Costs for electrifying the Great Western line connecting major towns and cities across southern England and South Wales have increased by half a billion pounds, according to Shadow Transport Secretary Mary Creagh.
During a hearing in the House of Commons, Creagh urged Transport Secretary Patrick McLoughlin to confirm that the budget for the project has increased from the previously approved £1.1bn to £1.6bn.
"In April, when I asked you about problems with the electrification of the Great Western main line, you said 'There will always be problems'.” Creagh said.
"Can you confirm the Great Western £1.1bn electrification project is now a £1.6bn electrification project and can you see which electrification projects will be delayed or cancelled when your department has concluded its panic review of your flagship projects?"
McLoughlin downplayed the concerns, saying he was “working with Network Rail … to make sure we get the electrification programme delivered, and delivered within the overall budget."
The electrification of the Great Western main line, to be completed by 2017, will see diesel-powered locomotives replaced with greener electric trains on routes between London and Bristol, including Newbury and Oxford, and the route to Cardiff.
Electric trains emit around 20-35 per cent less carbon than diesel-powered locomotives and don't produce any emissions during the actual operation, improving air quality in pollution hot spots such as city centres and main line stations.
Electric trains are also considerably quieter, reducing unwanted noise pollution which is a nuisance to the public.
Great Western said it is carrying out most of the work during night hours to minimise disruption of services.