Case Studies - HSL Investigations of Major Rail Accidents

At the request of HSE, HSL has been involved in the investigation of several major rail accidents. These tragic events have brought home to the country the human cost of rail accidents and highlighted the importance of rail safety.

HSL's wide range of expertise in fire science, engineering, photography and human behaviour has been brought to bear on these investigations. The findings of these investigations are having a major influence on attitudes to safety in the railway industry.

On 5th October 1999 an accident occurred at Ladbroke Grove near Paddington when a Great Western Express was struck almost head-on by a Thames commuter train which had just passed a signal at danger. The collision occurred at a closing speed of some 230km/hr and resulted in thirty-one people losing their lives and over 400 people being injured, some of them seriously. An unusual feature of the crash was the major fire which ensued, causing the leading coach on the Great Western train to be completely burnt out. From photographic, video and eye witness evidence, the HSL investigation team was able to establish that some six tonnes of diesel had been explosively released from the fuel tanks of the two trains. Furthermore, the fuel was sufficiently atomised that it could be ignited by discharges from electric power lines and other ignition sources at the crash site. The crashworthiness of the fuel tanks and the fuel ignition behaviour were further examined in a series of tests carried out using HSL's unique impact test facilities. The likely failure mode of the tanks was demonstrated and related to information obtained from the crash site at the initial impact point of the two locomotives.

As to the cause of the crash, sighting aspects of the signalling system out of Paddington were studied, paying particular attention to the window of opportunity to view the signal and the visibility of the signal itself. Information was also obtained on the tasks the Thames train driver was being asked to perform during the journey, which might have caused a distraction, his familiarity with the route and the effectiveness of the driver training provided by the train company.

The investigation took nine months to complete, the pace being dictated by the needs of Lord Cullen's public inquiry to which evidence was presented by HSL staff on most aspects of the accident.

Another major accident occurred on 17th October 2000 when an Intercity train from Kings Cross to Leeds derailed near Hatfield resulting in four deaths and many injuries. An HSL team arrived at the scene within five hours of the accident to work alongside the British Transport Police in gathering evidence to explain the cause of the crash. There was evidence that the derailment had been caused by the fragmentation of a large section of rail. Approximately 150 metres of rail were transported to HSL for detailed metallurgical examination. Attention subsequently focused on the inspection regime for the rails prior to the accident and HSL was asked to review inspection reports and the risk assessment methodology. The non-destructive test procedures were assessed and samples of rail from other parts of the network were examined. The eleven rail vehicles involved in the crash were assessed for damage, both internal and external, to understand the crash dynamics and discover whether any aspect of the vehicle design or construction was suspect. It was also important to establish whether vandalism, or the way in which the train was being driven, was a factor in the derailment.

On the morning of 28th February 2001 at Great Heck an Intercity train travelling from Newcastle to London struck a road vehicle on the line and was subsequently in collision with a northbound goods train. Ten people died in the accident and many people were injured. HSL staff attended the scene shortly afterwards to record events using video and still photography, some pictures being taken from a helicopter, and to provide engineering support to HSE.

Given the circumstances of the crash, it was agreed by HSE that the railway industry should carry out its own investigation with HSL liaising with the industry and providing feedback on progress to HSE's inspectorate. HSL reviewed the industry reports which included consideration of vehicle dynamics, crashworthiness and the goods train/passenger train interaction. Separately HSL was asked, as a matter of urgency, to assess the probability of such accidents occurring. This was done by HSL risk assessment specialists within a few days, and involved a review of all road-rail vehicle collisions in recent years.

Experience with these major rail accidents and others more recently has demonstrated the breadth and depth of HSL's technical expertise in handling complex investigations.

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