How much carbon dioxide can car-sharing slash?

Car-sharing is quickly gaining popularity in cities around the world. Proponents say that it’s a green way to get around town. In a report published in July, researchers calculated car-sharing’s precise impact by analyzing the car-share service car2go in five North American cities. Each car2go eliminated up to 11 privately-owned vehicles from the roads and prevented 10 to 14 metric tons of carbon dioxide emissions per year, they found.

The first-of-its-kind study, undertaken by engineers at the University of Berkeley’s Transportation Sustainability Research Center (TSRC), was co-sponsored by car2go and the U.S. Department of Transportation. Car2go operates in 9 countries and 30 cities and is the biggest car-sharing service in the world at present. While Zipcar offers multiple car models and a service model in which cars need to be returned to specific parking spots, car2go owns a fleet of tiny two-seater Smart cars that users can pick up and drop off at different spots within a “home” zone.

The Berkeley researchers gathered car-sharing data from around 9,500 car2go members in Calgary, San Diego, Seattle, Vancouver, and Washington, DC over three years. They surveyed members about their driving habits—both with privately owned and car2go vehicles—and about whether they had gotten rid of their own vehicle or not bought a car because of access to car2go. They also gathered vehicle activity data to evaluate the total distance that car2go vehicles travel in a city during a year.

The impact of even small behavior changes was pretty big, the researchers found. For every car2go vehicle on the road, members sold somewhere between one and three personal vehicles and avoided buying between four and nine vehicles. Each shared car2go vehicle removed as many as 11 personal cars from the road, adding up to 28,000 cars across five cities.

Based on the driving responses from the survey, the researchers calculated that people traveled 6­ to 12 million fewer miles a year across the five cities. And that was a conservative number. The driving miles saved could be as much as 21 to 37 million. This more liberal estimate would amount to saving 5,300 to 10,000 metric tons of carbon emissions per year.

Another positive side-effect of car-sharing? Less traffic and parking congestion, car2go North America CEO Paul DeLong said in a press release.

One slight downside was that some users reduced their public transit use due to car2go. But as TSRC co-director Susan Shaheen, who led the study, told CityLab, services like car2go could also act as a way to connect more people lower-density areas outside urban centers to public transit. —Prachi Patel | 11 August 2016

Source: Elliot Martin and Susan Shaheen. Impacts of car2go on vehicle ownership, modal shift, vehicle miles traveled, and greenhouse gas emissions. 2016.

Image: GriinBlog via Flickr

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