.

Charles J. Murray, Senior Technical Editor, Electronics & Test 6/2/2011    Roadway barriers, the last line of defense for hundreds of military installations and utility plants, are undergoing a transformation. Once powered exclusively by hydraulics, the giant barriers are now moving to simpler, greener electric actuators.   For roadway barriers, that's a big change. Designed to stop a 15,000-lb truck traveling at 50 mph, the beefy barriers have traditionally employed hydraulics as a means of quickly raising 6,000 lb of steel into the path of a truck. "The idea was always to be able to stop the biggest, baddest truck you could find," says Paul Roland, director of engineering at the  American Physical Security Group (American PSG) , a maker of roadway barriers. "They have to stop the truck with zero penetration and still be operable afterward." Doing so with a servo motor and a ball screw, however, is a comparatively new idea. For more than a...