areas having the densest BSS network. These findings suggest that the role of BSSs in an urban transportation system can be controlled by relocating the locations of BSS stations considering the characteristics of transit routes.

Original languageEnglish (US)
Pages (from-to)441-458
Number of pages18
JournalPublic Transport
Issue number2
StatePublished - Jun 2022

Bibliographical note

Funding Information:
The authors would like to thank the City of Tucson for funding and data support. We would also like to thank Jennifer Toothaker, Francisco Leyva, Andrew Bemis, Kim Okada, and Hyunsoo Noh for providing valuable advice and technical support in this project. Special thanks to Adrian Cottam and Lilly Cottam for their assistance in English proofreading.

Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.


  • Bus
  • Express
  • Ridership
  • Small-sized bike-sharing system
  • Streetcar
  • Synthetic control method


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