Human factors play a critical role in BowTie risk analysis because they influence the effectiveness of both preventive and recovery controls. In a BowTie diagram, threats can lead to a hazardous event if controls fail and many of these controls rely on human actions, decisions or behaviours. Factors such as competence, communication, workload, fatigue, situational awareness and adherence to procedures can determine whether a control performs as intended. Identifying these human influences help organisations better understand where failures are most likely to occur.
When incorporating human factors into a BowTie analysis, it is important to assess the reliability of human-dependent controls and identify the conditions that could reduce their effectiveness. Performance influencing factors such as inadequate training, poor equipment design, time pressure, distractions and unclear responsibilities can weaken critical barriers. Identifying these factors allows organisations to introduce additional controls, improve barrier reliability and reduce the likelihood of human error compromising risk controls.
People as Safety Barriers
Human Factor Specialist Ronald W. McLeod argues that human factors strengthen BowTie analysis barriers by focusing on the conditions that enable people to perform safety critical tasks successfully, rather than simply attempting to eliminate human error. He emphasises that people are an integral part of many preventive and recovery barriers and that barrier effectiveness depends on designing work systems that support reliable human performance.
Rather than viewing people as the primary source of risk, McLeod recognises that well-designed organisational systems enable individuals to adapt, make informed decisions and respond effectively to changing operational conditions. This perspective strengthens barrier performance, improves organisational resilience and supports more effective management of major accident hazards.
By considering factors such as competence, procedures, equipment design and the working environment, organisations can improve the quality and dependability of human-dependent barriers.
Managing Human Performance
Human performance is inherently variable. People become fatigued, take breaks, experience distractions and may sometimes make decisions that appear incorrect but are reasonable given the information, pressures or organisational influences present at the time. These characteristics reinforce the need to design systems that support reliable performance rather than relying solely on individual behaviour.
An example is the Energy Institute whose guidance emphasises that effective management of human factors is essential for preventing major accidents, as people interact continuously with equipment, procedures and management systems. Rather than focusing solely on individual behaviour, the Energy Institute promotes a systems approach that considers how work is designed, organised and managed to support reliable human performance.
According to the Energy Institute, integrating human factors into risk management and barrier-based approaches such as BowTie analysis helps ensure that critical controls remain effective throughout their lifecycle. This includes addressing performance influencing factors such as competence, communication, workload, fatigue, supervision, shift patterns and organisational culture. By identifying and managing these influences, organisations can strengthen both preventive and recovery barriers, improve operational resilience and reduce the likelihood of human error contributing to major accident hazards.
Supporting Human Factors with BowTie Pro
BowTie Pro supports the practical implementation of human factors by allowing organisations to explicitly identify human-dependent barriers and link them to accountable roles, competencies and procedures. This enables organisations to:
- identify where human performance is critical to barrier effectiveness
- assign accountable posts and required competencies to each barrier
- link barriers to procedures and tasks that support consistent execution
- demonstrate ownership of safety critical activities
- provide assurance that human-dependent controls are appropriately managed and maintained
- provide an Energy Institute-based Human Factors Assessment template as an alternative to modelling issues with human factors solely through Escalation Factors
Integrating human factors into BowTie analysis enables organisations to move beyond viewing people solely as a source of error and instead recognise them as essential contributors to effective risk management. By understanding both the strengths and limitations of human performance, organisations can design stronger barriers, improve operational resilience and maintain more effective control of major accident hazards. When supported by BowTie Pro, these principles can be embedded into everyday barrier management, providing greater confidence that human-dependent controls remain effective throughout their lifecycle.