Hundreds of new railway carriages destined for the South may have to stand idle, because �1bn of track improvements have yet to be carried out.

South West Trains' (SWT) new fleet of nearly 785 carriages will start arriving next week for testing.

The first train is to run in March 2003, but hundreds of miles of conductor rail and six electricity sub stations are needed before the full fleet can operate.

The work has yet to be approved.

Problem known

The government had planned to phase out old slam-door trains in the region by 2004.

Industry leaders say there is almost no chance of this happening now.

The new trains will offer massive improvements for customers

Jane Lee, SWT

The problem was known three years ago, but Railtrack did not make the improvements as it could not see how it would get the money back.

Even if a deal to do the work is signed soon, engineers say the very earliest it could start is next summer.

The problem is made worse for South West Trains as it will have to pay interest on loans for the new trains, even as they stand idle.

Action plan

This cost will almost certainly have to be met by the government.

The arrival of new fleet has been welcomed by South West Trains.

"This is good news - the new trains will offer massive improvements for customers", said spokeswoman Jane Lee.

"The Strategic Rail Authority and Railtrack have assured us that the work will be completed by 2004".

A spokesman for the Strategic Rail Authority said: "We are aware of the scale of the problem and we are getting together a plan of action to move towards getting a sufficient power supply."