Delivery of the trains has been delayed considerably by complications in the approval process. Alstom was forced to modify the braking system to meet Hungarian standards after type approval the National Transport Authority (NKH) refused to grant type approval, prompting BKV to cancel the contract in October 2010.

However, following amendments to the contract, the type authorisation process was restarted and the trains were approved after completing 35,000km of fault-free operation.

BKV has ordered 22 five-car Metropolis sets for Line 2, each with capacity for up to 209 seated passengers and 814 standees. The 100m-long sets are air-conditioned with full-width gangways. Traction equipment was manufactured in Hungary while the production of the car bodies and final assembly took place in Alstom's Katowice plant in Poland.

The first trains will enter revenue service on Line 2 at the beginning of September. Although Alstom says it already assembled all 22 metro trains, modification work is continuing which means it will be several months before the whole fleet enters service.

The Metropolis sets for Line 2 will replace 40-year-old trains built by Metrovagonmash, Russia, which will be withdrawn. Many of these vehicles have already been taken out of service due to cracks in the bogie frames and BKV is struggling to keep the remainder of the fleet in service.