Getting to the underlying causes of SPADs

20/05/2020

When we look for the underlying and contributory factors of a Signal Passed At Danger (SPAD), our understanding of the incident becomes much clearer. By considering both individual and organisational factors, we can make suitable recommendations to reduce the risk of such an event happening again.

SPAD investigations have traditionally focused on understanding what happened. They identify each step in the sequence of events that lead to the unwanted incident. Identifying the ‘what’ is important but does not always give us the full story. We also need to find out why each step happened. This approach often requires more time and perseverance, but the reward is a clearer understanding of the underlying causes.

In the rail industry, as in any safety critical industry, the human is the last barrier of defence. It is therefore usually easier to identify the failings in human performance, and make recommendations targeted at the individual, such as a development plan. By identifying the underlying causes of SPADs at the organisational level, we are able to make recommendations that can be included in the safety management system (SMS). Looking at both individual factors and organisational factors in a balanced way allows us to make changes to mitigate against a wider range of factors.
Balanced-image

Underlying factors can span the whole framework of an organisation’s SMS. The industry ’10 incident factors’ framework organises these organisational factors into 10 key risk areas, including processes and procedures; fatigue, health and wellbeing; and the design of infrastructure or vehicles. Businesses can mitigate against the risk of these organisational factors to support individuals, so that they can perform their tasks as safely and reliably as possible.

When we identify the organisational factors that need to be improved and developed, we shift the focus to supporting all individuals that are likely to experience a similar situation in the future. This can require a cultural change: the organisation needs to see incidents as something that they can control through their SMS rather than something which arises out of human errors by staff.

The safety risk profile will vary depending on many factors including the company’s type, size, and industry sector; and the roles of the individuals. Industry as a whole also benefits from identifying underlying factors, as we reliably identify SPAD cause profiles and trends. For example, if there is an issue with post qualified (PQ) drivers, data on underlying causes can help us understand if this relates to deeper issues around competence management processes, fatigue management, or signalling layouts.

Taxonomies like the ‘10 incident factors’ provide new insights into the underlying causes of rail incidents and the different risk factors. By understanding the underlying causes of SPADs, we can learn from operational experience and use it to inform best practice and strategy on SPAD prevention.