Other work includes track replacement disrupting services between Milton Keynes and Rugby, and rail replacement buses operating between Preston and Bolton due to a project to electrify the railway through Chorley.
Mark Carne, the chief executive of Network Rail, told the public accounts committee on Wednesday that the delayed project to electrify the London to Cardiff line would cost £2.5bn-£2.8bn £2.5bn-£2.8bne £874m projected instead.
Other work includes track replacement disrupting services between Milton Keynes and Rugby, and rail replacement buses operating between Preston and Bolton because of a project to electrify the railway through Chorley.
Hundreds of jobs will be created during construction on the Welsh phase of the £850m project to electrify the line between London and Swansea.
However Network Rail said the works had been planned in 2012, as part of the £650m project to electrify the line between Glasgow and Edinburgh, and said the 17 May operation could not be put off due to a range of technical reasons.
Perhaps the most ambitious project of all is to electrify Israel and create an oasis of electric cars in the Middle East.
Mr Hammond said: "We are now embarked on one of the biggest programmes of rail investment for 100 years, delivering more than 2,700 new rail carriages, a £900 million programme to electrify more lines and the vital Crossrail and Thameslink projects in London.
She met staff who have been involved in the project, unveiled a plaque to mark the occasion, and also named the engineering train set to electrify the railway from London to Swansea.
In "Empires of Light: Edison, Tesla, Westinghouse and the Race to Electrify the World," published this month by Random House, the author Jill Jonnes describes Edison's ambitious project.
Aided by an Export-Import Bank loan, Weldy-Lamont has taken a five-year electrification project in Ghana where, Mr. Hennelly said, "we're putting in the wooden poles and stringing the wires to electrify villages across the whole country".
