The South West has seen serious rail disruption over Thursday night and Friday morning.

Hundreds of passengers suffered long delays because of a signal failure on the main line into the region on Thursday night.

The Great Western main line from Paddington to Penzance was brought to a halt for two hours when computer failure at Slough caused a complete signal blackout.

Also, Cornwall's main line trains were stopped by a lorry hitting a bridge at St Austell on Friday.

The line at Dawlish goes along the sea front

After the signal failure, more than 100 trains were delayed, with passengers diverting via Waterloo to try to reach South West destinations.

Railtrack has said the problem was a rare one and has apologised.

First Great Western described it as major chaos.

All mainline services into Cornwall by First Great Western, Virgin and Wessex were halted temporarily while the St Austell bridge, which had been hit, was checked.

Meanwhile, Virgin's new Voyager trains are still susceptible to salt water on the main line through Devon at Dawlish.

The tracks go along the sea front and tides can result in salt water being thrown over lines, causing electrical systems in the new trains to short circuit.

High tides

Virgin said, in general, the Voyagers have not had to be stopped recently.

The company said the problem only occurs when there are high tides with heavy seas and contingency plans were in place if conditions got bad.

The company also said its investigation into the problem will go on for the next eight weeks.

Engineers are determining what modifications can be made to prevent the problem occurring again.

The modifications will then be carried out during the trains' regular maintenance.