The 12.5 mile section includes all lines running between Stockley Junction near Heathrow Airport and Maidenhead on the Crossrail West outer section.
Balfour Beatty is already involved in the Crossrail programme. Its chief executive Andrew McNaughton said "we... very much look forward to continuing our long-term relationship with Network Rail and continued support with the Crossrail programme. Our investments in specialist High Output plant solutions for these works confirm our ongoing commitment to the UK rail market and, in particular to the National Electrification Programme."
Work commences this December and is due to be completed in late 2016.