Human Factors Engineering

It is increasingly recognised that human factors issues must be considered as a central part of design. Experience shows that it is ineffective to address them as an afterthought. The risks associated with poor human factors can best be avoided by starting human factors activities as early as possible in the design process and continuing them throughout.

Human Factors Engineering (HFE) is the application of human factors knowledge to the design and construction of equipment, products, work systems, management systems and tasks. The objective is to provide equipment and systems that reduce the potential for human error, increase system availability, lower lifecycle costs, improve safety and enhance overall system performance.

Human Factors Engineering = “Integrating human factors requirements into design”

There are two main objectives to addressing HFE in the design of plant and equipment:

1. To protect the comfort, health, safety and well-being of personnel
2. To minimise the risk of design-induced human performance issues, which may lead to major incidents, other adverse events, and reliability issues.

Applying human factors to design is sometimes referred to as “human centred design” or “user centred design”. The philosophy is to design work or tasks for people (rather than trying to fit the person around the job). Designing for people requires taking into account the capabilities and limitations of people. Ensuring that there is a good fit between a person, the task, the technology and the environment will protect their health and safety, as well as optimising human performance.

Rather than rely on training, procedures, or behavioural safety approaches to reduce human failures; by matching the design of work and workplaces to the needs, capabilities and limitations of people, HFE aims to “design-out” the potential for human failure. This is one of the most effective means of preventing human failures, and can also reduce the need for administrative controls such as training or written procedures.

What happens when HFE is not addressed?

The following are common problems in the oil, gas and chemicals industries when human factors have not been considered in the design phase:

• manually operated valves are placed at an improper height and orientation
• access to equipment for ease of operation is limited
• there is insufficient space around equipment for installation or maintenance
• sight-lines for lifting and laydown from cranes are poor
• equipment layout does not support logical sequence of operations
• layouts do not support logical or efficient workflow
• there is unnecessary removal of non-failed parts to access maintainable items
• the spatial relationships between crew and equipment are not logical or effective
• equipment protrudes into walkways
• there is inconsistent orientation or placement of equipment
• storage and laydown areas are insufficient
• signage and labelling are not visible from normal work areas
• stair, ladder, steps and walkway designs are not suitable.

Case study: The design of medical devices

In the healthcare sector, human error in the use of medical devices is an increasing area of concern. These devices, used for the observation and treatment of patients, may have been developed without considering how they might be used and by whom. Medical devices are operated by a wide range of users, including patients themselves in the home environment. 

A lack of human factors input into these devices may result in them being counter-intuitive, difficult to learn, and difficult to use – leading to errors and impacts upon patient safety. The Design for Patient Safety initiative in the UK looks at how better design can reduce risk, improve the working environment, and ensure better, patient-centred care.

In April 2020, the UK Chartered Institute of Ergonomics and Human Factors (CIEHF) produced guidance on human factors for the designers and manufacturers of ventilators for Covid-19. This document outlines seven key topics, including the user interface, the environment, the task, the risks, instructions and training. Although written for a very specific application, the advice and guidance in this document would be helpful in the design of many other products.

Error resistant and error tolerant

Equipment, workplaces and systems should be designed so that they are error resistant and error tolerant.

Error resistant: as far as possible, the design should protect users from making errors. To make something error resistant is to make it difficult for the user to make an error. This may include simplicity in the design and reducing the number of options available to the user. Also, the correct way to perform a task should be the easiest way, to encourage compliance. Designing equipment or a system to be error resistant is the preferred option.

Examples of error resistant design include a component that can only be assembled or inserted in a certain way, such as inserting a three-pin plug into an electrical socket. The shape and location of the pins usually makes it impossible to insert the plug incorrectly. This design makes it easy for users to do the right thing – as there is only one option, errors are impossible. This approach to design also reduces the amount of training that users require.

Error tolerant: the design should minimise the consequences of any human errors that are committed. This may include making an error more obvious to the people who committed the error, or making it visible to a supervisor or someone checking the work of the first person. In this case, the person receives feedback in a timely manner so that they can take the appropriate action. An error tolerant design should also ensure that any potential errors can be recovered from with minimal consequence.

