HSE making progress with Potters Bar investigation

The Health and Safety Executive (HSE) has published a progress report on its investigation into the Potters Bar derailment, but cannot reveal everything because of the "ongoing British Transport Police-led investigation".

Dr Mike Weightman, chair of the Investigation Board, said: "We wish to be open about our work, though much of the detailed findings cannot be revealed yet as this may jeopardise the ongoing British Transport Police-led investigation."

"It is too early to pronounce definitively on the direct or root cause of the accident but the Board judges it should put into the public domain the information that it can and make preliminary recommendations about improvements to the safety of the rail network," he added.

The main findings so far include:

• The derailment resulted from faults (nuts missing from adjustable stretcher bars) in the points which caused them to fail catastrophically;
  
• Detailed examination of the points has identified other differences in their condition compared to the standards expected;
  
• Tests of a sample of nuts on the adjustable stretcher bars of other points in the Potters Bar area revealed that 20% were not fully tight;
  
• HSE's HM Railway Inspectorate (HMRI) conducted a sample inspection of points across the rail network which found differing standards in conditions and maintenance arrangements, including record keeping. 

HSE's investigation is currently focusing on technical information coming from the detailed examination and testing of the set of points involved in the derailment, but work also continues on looking at the wider managerial issues that may have contributed to the accident.

The Board's preliminary recommendations are that Railtrack and its contractors should co-operate to review the arrangements for ensuring that points are compliant with the standards and specifications expected.

In the short term, Railtrack should review the design arrangements for points with adjustable stretcher bars to better ensure that good engineering standards are achieved and maintained, and in the longer term, Railtrack should review the design of adjustable stretcher bars to see if they can be replaced by a more inherently safe design.