The first vehicle of Southern’s 26 five-car class 377/6s has been completed at Bombardier’s Derby works.
Static testing of the first train is due to commence in February, with the completed unit expected to leave Derby in the late spring or early summer.
Testing on the mainline is to take place around Kent.
Introduction into passenger service will allow class 456s to be cascaded to South West Trains after they have received a C6 overhaul.
All of the 130 vehicles are expected to enter traffic for the December 2013 timetable change.
On November 14, Southern announced that it was exercising the option, which was due to expire on December 31, to order 40 more (eight five-car sets) Electrostar vehicles from Bombardier. These will be delivered in 2014 and unlike the 377/6 will be dual voltage.
The new suburban 377/6s were ordered because the 23 377/5s, and three of its own 377/2s, currently subleased to First Capital Connect, are not due to be returned to Southern before 2015 as originally planned due to delays in procuring the new Thameslink stock.
All of the 34 new units are being funded by Porterbrook.
The contract for the first 26 trains is worth £188.8 million and for the other eight around £34 million.