The prototype for the fleet of 82 Desiro HC electric multiple-units which Siemens is to supply for Rhein-Ruhr-Express services was unveiled at the Wildenrath test centre on July. Seven pre-series EMUs are to undergo extensive testing ahead of entry into passenger service at the end of 2018.

The Rheinland, Westfalen-Lippe Rheinland-Pfalz Nord, Rhein-Ruhr and Nordhessen transport authorities placed the order for 82 four-car units in March 2015, in a €1·7bn deal which includes 32 years of maintenance at a purpose-build depot in Dortmund. Because of the high value of the order, the authorities separated the procurement of the fleet from the tendering of the three RRX operating contracts, two of which were won by National Express and one by Abellio.

Siemens developed a new variant of its Desiro family for the contract, with single-deck driving cars and two double-deck intermediate cars giving a total of 400 seats; the EMUs will usually operate in pairs. The air-conditioned interiors feature wi-fi and power sockets, folding tables and reading lights in first-class.

The 160 km/h EMUs will be in continuous communication with the depot, proving data to support predictive maintenance and allow potential faults to be rectified before they occur. A driver assistance system will provide advice on braking and acceleration to help optimise traffic flows on the busy Rhein-Ruhr network.