Workhorse locomotives travel 1,000 miles a day

The train

In the industry, the Alstom Class 91 locomotive and carriages are known as reliable workhorses. They are capable of speeds of up to 140mph, although the train that derailed yesterday was travelling only at an estimated 110mph.

In the industry, the Alstom Class 91 locomotive and carriages are known as reliable workhorses. They are capable of speeds of up to 140mph, although the train that derailed yesterday was travelling only at an estimated 110mph.

In all, 31 locomotives and 303 coaches were built by GEC Electric Metro-Cammell (now owned by Alstom) between 1987 and 1990. The first was brought into service in 1989 by GNER. Each piece of rolling stock cost between £700,000 and £1m, and would be expected to travel up to 1,000 miles every day at average speeds of 100mph for 30 years.

"These have always been considered one of the best fleets available in the UK," said a spokesman for Alstom yesterday. Her view was echoed by Pip Dunn of Rail magazine. "It's a very safe train," he said, "especially when you consider the mileage that they're putting in. They travel between London and Edinburgh or London and Glasgow via Newcastle, all on the East Coast line.

"They might start at 6am, travel 400 miles, turn around, travel back and then travel up again. They could be doing 1,000 miles a day, about twice as much as a commuter train, which will be travelling much more slowly, starting and stopping."

The Class 91 Intercity 225s cut journey times by using a dual system, in which a "steer car" at the other end of the train from the locomotive enables the train to be driven either from the front or from behind - eliminating the need to shunt the engine at the end of the journey. That too has made them popular with train companies.

"Both Virgin and GNER are bidding for the franchise to run the East Coast line, and there is some talk that they will buy new rolling stock," said Mr Dunn. "In that case I would expect the Class 91 to be snapped up by another train operator."

The trains have been involved in only one other derailment, in 1998, when metalfatigue in a wheel led to a crash. The incident, at Sandy, Bedfordshire, involved GNER's nine-coach King's Cross to Edinburgh service.

Because of the 1998 derailment, the company removed all Mark 4 coaches from service for wheel checking after discussions with Railtrack and the Health and Safety Executive.

Investigations found metal fatigue in the wheels of the rolling stock, which is operated only by GNER and which was introduced in 1989. A maintenance firm was fined £175,000 in July this year in response to the inquiry results.

The questions now will be whether the life expectancy of the Class 91 systems is somehow being reduced by high-speed vibrations that create micro-fractures in the wheels or axles, and so might lead to a repeat of yesterday's incident.

Once built, the rolling stock becomes the responsibility of GNER, which would also ultimately be in charge of checking for any deterioration in the wheels or axles.