Southern has launched a procurement competition for 116 electric vehicles with an option for a further 140.
The trains could be used on Thameslink routes before being cascaded to newly-electrified HLOS routes as new Siemens rolling stock is introduced.
In today’s announcement, Southern also confirmed an order for 40 more Electrostar vehicles from Bombardier.
The 40 dual-voltage carriages are an extension of the 130 carriage order won by the rolling stock manufacturer at the end of last year.
The first vehicle of Southern’s 26 five-car class 377/6s has now been completed at Bombardier’s Derby works.
Chris Burchell, managing director of Southern, said: “We are delighted to be able to order these additional vehicles which will provide much needed capacity on our network.
“We are also pleased that we are in a position to assist the Department for Transport in facilitating the cascade of electric vehicles as featured in the High Level Output Statement.”
Rolling stock for the new competition will be dual voltage four-carriage sets.
Transport Secretary Patrick McLoughlin said: “Our support for Southern will not only boost capacity but help secure British jobs. The deal for the 40 new carriages, helped along by my department, demonstrates the government’s ongoing commitment to invest in Britain’s railways.
“My officials are working with Southern to accelerate their procurement process for up to 256 carriages because our ambitious electrification plans requires additional rolling stock on the network.”
