Human Factors and Ergonomics

Prior to the 1940’s, the equipment that people used was relatively simple. Humans could easily adapt to every design and make it work.

During the 2nd world war, equipment became more complicated and humans had difficulty adapting to it. There were many accidents and injuries because of the complexity.

Governments on both sides of the Atlantic recognized the problem and brought together teams consisting of physiologists, psychologists, engineers and physicians to solve them. This was the start of Human factors.

In Europe, this new science was called Ergonomics which means the laws of work. In North America, the science was called Human Factors Engineering

Today, most specialists in this area consider the terms – Human Factors and Ergonomics - equal in every sense.

What is Human Factors

Human Factors is defined as the “systematic process of designing for human use”. The process applies our knowledge of the capabilities, limitations and needs of people to the equipment they use, the environments they operate in, the tasks they perform and the management systems that guide the safe operation of their plants

Why is human factors important?

Human Factors considers human users first in every piece of equipment and in every system we design.

By putting the human user at the center of the design and then designing from the center out, we consider human capabilities, limitations and needs at every stage of the design, in every type of environment that the system operates, and during each aspect of the task that humans perform while operating the equipment.

By using this human-centered approach, equipment is easier to use, fewer operating errors occur and the number and severity of injuries that users suffer are reduced.

Midland Engineering Limited has specialist that can work with you to apply Human Factors analysis and implement improvements in the following areas:

Project management


Human Factors is most usefully applied during the design of capital and local projects. MEL specializes in the application of Human Factors Engineering during the life cycle of a project. We have developed many specialized tools to assist project personnel to design and build process facilities including:

  • Human Factors Engineering Design Guidelines
  • Procedures Design Guidelines
  • Processes for the implementation of computer model reviews
  • Human Factors training for owner and consulting personnel
  • Critical Task Identification and Analysis (CTIA)

Over the past 20 years, we have applied this knowledge to capital projects for most major integrated oil companies.

For a more complete description on how to apply Human Factors Engineering in Projects, the reader is referred to Chapter 9 in  Attwood, D.A., Deeb, J.M and Danz-Reece, M.E. “Ergonomic Solutions for the Process Industries” Elsevier, New York, 2004.


Critical Task Identification and Analysis (CTIA) is a systematic method of identifying high risk tasks within a process facility, prioritizing their importance, analyzing the tasks for inherent risks and identifying appropriate safeguards to mitigate the risks. Critical tasks may have the potential for personal injury, equipment or facility loss, environmental release, community exposure or business interruption.

For more information on the CTIA process, the reader is invited to read Chapter 5 of the book co-authored by C. FRANKLYN-ALDERMAN and D. ATTWOOD for the Center for Chemical Process Safety,  CCPS, “A practical approach to Hazard Identification” John Wiley and Sons, New York, 2010”


American Petroleum Institute (API) contracted our consultants to improve the way in which Human Factors was integrated into the PHA process.

The principle objective of the Hazard and Operational Review (HAZOP) Process is to identify process hazards, especially those that affect containment integrity. Many hazards, however, are a result of poor human factors design either with the process equipment itself, with the operations procedures or with instrumented process control. Since most HAZOPs are less systematic than they should be for addressing HF concerns, this tool focuses on Human Factors (HF) concerns associated with particular pieces of equipment while the HAZOP is in progress. For more information on including HF in the HAZOP process, please review the API document:

API (2004) Tool for incorporating Human Factors during Process Hazard Analysis (PHA) reviews of plant designs. API PHA-1, Standard by American Petroleum Institute. (Prepared for API by DENNIS A. ATTWOOD)


Project Managers agree that no matter how well a project is documented or how tight it is managed, contractors who install electrical cables and small bore piping during the last stages of the project are responsible for the most errors in plant construction. These errors result in a high number of ‘punch-list’ items that delay project completion and increase project costs.

Our consultants have developed a program to address field-run issues that consist of short, specialized contractor training programs, containing installation examples, a reminder card that is carried by each contractor and a monitoring program to quickly identify violations and have them corrected.

