Carnegie Mellon University
November 11, 2013

Press Release: Carnegie Mellon Researchers Find Limited Residential Parking a Barrier to Electric Vehicle Adoption

Contact: Chriss Swaney / 412-268-5776 /

Electric VehiclePITTSBURGH—Will electric vehicles replace gasoline vehicles? Not with our current parking infrastructure, say Carnegie Mellon researchers.

Elizabeth Traut, a mechanical engineering doctoral student, Jeremy Michalek, a professor of mechanical engineering and public policy, and Chris Hendrickson, a professor of civil and environmental engineering and public policy, analyzed parking and charging availability for electric vehicles in the U.S.

"The discussion of electric vehicle (EV) charging has focused on public-use chargers, but most EV charging will be done at home. And most car-buyers will expect to have reliable daily access to a charger before investing in an EV," Hendrickson said.

EVs include battery electric vehicles, which run on electricity instead of gasoline, and plug-in hybrid electric vehicles, which use a mix of gasoline and electricity.

The good news is that today's infrastructure can already support some EV adoption.

"About 40 percent of U.S. households have an existing electrical outlet near a parking space suitable for charging a low-range plug-in hybrid electric vehicle overnight," Michalek said, "but many households own multiple vehicles — often without enough garage or off-street parking for all of their vehicles."

The bad news is that charging potential is limited by parking availability.

"On the whole, less than half of U.S. vehicles have dedicated off-street parking at an owned residence in a location suitable for installing a charger," Michalek said. "That means if we want more than half of the vehicles on the road to be electric, we're going to need major changes in residential parking - and that doesn't happen quickly."

The study, which was funded in part by grants from the National Science Foundation, CMU's Steinbrenner Institute for Environmental Education and Research, General Motors, Ford and Toyota, is to appear in the journal Transportation Research (Part D).

The study comes as vehicle manufacturers are introducing new EVs for sale and federal and state governments are offering incentives for purchasing EVs. States like California also have introduced mandates that effectively force most automakers to sell EVs.

"Analysts have ignored the barrier that parking may present to electric vehicle adoption," Traut said. "We've seen studies that predict EV adoption as high as 80 percent by 2030. But to sell that many EVs we would not only need to make them less costly and more attractive to consumers — we would also need to address parking."

"Even if everyone wanted and was willing to pay for EVs, we couldn't convert the whole fleet without major infrastructure changes," Traut added. "Landlords have little incentive to invest in chargers that only some of their tenants may use, and homeowners simply don't have enough dedicated parking spaces to charge all of their vehicles."

"The bottom line, is that we are ready for many households to adopt some EVs now, but we should not expect EVs to dominate the market any time soon," Hendrickson said. "They will more likely be part of a diverse transportation strategy in the future. If we want EVs to be a larger part of our future transportation solution, we need to be thinking now about parking and charging availability. Incentivizing landlords, where appropriate, and designing adequate parking and charging capability in new construction would be a start."


CMU Professor Chris Hendrickson says most electric vehicle (EV) charging will be done at home. And most car-buyers will expect to have reliable daily access to a charger before investing in an EV.