HOF in event investigation

Introduction 

Event investigation is a central component of safety management systems. Events may be accidents (eg slips/trips/falls or train collisions), incidents (eg trains overrunning a station) or near miss events. Investigations aim to identify the underlying causes of events and develop recommendations to reduce the likelihood or mitigate the consequences of the event re-occurring. These recommendations are actions to change and improve company processes and are essential to effective risk control and learning.  

Human and Organisational Factors are a key part of competence for event investigators. Two key reasons for this are: 

• Human performance is often an immediate cause of events and understanding human performance from a Human and Organisational Factors perspective is central to the investigation process. 
• The use of a human factors approach leads to a consideration of the wider job/workplace and organisational factors which may have contributed to an event, looking past human performance at the front line. Identifying these deeper underlying causes will lead to more effective recommendations which help improve the overall safety management system and promote a fair culture, rather than just focusing on fixing an error by front line staff.  

Relevance to rail 

Railway accidents are frequently shown to have multiple causes related to HOF. Significant examples include the Awash train derailment (Ethiopia, 1985), Waterfall train accident (Australia, 2003), Eckwersheim derailment (France, 2015) and Labroke Grove train accident (UK, 1999). As an example of the types of factors identified in these incidents, the Ladbroke Grove accident identified causes related to inadequacies in the consideration of human performance when designing railway signals, weaknesses in the development of competence management processes to support train driver route knowledge development and wider issues around safety culture. Railway standards and regulations also recognise the importance of considering HOF in relation to incidents, for example, “… human behaviour plays a central role in the safe and efficient operation of the railway. Where that behaviour is considered to have contributed to an accident or incident, it may be that organisational factors, such as workload or job design, had an influence on that behaviour, and thus led to a lesser performance and aggravation of the consequences of that accident or incident. “ (European Commission, 2018) 

Approaches and models 

A range of human factors methods can be applied during investigations and a useful guide relevant across industries is presented in a white paper on learning from adverse events. Human Factors frameworks can be particularly useful for guiding investigations and railway examples include “The SAfety FRactal ANalysis (SAFRAN) method “(Accou and Carpinelli, 2022) and the human performance and 10 incident factors (RSSB, 2022). There are also generic HOF frameworks that can be used for event investigation, particularly the Human Factors Analysis and Classification System (HFACS). Methods which aim to support and structure the data collection and analysis phases of investigations processes from an HF perspective include Accimaps (Branford et al, 2011) and STAMP (System Theoretic Accident Model and Processes) (Altabakkh et al, 2014).