An investigation has been prompted by the train crash at Winsford in Cheshire two weeks ago, when 31 people were injured in a collision between a Pacer commuter train and a high speed inter-city train.

The railway inspectors say lightweight rail-bus trains do not meet current safety standards and they are concerned that some of them are now being used on the same tracks as conventional heavyweight inter-city and freight trains.

More exposed to collision

Deputy chief inspector Bob Smallwood said: "Clearly, Pacers were not built to current crash-worthiness standards and they don't behave as well as more modern rolling stock.

"What we're particularly looking at is whether or not the pattern of usage on the network has changed and they are more exposed to the type of collision that happened at Winsford or to collision with heavy freight trains."

Virtually demolished

At Winsford, one carriage of the rail-bus train was virtually demolished while the inter-city express suffered only light damage.

The inspectors say they will be looking at whether rail-bus trains should be more strictly segregated from conventional trains and whether any safety modifications can be made.

It was the first time that a lightweight train had been involved in an accident with a conventional heavyweight train.

Pacers were built in the 1980s as a cheap branch line train by bolting a bus body onto a freight line chassis.

Defended

Brian Curtis, South Wales and west of England divisional officer for the Rail Maritime Transport (RMT) union defended their safety record.

"For the last 15 years they have not been involved in any serious accidents."

"Obviously there are concerns, but you have to put it into perspective.