First Advisor

Kelly Clifton

Term of Graduation

Spring 2019

Date of Publication

Winter 3-19-2019

Document Type


Degree Name

Master of Science (M.S.) in Civil & Environmental Engineering


Civil and Environmental Engineering




Automobile ownership -- Oregon -- Portland -- Case studies, Apartment houses -- Oregon -- Portland -- Case studies, Car sharing, Ridesharing, Bicycle sharing programs, Automobile parking, Local transit passes, Transportation demand management



Physical Description

1 online resource (viii, 125 pages)


Since the beginning of the 21st Century, the world has seen the rapid development of the so-called "sharing economy" or collaborative consumption (Botsman, 2010). One of the first areas affected by the shared economy is vehicle ownership. With the emergence of several new providers of mobility services, such as Uber and car2go, there has been the promise of changes to the traditional way of owning and using a vehicle (Wong, Hensher, & Mulley, 2017). One potential consequence of shared mobility services is the reduction in vehicle ownership. At the same time, cities are trying to anticipate these changes by reducing the amount of space dedicated to parking, including parking requirements for residential developments.

This thesis aims to assess the extent to which new shared mobility services (specifically, carsharing, bikesharing, and ridehailing) and travel demand management strategies (especially parking requirements and transit pass availability) relate to vehicle ownership among residents of multifamily dwellings. To do this, we use a web-based survey targeted to residents of multifamily apartments from Portland, Oregon. With these data, we built a multinomial logistic of the number of the vehicles owned as a function of socio-demographics, built environment, parking supply, transit passes, and three forms of shared mobility services.

Results suggest that there is a strong association between shared mobility use and car ownership. However, it is not as significant as the effects of income, household size, distance to work, transit pass ownership, or even parking availability. Carshare use was negatively associated with the number of household vehicles, suggesting that it may be a useful tool in reducing car ownership. For respondents with higher education and income levels, increased carshare use was associated with fewer cars. Ridehail use, however, was not as clearly associated with reducing vehicle ownership and the effect was much smaller than that of carsharing. Parking availability in the building also has a significant and positive association with vehicle ownership. In sites with no parking available, there is an increased chance of the household owning less than two or more vehicles. However, this effect seems to disappear with the increased use of shared mobility. For all income levels, monthly use of ridehail and carshare between two and three times may decrease the odds of owning two or more vehicles.

The use of both options, relaxing parking requirements and shared mobility availability, seems the best strategy to reduce vehicle ownership. In the short term, it is an alternative to those residents that decide to get rid of one or all cars but still are not ready to give up using cars. For the long term, a new relationship with vehicle ownership can be built now for the younger generation.


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