Motorists in Roanoke, Virginia, got the chance to test a novel kinetic energy recovery device just by driving over a speed bump.

As part of a real-world test of its MotionPower Express system, New Energy Technology installed an energy-recovering speed bump at the entrance to the busy Roanoke Civic Center during the weekend Roanoke hosted a gun show and circus. As cars crossed the speed bump, their tires depressed treadles that captured kinetic energy, which was converted into electricity.

The company calls it a “rumble strip,” since it’s not as tall as the bright yellow behemoths dotting subdivisions and school zones. Whatever you call it, drivers who traversed the devices generated enough energy to power an electronic sign. Without the rumble strip, that energy would’ve been wasted as brake heat.

New Energy estimates an event like that held in Roanoke, where 580 cars passed over the rumble strip in six hours, could power a 150-square-foot electronic billboard or marquee for one day. In addition to lighting up temporary signs at special events — think, “Game day parking: $65? or “Lot Full” — the technology is ideal for powering informative signs in construction zones where traffic should be slowing down anyway.

Sainsbury’s, the self-proclaimed eco-conscious superstore that dots the United Kingdom, installed “kinetic road plates” in the car park of a store in Gloucester in 2009. The company says the plates generate enough power to run the store’s cash registers.

New Energy says there’s also room for permanent installations, powering lights and signs at tollbooths, rest areas, airport arrival and departure lanes and parking lots. Two years ago, MotionPower even demonstrated one of their speed bumps at a Burger King drive through in New Jersey, helping power the fast food outpost.

It sounds ideal: Americans can go about their daily activities, driving to gun shows and circuses, powering the traffic infrastructure of the cities they’re traveling through. The city of Roanoke agreed.

“New Energy can offset the city’s cost of operating traffic control devices, such as traffic signals and street lights,” said Mark Jamison, Roanoke’s Transportation manager. “This innovative partnership with New Energy Technologies has the potential to provide a more sustainable environment, while simultaneously conserving strained budgets of cities across the nation.”

New Energy is keeping quiet on how much energy the speed bumps create and how much it costs to install them. However, the City of Roanoke will be publishing results of the trial installation in January, which may shed some more light on how much money MotionPower might save municipalities.

UPDATED 1:46 p.m. EST to address the cost issue.

Photos: New Energy Technologies