| CASE STUDIES |
| BENNERLEY DERAILMENT INVESTIGATION (FRACTURED AXLE) |
| Background |
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| On Friday 21 June 2002, an 1800 tonne, 36-vehicle,
coal train operated by EWS derailed at Bennerley
Junction, 2 miles south of Langley Mill Station,
Derbyshire. Initial investigations revealed the
cause of the derailment as a fractured axle on
the 23rd vehicle. The subsequent metallurgical
investigation on the fractured axle revealed it
had failed through classic bending fatigue. ESG
(the technical department of EWS at the time)
was asked to project manage the technical aspects
of the investigation and recommend actions to
prevent any further incidents. |
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| Project Overview |
| ESG produced the specification and managed the metallurgical
examination of the axle by 2 specialist subcontractors. The
results cast doubt over the reliability of the last NDT inspection
of the axle and ESG was involved in the subsequent audit of
the location concerned. The results prompted EWS to review
their NDT policy and ESG supported this by producing a review
and risk assessment of the current practise and investigation
of alternative techniques. |
| The risk assessment included fracture mechanic simulations
in collaboration with nCode International and a Human Factors
Analysis of MPI with experts from RSSB. The risk assessment
was used to prioritise NDT inspections on the entire rolling
stock fleet, and proved to be an accurate and efficient method
of locating 'at risk' axles. Based on ESG's recommendations
and support, EWS implemented a new phased plane eddy current
NDT technique (ECT), which was then used to test axles in
the field as well as being introduced at routine inspections
at overhaul. ECT proved to be a highly sensitive and accurate
technique. The results of the investigation not only made
fatigue flaw detection more reliable, it was also possible
to remove other inspections that were proven to be unnecessary,
thereby also saving cost. |
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| Key Features |
- Specification, management, analysis and reporting of
metallurgical investigation
- Selection and control of expert third-party sub contractors
- Audit of NDT facilities
- Axle stress calculations and analysis
- Fracture mechanics - crack growth rates in axles
- Risk Assessment
- Human Factors Analysis
- Review of established and emerging NDT technologies
- Implementation of new NDT technologies
- In-service monitoring and control of cracked axles
- Investigation and analysis of vehicle maintenance histories
- Liaison with regulatory bodies
- Consultation and communication with relevant industry
parties
- Documentation and reporting
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| Skills Profile |
- Project Management
- Risk assessment
- Peer review of technical documentation
- Documentation (including policy papers)
- Investigation and analysis of NDT technology (UAT, MPI
and eddy current)
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| Further information contact Robert.Morley@esg-railconsultancy.co.uk |
| Photographs and project detail reproduced by kind permission
of English, Welsh & Scottish Railway Ltd. |
