Each set is formed of a 69.60 Mobile Maintenance Unit (MMU), a 69.45 intermediate vehicle, and a 69.40 Traction and Supply Unit (TSU).

The trains will be used primarily to replace turnout closure rails (up to 13.72m in length), rail pads, and fishplates as well as maintenance and inspection of switches and crossings.

The intermediate vehicle has a loading capacity of 38m2/20 tonnes for carrying materials and equipment to the worksite. The TSU has a workshop area, together with a mess room and kitchen. All maintenance and repair work on track and switches is carried out in the 68m-long MMU, which is equipped with hydraulically-adjustable side walls. These can be extended laterally to increase the workspace by up to 600mm on either side of the vehicle.

Materials can be moved between units using a crane with a lifting force of 2 tonnes per module.