The electrification of the Valleys railway lines will be completed by 2019 according to the UK Transport Minister, Simon Burns MP.
The project's cost is an estimated 350 million pounds with work due to start in 2015.
During Transport Questions in the Commons the Minister said it would be "a significant boost" to South Wales, which "will create tremendous opportunities for business travel and passenger travel".
The scheme is part of a modernisation which includes the 1 billion pounds electrification of the line between Swansea and London.
More top news
A calm and quiet night ahead, but inland temperatures could drop enough for some grass frost by the early hours.
Education reporter Megan Boot explains issues facing the education system ahead of the 2016 Assembly election.
An exclusive poll for ITV Wales shows support for the Conservatives and UKIP is up, whilst Labour's support remains unchanged.