Rail electrification: Driver's eye view for Crabb
Welsh Secretary Stephen Crabb has said the UK government is "absolutely committed" to electrifying the main rail line between London and Swansea.
He said he had an "unmissable view" of the effects of the upgrade so far from the driver's cab of the 0815 from Paddington to Cardiff on Thursday.
Mr Crabb said the route was a "vital link" between Wales and the capital.
In June, Transport Secretary Patrick McLouglin said the Great Western line remained "a top priority" in Network Rail's upgrading programme, despite concerns about delays and rising costs.