Document Type


Publication Date




Publication Title

Accident Analysis and Prevention




(107281) 1-11 pp.


Despite many research efforts on ride-hailing services and taxis, limited studies have compared the safety performance of the two modes. A major challenge is the need for reliable mode-specific exposure data to model their safety outcomes. Moreover, crash frequencies of the two modes by injury severities tend to be spatially and inherently correlated. To fully address these issues, this study proposes a novel multivariate conditional autoregressive model considering measurement errors in mode-specific exposures (MVCARME). More specially, a classical measurement error structure is used to accommodate the uncertainty of mode-specific exposures estimated, and a multivariate spatial specification is adopted to capture potential spatial and inherent correlations. The model estimation is accelerated by an integrated nest Laplace approximation method. The census tracts in the city of Chicago are set as the spatial analysis unit. The mode-specific exposures (vehicle-mile-traveled) in each census tract are estimated by trip assignments using ride-hailing and taxi trip data in 2019. The modeling results indicate that both ride-hailing crashes and taxi crashes are positively associated with transportation factors (e.g., vehicle-mile-traveled, mode-specific vehicle-mile-traveled, and traffic signal numbers), land use factors (i.e., number of educational and alcohol-related sites), and demographic factors (e.g., median household income, transit ratio, and walk ratio). By comparison, the proposed model outperforms the others (i.e., negative binomial models and multivariate conditional autoregressive model) by yielding the lowest deviance information criterion (DIC), Watanabe-Akaike information criterion (WAIC), mean absolute error (MAE), and root-mean-square error (RMSE). According to the results of t-tests, ride-hailing services are found to be prone to a higher risk of minor injury crashes compared with taxis, despite no significant difference between the risks of severe injury crashes. Methodologically, this study adds to the literature a robust safety evaluation approach for comparing crash risks of different modes. At the same time, practically, it provides researchers, practitioners, and policy-makers insights into the safety management of various mobility alternatives.


© The Authors.

Included with author permission.


This is a preprint article. It offers immediate access but has not been peer reviewed.

Final published version of the article has been published in the journal Accident Analysis and Prevention and be accessed at


0000-0002-8191-2786 (Xie), 0000-0003-2808-8852 (Yang)

Original Publication Citation

Zhai, G., Xie, K., Yang, H., & Yang, D. (2023). Are ride-hailing services safer than taxis? A multivariate spatial approach with accommodation of exposure uncertainty. Accident Analysis & Prevention, 193, Article 107281.