The 650V dc bidirectional vehicles will be 43m long and 1.3m wide, and will accommodate up to 250 passengers, 82 of them seated.

The first six vehicles will be delivered in 2015 for the opening of the extension to the city's exhibition centre, while the remainder will enter service in 2017, when the line to Rotteckring is due to be completed.

VAG has not disclosed the purchase price for the vehicles, although it says the value of the contract is "less than €40m."