Mental models and expectations

If equipment and systems are designed so that functions are obvious to the user, they will be able to understand how to correctly interact with the system with minimal training. Designs should also be consistent with the mental models of users: in other words, things work or perform as the user expects. We use mental models to help us understand the world around us. Where designs are consistent with how people expect them to behave, human reliability is increased. This expectation may be as a result of experience with similar equipment or systems.

If a design is intuitive, if it simply ‘makes sense’, then human performance will be improved.

For example, if the turn-signal indicators are located on a left-hand stalk in your vehicle, but on a right-hand stalk in a vehicle that you hire at the airport, it’s likely that you will operate the wrong stalk at least once! Instead of signalling your intention to turn, you may inadvertently operate the windscreen wipers. (Psychologists call this a strong stereotype takeover).

In the short video below, Senior User Experience Specialist Aurora Harley explains mental models in relation to designing a user interface, such as a website.

In designing a complex system, designers may consult with potential end users in order to avoid creating a gap between the user’s and the designers mental models. The things that people know well, and are practiced at, tends to stick – and it can be difficult to change a user’s mental models. If a design does not comply with strong user expectations, this mis-match will need to be explained by the designer either on the device itself, in the instructions, or through training.

Key questions to evaluate a design

In order to evaluate a design, it is helpful to ask the following three questions, to understand who is doing what:

Human factors engineering requires two aspects to be considered when reviewing a design. First, the physical specifications: we can assess how the design supports people to do things; for example, does the design allow people to move around the facility safely and efficiently? Can people get to the task – and get their eyes and hands on the task? Second we need to consider the cognitive specifications; for example, does the design support people to make the right decisions? Can people understand what’s happening now – and what might happen next?

The table below outlines some of the key questions that you could ask in order to assess a potential design. Think about different types of users (e.g. installer, operator, maintainer) when asking these questions, as their requirements may differ.

Design flaws and other Performance Influencing Factors

Humans are very adaptable, and often ‘create safety’ from an unsafe world – enabling users to work around poor design. However, design flaws will often have more impact on human performance when the user is fatigued, distracted, experiencing a high workload, in a stressful or emergency situation, or if they only use the equipment or system rarely. These Performance Influencing Factors can be identified and managed.

Considering human factors during the design can create equipment and a workspace that functions in a way that is intuitive for people. When the task or the work environment has not been designed with users in mind, the consequences can be disastrous, for example, see the many design issues that contributed to the Buncefield incident.

What tools or approaches are used in HFE?

The following tools are widely used in HFE, particularly in the oil, gas and chemical industries:

• Critical Task Analysis (CTA)
• Valve Criticality Analysis (VCA)
• 3D modelling
• Workload assessment
• Staffing assessment
• Link Analysis
• Training Needs Analysis
• Alarm system review.

How is HFE different to Human Factors Integration?

Human Factors Integration (HFI) provides an organising framework to help ensure that all relevant human factors issues are identified and addressed in a timely and appropriate manner throughout a project. HFI brings together a range of subjects on a major project – such as staffing levels, training and competence, workload, job design and procedures – together with the design of equipment, facilities and systems.

HFE is therefore often seen as part of Human Factors Integration, and should be included in a Human Factors Integration Plan (HFIP). Such a Plan documents how human factors integrates with other topics; the organisation of human factors capability; what human factors analysis will be done, when and by whom; and outlines the key human factors deliverables.

More information on HFE

Infographic – Human factors guidance for Covid-19 ventilator design. Chartered Institute of Ergonomics and Human Factors (CIEHF), April 2020. This one-page infographic neatly summarises four Human Factors issues to consider throughout the design process. Although produced for the design of Covid-19 ventilators, this document could inform the design of a wide range of products and equipment.

Human factors in the design and operation of ventilators for Covid-19. Chartered Institute of Ergonomics and Human Factors (CIEHF), April 2020. This document provides designers and manufacturers of ventilators with overarching advice and guidance on the key themes for consideration and specific Human Factors issues in a period of “crisis management” requiring rapid design and production. Although written for a very specific application, this document will be helpful in the design of many other products.

Human Factors Engineering in projects. IOGP Report 454, International Association of Oil and Gas Producers (IOGP, 2011). This report provides a practical, cost-effective and balanced approach to applying HFE on oil & gas projects. The report outlines how HFE is applied throughout the project lifecycle; provides examples of issues arising from a failure to address HFE; and describes typical HFE activities. Most of the guidance in this report is applicable to industries other than oil and gas. The Second Edition (June 2020) is free to download from here.

