A system of powering hybrid trucks through overhead wires is being tested at Long Beach, Califormia.
The basis of the "eHighway", developed by Siemens, is a series of overhead wires that would be installed over at least one lane of a highway, similar to the electrical wires of tram lines. Specially equipped hybrid trucks would connect to these wires via pantographs on their roofs. When connected, the truck runs exclusively on electrical power, switching to diesel when disconnected for passing, swerving, exiting and so on. When the truck brakes, energy can be fed back into the grid for use by other connected vehicles.
