Abstract
This seminar presents an examination of the inter-relationship between household vehicle ownership and ridehailing use frequency. Both variables constitute important mobility choices with significant implications for the future of transport. While it is generally known that these two behavioral choices are inversely related to one another, the direction of causality is rather ambiguous. Do vehicle ownership levels affect ridehailing use frequency, or does the adoption and use of ridehailing services affect vehicle ownership? If ridehailing services affect vehicle ownership, then it is plausible that a future of mobility-as-a-service would be characterized by lower levels of vehicle ownership. To explore the degree to which these causal relationships are prevalent in the population, a joint latent segmentation model system is formulated and estimated on a 3500-respondent survey data set collected in four automobile-oriented metropolitan areas of the United States. The latent segmentation model system recognizes that the causal structures driving mobility choices of individuals are not directly observed. Model estimation results show that 58 percent of the survey sample follow the causal structure in which ridehailing use frequency affects vehicle ownership. This finding suggests that there is considerable structural heterogeneity in the population with respect to causal structures, and that ridehailing use does indeed hold considerable promise to effect changes in private vehicle ownership in the future.

About the Speaker
Ram Pendyala is a professor of transportation systems and the Director of the School of Sustainable Engineering and the Built Environment at Arizona State University. He also serves as the Director of TOMNET, a USDOT-funded Tier 1 University Transportation Center.  He has previously served on the Civil & Environmental Engineering faculty at the University of South Florida and Georgia Tech.  His expertise lies in the study of activity-travel behavior and understanding the role of various factors in shaping human mobility choices. He has published extensively and held leadership positions in the Transportation Research Board Technical Activities Division, including service as Chair of the Traveler Behavior and Values Committee, Travel Analysis Methods Section, and Planning and Environment Group. He has also previously served as the Chair, Vice-chair, and Secretary/Treasurer of the International Association for Travel Behaviour Research. He has his PhD and MS degrees from the University of California at Davis, and his B.Tech. in Civil Engineering from the Indian Institute of Technology-Madras.

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