How car sharing and ride sharing can help transportation agencies

By Chris McCahill

The primary focus of transportation agencies for many years has been to keep pace with ever-rising levels of traffic. New policy goals focused on health and environmental impacts in California, Massachusetts, and elsewhere, as well as nationwide trends in travel behavior have begun to change this focus. The total vehicle miles traveled in the U.S. have leveled off since around 2007 due to a variety of factors outlined in the SSTI paper, VMT Inflection Point. Now, the emergent sharing economy also appears to be playing some part in markets that currently are isolated but that could grow quickly.

Professor Susan Shaheen and other researchers at UC-Berkeley have studied the influence of car sharing (short-term, membership-based car rentals such as ZipCar) for nearly two decades. In a recent article for the San Francisco Bay Guardian, Shaheen explains some of what we now know about their influence. To begin with, she points to her 2010 study showing that each shared car takes about nine to 13 private vehicles off the road, cutting down dramatically on parking needs and vehicle ownership costs.

Perhaps more valuable to transportation agencies, however, is a 2007 study by Professor Robert Cervero that looks at the influence car sharing can have on VMT. Cervero studied the travel behavior of car-share members and nonmembers in San Francisco for a period of four years after the program’s launch. After adjusting for travel mode and vehicle occupancy, he found that VMT decreased by 67% for a typical car-share member during the study period—an effect he attributes to mode shifts and shorter trips. He explains, “Car-share membership instills a resourcefulness in travel habits, whether in the form of multiple-occupant car-share travel or taking transit, walking, or cycling when not driving car-share vehicles.” In other words, the option of car sharing provides an opportunity for households to transition to car-free or low car-use lifestyles, which many do.

If that’s true for car sharing, though, then could ride-sharing programs like Lyft and Uber have a similar effect? A recent New York Times article, in which Sheehan and others weigh in, suggests that it could. Among the article’s more noteworthy claims is that these programs could ultimately help cut VMT and reduce the overall traffic load in urban areas. The experts in the article suggest that, like car sharing, ride-sharing programs complement walking, biking, and public transit, making them more attractive and viable alternatives to private automobiles. Unlike most taxis, however, which are often heavily regulated, ride-sharing services can also innovate and expand in unexpected ways and potentially open up new markets on the urban fringes.

Chris McCahill is a Senior Associate at SSTI.