Institute of Urban and Regional Development

One of the more innovative and potentially resourceful urban transportation initiatives in recent times is car-sharing, the sharing of motorized cars through cooperative arrangements. It's a market-based strategy that, proponents maintain, is suited to urban settings where parking is in short supply, where good public transit and easy walking access makes car ownership less imperative, and where the prospect of access to a diverse fleet of vehicles appeals to niche markets such as young professionals without children and political 'greens.'

In this report, the short-term travel-behavior impacts of car-sharing in the city of San Francisco are evaluated. San Francisco's program, City CarShare, was launched in early March 2001 and has steadily gained popularity as more and more people have voluntarily joined the program. For purposes of studying "before and after" changes in travel demand, data were compiled both prior to program implementation and 3-4 months into the program. To remove the influences of other factors that could explain changes in travel demand besides car-sharing itself, a controlled experimental framework was adopted which involved comparing changes in travel demand between City CarShare participants and an otherwise comparable group of non-participants over time. In addition to evaluating impacts, car-sharing is profiled in terms of trip purposes, travel durations, spatial patterns of trip-making, and other attributes.

Because the study shows overall impacts of car-sharing only 3-4 months into the program, the researchers note that firm inferences cannot yet be drawn, however, the results hint at some of the behavioral adjustments that might be tracked over time as the program matures and participants settle in to more permanent patterns of behavior.