Report 03/2020: Class investigation into human performance in signalling operations
Class investigation into human performance in signalling operations.
Summary
Since it became operational in 2005, RAIB has investigated numerous incidents in which signaller decision-making has been pivotal, and where the safety of the railway system was heavily dependent on those decisions (that is, scenarios in which there were no, or limited, engineered safeguards). Under its remit, RAIB also collected industry data on several similar incidents over a five-year period which again highlighted the vulnerable nature of such decision-making. In the light of these incidents, we undertook a class investigation into what affects those decisions, recognising that they may be influenced by a variety of systemic factors. Although this investigation is about what can go wrong, it must be recognised that front-line decisions also contribute much more widely to the safe operation of the railway on a daily basis.
The investigation examined five categories of incident:
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user worked crossing irregularities
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line blockage irregularities
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users trapped at CCTV level crossings
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irregularities involving level crossings on local control
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other operational irregularities
The investigation identified several common factors influencing the actions of signallers across these scenarios, associated with:
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signaller workload
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user-centred design
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competence management
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experiential knowledge
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organisational structure
The report also observes that Network Rail’s incident investigations do not always fully exploit the opportunities to learn from these incidents.
Recommendations
As a result, RAIB has made six recommendations to Network Rail, addressing each of the five areas listed above as well as the observation on learning from incident investigations. There is also a learning point for incident investigators relating to the identification of systemic causal factors.
Response to recommendations:
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RAIB will periodically update the status of recommendations as reported to us by the relevant safety authority or public body
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RAIB may add comment, particularly if we have concerns regarding these responses.