For more information, please read ATTWOOD, D.A., Field-run Facilities Human Factors Training “Let’s Do It Right The First Time” Presented at the Contractor Safety Seminar, Victoria TX, December 4th, 2003

Information Systems


MEL consultants have been conducting Human Factors Training for process personnel since the 1990’s.  The training program that we have developed familiarizes participants with the capabilities, limitations and needs of human operators, maintenance technicians, plant management, safety and hygiene personnel and project engineers and technical leads. Training topics include general issues such as access to equipment, manual handling, and working in hot environments as well as specific issues such as valve design, control room and control system design and loading racks.


The principles of Human Factors can be applied in any operation where humans interact with their working environment. None is more important for the proper use of Human Factors than the process control area. Since the early 1990’s, our consultants have been analyzing and redesigning control rooms and process control systems based on specialized tools designed for the task. We also have tools to ensure that control room operators, who are the key to effective operation of the process control system, are properly trained, provided with effective communication systems and have balanced workloads.

For more information, please read:

ATTWOOD, D.A. and FENNELL, D. Cost effective control room analysis techniques. Presented to the 38th Annual Meeting of the International Process Safety Group. Houston, TX, March 1999.

Workplace Systems


One constant in every process plant is the high number and diversity of valves that control the flow of feedstock, products and service liquids and gases.  The ergonomic issues associated with the design, operation and maintenance of valves include:

  • Physical stress to open and close them
  • Potential for injuries and subsequent related costs
  • Lack of access to process critical valves
  • Potential for process upsets when valves cannot be operated in the time required

MEL consultants have developed a tool to assess the musculoskeletal risk associated with manually operated valves, then to rank each valve according to the injury risk each poses to plant operators and maintenance technicians. Clearly, valve repair and replacement is expensive. So, plant management can use this ranked list to prioritize valve maintenance, addressing the worst valves first thereby reducing maintenance costs.

For more information on the risk analysis tool, please read  ATTWOOD, D.A. and TYS, A.T. (2013)A Method for Ranking the Musculoskeletal Risk of Operating Valves in Process Industries.”  Society of Petroleum Engineers, SPE-165690-MS


Designing to reduce physical injuries in a process plant involves study, analysis and application in two specialty areas – Manual Materials Handling (MMH) and Cumulative Trauma Disorders (CTD).

MMH injuries involve overexertion while lifting, lowering, pushing, pulling, carrying and holding. These tasks typically result in acute injuries (strains, sprains, tears or bruises). Lifting is considered the most “at risk” task because it involves each of the major joints associated with acute injuries.

CTD are the result of repeated micro-injuries to the soft tissues of the body (muscles, ligaments, tendons and nerves ) as a result of repetitive tasks that stress the tissues  without giving them the opportunity to heal. The result is a full, debilitating injury.

MEL personnel are specialists in the application of each of the tools that are used to analyze MMH and CTD disorders and are expert in making recommendations to improve tasks that generate each type of disorder. For more information on the effects of Musculoskeletal injuries, please read

ATTWOOD, D.A. and FENNELL, D., Ergonomic Considerations in Physically Demanding Jobs. Canadian Society of Safety Engineering Professional Development Conference, November 2003, Saskatoon, Saskatchewan


The managers and workers of pipelines companies in five different countries, have developed a list of the 25 most important Human Factors Issues that pipeline companies face in the design, construction, operation and maintenance of pipelines. MEL personnel were part of this important effort which is documented as follows:

ATTWOOD, D.A. and FRANKLIN-ALDERMAN, C., (2012) “Human Factors Influences on Pipeline Damage Users’ Guide.”  Prepared for the Pipelines Research Council International (PRCI).

MEL has developed the 25 pipeline issues recommendations, into a series of Gap Analysis questions that allows pipeline companies to determine how safe and efficient their operations are. The Gap Analysis process can be applied by a dedicated team of specialists who use accepted auditing techniques for evaluation, or by applying the process as an employee questionnaire to obtain first-hand  opinion on the health of their companies.

Human Factors

For more information contact Midland Engineering Limited @ (989) 837-2296