New S Stock Tube trains have started service on the Circle line, nine months after the first of 53 new vehicles was delivered to the Hammersmith & City line.
The Circle line is the latest Underground route to receive the trains. Last year, a roll out of 58 trains was completed on the Metropolitan line and the first of 53 new trains arrived on the Hammersmith & City line.
The S Stock order is worth around £1.5 billion and will see 191 new trains arrive on the network by the end of 2016.
The air-conditioned seven-car trains will generate 17 per cent extra capacity on lines previously served by stuffy six-car units.
Phil Hufton, London Underground’s chief operating officer, said: “As part of our continued drive to improve our passengers’ experience of travelling on the Tube we’re delighted to be rolling out these new air-conditioned, high-specification trains.”
Next year, 80 S Stock trains, the only walk-through trains on the network, will be delivered to the District line.