Network Rail has named the firms that will carry out track renewals and enhancements over the next five years.
The organisation plans to renew 7,000 km of track between April 2014 and March 2019, at a cost of around £800 million. Babcock, Carillion and Colas have been selected to make the upgrades, carrying out the work over seven geographic lots.
Network Rail's track strategy is split into three work streams: plain line (conventional), switches and crossings, and plain line (high output).
When the current contract for the high output track renewal programme with AmeyColas expires at the end of this year, Network Rail will insource the work, saying this will create a less complex, more stable organisation.
Network Rail track programme director Steve Featherstone said: "By creating a single team within Network Rail we can make step changes in training and development in order to further improve safety and productivity within this key part of the industry."