Bombardier was awarded an SKr 5bn ($US 600m) contract in May 2013 to supply an initial batch of 96 C30 cars with an option for up to 80 additional vehicles.

The C30s are the first metro trains in Sweden to be equipped with air-conditioning and each 70m-long two-car train will accommodate up to 635 passengers, 140 of them seated.

The first C30s will enter service on the Red Line in 2017, replacing CX trains, which date from the 1970s.

With the completion of resignalling and the delivery of new trains, peak capacity on the Red Line will be increased from 24 to 30 trains per hour by 2021.

The C30 fleet will initially operate with drivers but the trains are equipped for the eventual rollout of full Unattended Train Operation (UTO) on the Red Line.