Household Vehicle Utilization

ABSTRACT: In addition to confirming many perceptions about the ownership, acquisition and utilization patterns of different types of vehicles, this analysis brings out some subtle differences and similarities among the vehicle types. The analysis results indicate a greater propensity to acquire and use larger vehicles such as minivans, sports utility vehicles and pickup trucks among certain socio-demographic segments of population. Increased ownership and use of vans and SUVs, and their usage as personal vehicles rather than just work vehicles warrants a need to revise vehicle type specific policies, transportation planning and control measures.

The report describes a comprehensive vehicle fleet composition, utilization, and evolution simulator that can be used to forecast household vehicle ownership and mileage by type of vehicle over time. The components of the simulator are developed in this research effort using detailed revealed and stated preference data on household vehicle fleet composition, utilization, and planned transactions collected for a large sample of households in California. Results of the model development effort show that the simulator holds promise as a tool for simulating vehicular choice processes in the context of activity-based travel microsimulation model systems.

In this report we present an analysis of the potential for reduced vehicle ownership within households based on sharing of completely self-driving vehicles that employ a "return-to-home" mode, acting as a form of shared family or household vehicle. An examination of the latest U.S. National Household Travel Survey (NHTS) data shows a general lack of trip overlap between drivers within a majority of households, opening up the possibility for a significant reduction in average vehicle ownership per household based on vehicle sharing. This reduction in ownership and an accompanying shift to vehicle sharing within each household, in the most extreme hypothetical scenario, could reduce average ownership rates by 43%, from 2.1 to 1.2 vehicles per household. Conversely, this shift would result in a 75% increase in individual vehicle usage, from 11,661 to 20,406 annual miles per vehicle. (This increase in mileage does not include the additional miles that would be generated during each "return-to-home" trip.) However, given the number of current unknowns regarding sufficient gaps between trips, future self-driving-vehicle implementation, self-driving-vehicle acceptance, and possible vehicle-sharing strategies within households, these results serve only as an upper-bound approximation of the potential for household sharing of completely self-driving vehicles.