In complex, high-hazard industries such as nuclear power, petrochemical refining, and defence, the narrative surrounding safety has evolved significantly. Historically, when an incident occurred, investigations often concluded with “operator error,” leading to retraining or disciplinary action. Today, we understand that human error is rarely the root cause; it is a symptom of a poorly designed system. To truly enhance safety, organisations must shift from reacting to errors to proactively managing human failure. The most effective tool for this is Human Reliability Assessment (HRA).
At Horizon Human Factors, we specialise exclusively in providing human factors consultancy and training for high-hazard sectors. This article explores the principles of HRA, the factors that influence human performance, and how specialist engineering can mitigate risk.
What is Human Factors Engineering?
Before delving into HRA, it is essential to answer a fundamental question: what is human factors engineering?
Human factors engineering (often referred to as ergonomics) is the scientific discipline concerned with understanding the interactions among humans and other elements of a system. It applies theory, principles, data, and methods to design in order to optimise human well-being and overall system performance. In high-hazard environments, this means designing control rooms, procedures, equipment, and organisational structures that align with human cognitive and physical capabilities, thereby making it easy to do the right thing and hard to do the wrong thing.
Understanding Human Reliability Assessment (HRA)
Human Reliability Assessment (HRA) is a structured methodology used within the broader field of human factors engineering to evaluate the probability of human error in specific, safety-critical tasks. It is a core component of quantitative risk assessments (QRA) and safety cases required by regulators like the HSE (for COMAH sites) and the ONR (for nuclear facilities).
HRA involves three main phases:
1.Identification: Determining which human actions are critical to safety and what types of errors could occur (e.g., omitting a step, performing an action out of sequence).
2.Modelling: Understanding the context of the task, including the cognitive demands placed on the operator.
3.Quantification: Estimating the likelihood of the identified errors occurring, often using established HRA tools and databases.
The true value of HRA, however, lies not just in generating a probability number, but in identifying the underlying vulnerabilities that drive that probability.
Human Factors Performance Influencing Factors (PIFs)
The likelihood of human failure is not static; it fluctuates based on the context in which the task is performed. These contextual variables are known as human factors performance influencing factors (PIFs).
PIFs can be categorised into three main areas:
•Job Factors: The nature of the task itself. Is the workload too high? Are the procedures ambiguous or out of date? Is the human-machine interface (HMI) confusing?
•Individual Factors: The characteristics of the person performing the task. Are they fatigued? Do they have the necessary competence and training? Are they experiencing high levels of stress?
•Organisational Factors: The broader work environment. Is there a strong safety culture? Is communication effective during shift handovers? Are staffing levels adequate?
A robust HRA systematically evaluates these PIFs. If an assessment reveals that operators are expected to perform a complex diagnostic task at 3:00 AM, using poorly written procedures and a cluttered interface, the probability of failure will be high.
Strategies for Managing Human Failure
Once HRA has identified the critical tasks and the negative PIFs affecting them, organisations can implement targeted strategies for managing human failure. This involves applying the hierarchy of controls to human factors:
1.Eliminate the Hazard: Can the system be redesigned so that human intervention is no longer required for safety?
2.Design for Error Tolerance: If human action is required, can the system be designed to tolerate errors? For example, using interlocks that prevent a valve from being opened out of sequence.
3.Optimise PIFs: Improve the working environment by redesigning interfaces, rewriting procedures to be user-centric, managing fatigue through better shift scheduling, and enhancing training programs.
The Need for Specialist Expertise
Conducting a meaningful HRA requires deep expertise in cognitive psychology, systems engineering, and industry-specific operations. Generalist consultancies often lack the nuanced understanding required to accurately assess PIFs in highly complex, high-hazard environments.
Horizon Human Factors focuses exclusively on the petrochemical, nuclear, and defence sectors. Our specialist consultants possess the domain knowledge required to conduct rigorous HRAs that satisfy regulatory scrutiny and deliver practical, actionable insights for risk reduction.
Stop reacting to human error and start managing human reliability. Contact Horizon Human Factors today to discuss how our specialist HRA consultancy and training services can enhance the safety and resilience of your operations.