The Siemens eHighway concept announced at the 26th Annual Electric Vehicle Symposium in Los Angeles recently is a two part system. The first involves the rollout of a two pole catenary system along one or more lanes on freight transport routes that caters for two-way electricity transmission and ensures a reliable power supply by feeding the overhead wire via container substations. The substations used in the current test project feature a medium-voltage DC switching system, a power transformer, a rectifier 12-diode array and a controlled inverter (for the feedback of the electric energy generated by regenerative braking).

Heavy goods vehicles have been fitted with a brand new pantograph - the second part of the concept - with an intelligent control system that can either automatically connect to an overhead wire upon detection by a built-in scanner or be manually controlled by the driver. Installed above the driver's cabin, the system is said to be capable of detecting the relative position of the overhead contact wire to the pantograph and counterbalances any lateral movements of the truck via active horizontal adjustment.

The test vehicles have also been retro-fitted with diesel-electric power trains, where they are always powered by an efficient electric motor but when in diesel mode, the vehicle's engine powers a generator, which in turn drives a downstream motor and turns the cardan shaft. When traveling under eHighway electric power, the vehicle is driven by the electric motor only. Siemens says that the driver is not aware of the transitions between different drive modes.