Projecting travelers into a world of self-driving vehicles: estimating travel behavior implications via a naturalistic experiment


Automated driving technologies are currently penetrating the market, and the coming fully autonomous cars will have far-reaching, yet largely unknown, implications. A critical unknown is the impact on traveler behavior, which in turn impacts sustainability, the economy, and wellbeing. Most behavioral studies, to date, either focus on safety and human factors (driving simulators; test beds), assume travel behavior implications (microsimulators; network analysis), or ask about hypothetical scenarios that are unfamiliar to the subjects (stated preference studies). Here we present a different approach, which is to use a naturalistic experiment to project people into a world of self-driving cars. We mimic potential life with a privately-owned self-driving vehicle by providing 60 h of free chauffeur service for each participating household for use within a 7-day period. We seek to understand the changes in travel behavior as the subjects adjust their travel and activities during the chauffeur week when, as in a self-driving vehicle, they are explicitly relieved of the driving task. In this first pilot application, our sample consisted of 13 subjects from the San Francisco Bay area, drawn from three cohorts: millennials, families, and retirees. We tracked each subject’s travel for 3 weeks (the chauffeur week, 1 week before and 1 week after) and conducted surveys and interviews. During the chauffeur week, we observed sizable increases in vehicle-miles traveled and number of trips, with a more pronounced increase in trips made in the evening and for longer distances and a substantial proportion of “zero-occupancy” vehicle-miles traveled.

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    A complement to our experiment would be to investigate the travel behavior impacts if people were to make use of a shared fleet of self-driving vehicles (rather than private ownership), and this is left for future research.


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We thank Yoram Shiftan and Kostas Goulias for earlier discussions regarding the experimental design.

Author information

MH: Literature review, Data collection, Data analysis, Manuscript writing and editing. YX: Data collection. GC: Literature review, Manuscript writing and editing. PM: Literature review, Manuscript writing and editing. JW: Literature review, Data analysis, Manuscript writing and editing.

Correspondence to Mustapha Harb.

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Harb, M., Xiao, Y., Circella, G. et al. Projecting travelers into a world of self-driving vehicles: estimating travel behavior implications via a naturalistic experiment. Transportation 45, 1671–1685 (2018).

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  • Travel behavior
  • Self-driving vehicles
  • Naturalistic experiment
  • Chauffeur
  • VMT