The works in the North West of England will safely support more frequent services and the longer trains that are planned for the West Coast Mainline.
Work will start early this year and is expected to complete in 2016.
The ABC Electrification JV, which brings together global electrification experience, large scale rail capability and major programme management expertise, hopes to secure further work from Network Rail’s £9.4bn electrifying programme in future years.
Andrew Wyllie, chief executive of Costain, 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.”