Experts say they don't understand cause of accident

The Report

A dangerous but little-known form of metal fatigue is believed to have been a key factor in the Hatfield rail crash.

A dangerous but little-known form of metal fatigue is believed to have been a key factor in the Hatfield rail crash.

Presenting its interim report on the high-speed derailment, which killed four and injured 35 on Tuesday, the Health and Safety Executive (HSE) disclosed that the problem has been seen at several sites around the country, but "is yet to be fully understood".

Vic Coleman, the chief inspector of railways, said a specific form of track fatigue known as gauge corner cracking had been discovered immediately after the crash. The fatigue, which causes hairline fractures, has been found in other parts of Britain and on the Continent.

Mr Coleman said: "I think the rail industry itself does not have all the answers to this particular problem. Whether it is a new phenomenon or not, it has to be managed.

"It appears to be associated with high-speed lines, heavy axle loads and running around curves. This has big implications for rail usage in all areas. The questions to be asked are whether the measures taken already, such as speed restrictions, are enough or too much."

As expected, the HSE report stated that a broken rail was the cause of the crash. It found "significant metal fatigue damage to the rails in the vicinity of the derailment".

The HSE report came as Mr Coleman revealed that the derailment of a Virgin commuter train outside Stafford station on Thursday night was also the result of a broken rail. He said: "It is believed the driver saw the rail was broken and began to brake the train."

Yesterday the HSE released a letter Mr Coleman had written at the end of June this year to Gerald Corbett, the Railtrack chief executive, expressing concern about track quality and broken rails. Mr Coleman said the action which had been taken by Railtrack in the light of the letter would be a matter for the HSE's inquiry to consider.

The question of whether a speed restriction should have been in place at Hatfield would be "absolutely crucial to the investigation", Mr Coleman said.

Railtrack had agreed to have its work audited to ensure that what work the HSE asked to be done on the tracks was being done, he added. The company had also agreed that all sites scheduled for renewal of track should be assessed urgently to ensure that measures put in place in the meantime were adequate.

The HSE will take on more consultant inspectors to ensure that Railtrack keeps its promise to carry out remedial work where necessary. All the inspectors will be reminded that they have the power to take legal action if they feel the work is not being completed to schedule.

In addition to finding evidence of significant metal fatigue damage to rails in the vicinity of the Hatfield derailment, the HSE report said:

* The only evidence to date of wheel damage was consistent with the wheels having hit defective track;

* There was no evidence, so far, of a prior failure of rolling stock;

* The most extensive damage appeared to have been caused by derailed carriages impacting line-side structures;

* The signalling system appeared to have played no part in the derailment; and

* Parts of the rail and train components had yet to be recovered.

Speaking at the scene of the crash, Stan Hart, a principal inspector of railways, said that investigators would also try to establish how badly the Hatfield track was cracked or broken as the train approached. He said: "The problem is that the rail is now so smashed up and broken that it is difficult to know what damage occurred when.

"Clearly most of the weight of the train would be at the front, and it is likely that as the locomotive went over any damaged section of track it would have caused further damage."

Drivers of other trains that went over the section of track shortly before the accident would be questioned to see if they had noticed anything wrong, Mr Hart said.