Germany-based Siemens AG, a leading global technology firm, has been experimenting with a specialized stretch of highway equipped with overhead power lines and specially equipped diesel-electric trucks to determine if it is possible to power them in electric mode while on the move. The project has reached the point that larger tests are under way in the German State of Hesse.

The Siemens system uses specially equipped Class 8 European tractors with diesel-electric powertrains. But unlike most hybrid trucks, these are fitted with an extendable pantograph on top of the truck cab. A pantograph is the fork-shaped electrical conduit commonly seen on trams, streetcars, and light railcars that physically connects an electrically powered vehicle with the overhead power lines that provide electricity.

Under the Siemens experimental system, these trucks can operate normally under diesel power in areas where no overhead lines are available. But, on specially built roads with dedicated electric truck lanes, the driver can extend the pantograph, making contact with the high voltage power lines overhead. Once contact is secured, the truck’s diesel engine goes to idle and the electric drive system propels the vehicle down the road at normal highway speeds.

The system was initially tested on closed track conditions in Germany, Sweden and California. Now, the first test route for overhead-line hybrid trucks (OH trucks) has been inaugurated on the A5 autobahn in Hesse in real-world driving conditions. Plans call for five OH trucks to be running regularly on the route between Weiterstadt and Langen/Mörfelden by the middle of next year.

Germany’s Federal Ministry for the Environment has funded construction of the pilot project with 14.6 million euros ($16.4 million). A further 15.3 million euros ($17.2 million) available for conducting the field trials in Hesse that will run until the end of 2022. The Hessian road authority is coordinating the project and is responsible for the operation of the eHighway. The Technical University Darmstadt, Siemens Mobility GmbH, and ENTEGA AG are also participating in the project.

“Electrified overhead line trucks are a particularly efficient solution on the way to climate-neutral freight transport,” said Rita Schwarzelühr-Sutter, parliamentary state secretary of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. “We’ve tested the system for many years on private test routes. We’re now inaugurating practical tests on the A5 autobahn between Frankfurt and Darmstadt, and two further test stretches will follow in the States of Schleswig-Holstein and BadenWürttemberg.”

“The inauguration of Germany’s first eHighway in Hesse marks a milestone in the de-carbonization of road freight transport in the country," said Roland Edel, Chief Technology Officer of Siemens Mobility GmbH. “The Siemens Mobility innovation combines the advantages of electrified rail lines with the flexibility of road freight transport, thus offering an efficient, economical and environmentally compatible alternative to truck transport with combustion engines,”

As the project progresses, ENTEGA will work out energy-related and legal planning issues and develop a billing system concept for fleets. Other research will evaluate the system from the point of view of power utilities and for all issues related to energy laws and regulatory matters.