Improvements will take place across the country

Work will take place in the north Thames, south Thames, the Midlands, Glasgow and south Wales areas.

Network Rail says the three-year scheme will form part of a long-term �2bn plan to overhaul signalling.

The government and rail regulator have yet to approve Network Rail's �2bn programme which would be spread across the next five to eight years.

Other track upgrades will also be carried out while the work to improve signalling takes place.

Passenger boost

NR's major projects and investments' director Simon Kirby said: "This is great news for millions of passengers who will find their journeys significantly improved.

"Investment on this scale will reduce delays by improving the reliability of the railway. This will mean long-term benefits from a better rail network for different regions across the country."

Network Rail said the deal involved making long-term commitments to suppliers which gave them the chance to invest in developing technology.

It also said the scheme gave Network Rail long-term cost guarantees, which would help it achieve cost targets.