A joint venture between Balfour Beatty and Tarmac's rail arm has been picked as preferred bidder for a £200m upgrade of overhead lines on the West Coast Main Line.

The work will be part of Railtrack's £2.2bn modernisation of the line that will allow trains to run at up to 140 mph from 2005.

The plan is to slash journey times between London, the Midlands, North-west and Scotland.

GTRM, a joint venture between Tarmac and Alstom, was for some time considered a favourite for the upgrade as it already held the maintenance contract for the line.