The project is part of a £300m investment by Network Rail in power upgrade and a wider £9.4bn investment in electrifying British railways.
The works in the northwest of England will allow the introduction of more frequent services and the longer trains that are planned for the West Coast Mainline.
Work starts in early 2013 and is expected to complete in 2016.
Costain chief executive Andrew Wyllie said: "The award of this contract provides further demonstration of Costain's position as a major player in the rail sector, delivering integrated services for complex and large scale infrastructure projects which are vital to the UK economy."
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