The £20m dive-under is needed so that trains leaving the Acton freight yard do not delay passenger trains heading towards Acton Main Line and on to central London.
Freight trains currently enter and leave the freight yard by crossing the mainline passenger tracks. The new dive-under will allow the trains to access the yard without affecting passenger services, thus increasing capacity and reliability.
The start of excavation follows nearly two years of work to re-configure the freight yard. The work on the dive-under is being managed by Network Rail and is expected to last until 2016.
Network Rail programme director for Crossrail, Rob McIntosh, said: “The Acton dive-under is one of the most complex infrastructure structures we are delivering for Crossrail. The new dive-under will ensure the activities of this important freight yard, which services the London network, are secured when the Crossrail services begin. The team has worked closely with principal contractors BAM Nuttall to achieve this milestone and over the coming months we will really be able to see the dive-under structure emerge.”
Network Rail is responsible for the design, development and delivery of the parts of Crossrail that are on the existing network. The work includes upgrading 43 miles of track as well as improving 27 stations from Maidenhead in the west to Abbey Wood and Shenfield in the east.