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If AV fleets become widely available, what happens to vehicle ownership? Will changes be universal, or will they be regional?
What is driving change?
Transportation network company (TNC) user surveys suggest that a primary motivator for users to hail a ride is to avoid expensive or scarce parking. Because researchers to date have studied TNCs as a harbinger of a new era of car access and extrapolate those findings to autonomous vehicles (AVs), we could see a significant reduction in parking demand in the future.
Autonomous vehicles (AVs) may increase or decrease total vehicle miles traveled (VMT) in the future, although most researchers predict the former, citing research on the impacts of transportation network companies (TNCs) on VMT. VMT may also rise if, for example, AVs circle blocks continuously waiting to pick up their passenger rather than parking.
Several studies examining the impacts of transportation network companies (TNCs) on congestion have concluded that TNCs are contributing to increased congestion. On the one hand, autonomous vehicles (AVs) could contribute to increased congestion resulting from a combination of induced and latent demand, mode replacement, and increased circulation (e.g., continuously circling the block when waiting to pick up a passenger rater than parking). On the other hand, the potential exists for AVs to help decrease congestion if they are able to travel in closer proximity than human-driven vehicles, resulting shorter headways and narrower travel lanes.
The growth of transportation network companies (TNCs) in the past several years has impacted travel behavior, with preliminary research suggesting that TNCs are among the factors impacting transit ridership. If AVs lower travel costs, potential modal shifts may occur depending on trip distance and purpose.
What Could Happen?
- Personal vehicle ownership could diminish substantially as mobility as a service becomes the new dominant paradigm. If new mobility and Mobility as a Service (MaaS) can provide options that are more convenient and less costly than vehicle ownership, it is possible that the number of vehicles owned by a family could decrease and the number of completely car-free households could rise. While more likely to take place in urban environments, this paradigm shift could also impact suburban areas and eventually rural areas.
- Conversely, personal vehicle ownership might remain commonplace, if not dominant. Vehicle ownership could continue to be the dominant paradigm, or it could persist in a lesser form alongside mobility as a service option. This is more likely in less dense, rural areas or areas where urban sprawl is increasing rather than decreasing. Even in situations where new mobility and MaaS options are more convenient or affordable, other factors such as cultural or societal expectations could prolong or indefinitely ensure the usage of personal vehicles in any location, including highly dense urban areas with comparatively low vehicle miles travelled averages.
- Or vehicles might be owned with others, in fleets instead of individually. Co-ownership of AVs could become commonplace, with multiple individuals each paying a portion of the purchase and maintenance costs of vehicles that they share the use of. This could permit the co-owners transportation flexibility to a degree potentially not offered by fleet-based AV networks as well as the benefits of the limited parking needs of a shared vehicle, while also still allowing them to use mobility as a service options for day-to-day commuting purposes.
EVIDENCE TO DATE
- Vehicle ownership has increased faster than population growth in most major US cities, regardless of new mobility. Even in areas where new mobility options have flourished and are widely used, per household vehicle ownership is continuing to increase. While this may be partly due to a thriving economy that makes automobile purchase more attainable, it mutes new mobility claims of complete paradigm shifts, even in larger and dense cities.
- However, increases in new mobility may have already led to more car-free and car-light households in some cities. Cities such as Seattle, San Francisco, Boston, Philadelphia, and Chicago have all seen increases in the number of car-free or car-light households, and all have seen this outpace population growth. Seattle leads this trend with a more than 22% increase in car-free and car-light households between 2012 and 2017.
- Additionally, vehicle registration rates seem to drop after Uber and Lyft arrive in a state. A regression analysis looking at impacts after Uber and Lyft arrived in a state shows an average of a 3% decrease in vehicle registration rates. If this holds true, it could eventually significantly reduce the overall number of vehicles operating in states.
- According to one study, energy use and emissions in a future combining shared mobility with AVs could range between -60% and +200% of current rates.
- While TNCs may potentially decrease vehicle ownership rates, they aren’t helping congestion: 49% to 61% of ridehailing trips correspond with increased VMT.
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