Human factors integration – Implementation in the onshore and offshore industries. Research Report 001 (HSE, 2002). This aim of this document is to provide guidance for the integration of human factors principles into the onshore and offshore system design and development process. This document outlines some features of the approach taken by the UK and US defence industry to integrate human factors into the mainstream of system development. It also provides a checklist of questions that address whether the approach to system design and development adopts best practice in human factors.

Work places and work environment. Office for Nuclear Regulation, (ONR, 2014). NS-TAST-GD-062 (Rev2). This Technical Assessment Guide is intended to support ONR inspectors (particularly Human Factors Specialist Inspectors) in assessing a nuclear licencee’s arrangements. It includes a framework for assessing workspace design and the links between workplace design/environmental factors on human performance.

Human Factors Integration. Office for Nuclear Regulation, (ONR, 2014). NS-TAST-GD-058 (Rev2). This Technical Assessment Guide is intended to support ONR inspectors (particularly Human Factors Specialist Inspectors) in assessing a nuclear licencee’s arrangements. It provides advice on assessing Human Factors Integration (HFI) methods, the human factors integration plan and the capability of those persons undertaking these HFI activities. 

Human Factors Integration – General Requirements. Transport for NSW have published a suite of standards on human factors integration (New South Wales Government, Australia). This particular standard (T MU HF 00001 ST, 2014) outlines the general requirements for application by engineering organisations intending to provide services and assets to Transport for NSW. It outlines a human factors integration process and provides requirements on topics such as anthropometric data, controls and displays, alarms and alerts, workspace design and task design.

NORSOK Standard – Working Environment. S-002 (Standards Norway, Rev. 4, August 2004). www.standard.no/petroleum. The purpose of this NORSOK standard is to ensure that the design of the installation promotes the quality of the working environment during the operational phase. It applies to the design of new installations and modification or upgrading of existing installations for offshore drilling, production, and and pipeline transportation. This NORSOK standard stipulates design requirements related to the working environment of petroleum installations as well as requirements regarding systematic management of working environment issues in project development and the design process.

Good work design handbook, Safe Work Australia (2015). This handbook contains ten principles which demonstrate how to achieve good design of work and work processes. Each is general in nature so they can be successfully applied to any workplace, business or industry. The ten principles for good work design are structured into three sections (i) why good work design is important, ii) what should be considered in good work design, and (iii) how good work is designed.

Managing the work environment and facilities, Code of Practice, Worksafe Australia. (2011). This Code provides practical guidance for persons conducting a business or undertaking on how to provide and maintain a physical work environment that is without risks to health and safety. This Code covers the physical work environment, such as workspace, lighting and ventilation; facilities for workers, including toilets, drinking water, washing and dining areas, change rooms, personal storage and shelter; remote and isolated work and emergency plans.

Lessons from high hazard industries for healthcare, National Patient Safety Agency, March 2010. This report is a summary of lessons from other high hazard industries and focuses on how a user-centred approach to design can help improve safety in healthcare by systematically addressing the system and design factors that can lead to human error. The report describes principles and processes that can be used in developing a user-centred approach to the design of healthcare facilities. Decision-makers involved in the planning, design and development of healthcare facilities will find examples of practice from other safety-critical industries on how to consider human factors at each stage of facility development.

Design Issues in Work-Related Serious Injuries. The Australian Safety and Compensation Council (ASCC), November, 2005. This is the second report arising from an ASCC project to consider the contribution of design issues to the occurrence of work-related injury and fatalities in Australia and the way that contribution may best be measured and monitored.
It contains four chapters on:

• A review of relevant literature on the role of design in serious work-related injury
• A detailed analysis of work-related fatal injury related to design, with particular focus on the construction, transport and storage, manufacturing and health and community services industries
• Consideration of poor procurement practices in relation to design issues, and
• Review of information barriers to monitoring design-related occupational injury and the proposal of approaches to reducing them.

The report concludes that similar design problems are involved in many fatal incidents, design is an important contributor to fatal injury in many industries, and solutions already exist for most of the identified design problems.