Works, which are part of the Crossrail programme, include plain line track renewals, installation of new switches and crossings, associated switch operating mechanisms and modification to the overhead line system on the main line.

These advanced works will be completed by early 2013, with the remaining programme of work for Acton, including a diveunder, due for completion in 2016.

Acton freight yard is a significant part of the network but to enter and leave the yard, trains currently need to cross main line passenger tracks.

The plans for these modifications to the yard and a new diveunder, which is currently out for tender, will enable freight trains to leave the yard without affecting passenger trains and provide increased capacity for freight.

Jorge Mendonca, Crossrail programme director, Network Rail, said: “The work at Acton is an important step in delivering a more reliable service for passengers while providing more capacity in the Paddington approaches area.”

Stuart Birch, major projects director for VolkerRail, said: “This is a great opportunity for us to work together with our sister company VolkerFitzpatrick to demonstrate our complementary capabilities and experiences.”

Network Rail is responsible for the design, development and delivery of the parts of Crossrail that are on the existing network, covering 43 miles of track and 28 stations from Maidenhead in the west to Abbey Wood and Shenfield in the east.