The eight-axle articulated LRVs were built by Duewag between 1986 and 1994, but were extended to 33m through the addition of a low-floor section in 1996. The oldest vehicles in the fleet have completed 2 million km in service.

The refurbishment work will involve a complete renewal of the mechanical parts of the vehicles with the objective of guaranteeing operation until 2024. There is also an option to replace windows which have been damaged by graffiti.