The UK Government has confirmed plans to electrify the line from Cardiff to Swansea, as part of a UK-wide £9bn investment in the rail network.
The Ebbw Vale, Maesteg, Merthyr Tydfil and the Vale of Glamorgan lines will also be electrified.
The project, which will cost more than £600m, to be spend during the period 2014-2019.
– Secretary of State for Wales Cheryl Gillan MP
This investment sends out a clear message that Wales is open for business. Electrifying the rail line to Wales’ second city and to the South Wales Valleys will give people in these areas a chance to fulfil their potential by improving connectivity to labour markets and opening up prospects for jobs and investment.