Articles

Articles

A set of computer based tools identifying and preventing human error in plant operation

by David Embrey, Sara Zaed

This paper describes a set of techniques, supported by computer based tools, for predicting and preventing human errors in gas plant operations. The first two tools allow an analysis of the task structure and prediction of the errors that could arise at a task or subtask level, together with the potential consequences of these errors. The third tool develops a profile of the factors in the situation (e.g. workload, fatigue, distraction levels) that affect error probability, and the most cost effective interventions to reduce errors. The software is able to provide an estimate of the likelihood of the errors occurring. A simple graphical analysis method is provided as part of the toolset to support the analysis of accident sequences in retrospective analyses. The paper includes case studies illustrating the application of the tools to gas plant operations and the measurement of mental workload of bridge crews in shipping operations.

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Causal models which affect the quality of incident investigations

by Karen Wright, Claire Whittington, Jamie Henderson

Human Reliability was commissioned by the Health & Safety Executive to carry out a survey of current industry practice in incident investigation, given the proposed new duty to investigate. This article outlines how the model of accident causation that an organisation or individual holds can have an impact on the overall quality of an investigation. Two approaches to incident investigation based on causal models at opposite ends of a spectrum are discussed and illustrated with case studies.

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CARMAN - A Consensus based Approach to Risk MANagement

by David Embrey

The first section of the paper discusses the relationship between `Best Practice` and formal procedures in high-risk systems such as chemical processing, aerospace and transportation. The results of a survey, which addressed the factors influencing the use of procedures in a high-risk industry, are described. This and other evidence shows that there is often a wide disparity between the formal written procedures in an organisation and the ways in which the work is actually carried out. This has major implications for the control of risks and the maintenance of quality. The paper describes how a culture can be created in which operations staff actively participates in assessing the risks in the system and developing best practices to control these risks. The buy-in provided by this process creates a culture where best practices become the preferred practices. A comprehensive description of this process, called CARMAN (Consensus based Approach to Risk Management) is provided, together with a set of case studies illustrating its application.

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Data Collection Systems

by David Embrey

The function of this document is to provide an overall framework within which to describe the important aspects of data collection systems. The emphasis on data collection in this document will be on methods for identifying the causes of errors that have led to accidents or significant near misses. This information is used to prevent the reoccurrence of previous accidents, and to identify the underlying causes that may give rise to new types of accidents in the future. Data collection thus has a proactive accident prevention function, even though it is retrospective in the sense that it is usually carried out `after the event` (an actual accident or near miss).

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Getting at the underlying systemic causes of SPADS: A new approach

by Karen Wright, David Embrey & Martin Anderson

Now, more than at any other time in the history of the railways, there is an urgent need for the industry to learn lessons from near misses and incidents. In this first of two articles, we examine the extent to which the current procedures for gathering data on accidents such as SPADs provide support for the identification of underlying causes. An alternative approach is outlined, which we believe has the potential to allow a much more comprehensive and structured assessment of underlying causes to be made during SPAD investigations. This process is based on the research findings on the causes of SPADs, combined with the practical knowledge possessed by experienced personnel such as drivers and Driver Standards Managers.

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Incorporating management and
organisational factors

by David Embrey

This paper is concerned with how management and organisational influences can be factored into risk assessments. A case study from the rail transportation sector illustrates how organisational factors can act as high level influences which are manifest as operational errors giving rise to major accidents. A model is proposed which describes the interrelationships between management influences, immediate causes and operational errors. This model can be used for organisational auditing, monitoring and system design. A strategy is described for collecting data from an existing organisation to develop a specific form of the generic model. The final issue addressed is the use of the model to quantify the effects of organisational influences on risk arising from human error. A numerical case study is provided to illustrate the approach.

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Introduction to performance influencing factors

by David Embrey

Performance Influencing Factors, or PIFs, are factors that combine with basic human error tendencies to create error-likely situations. In general terms PIFs can be described as those factors which determine the likelihood of error or effective human performance. It should be noted that PIFs are not automatically associated with human error. PIFs such as quality of procedures, level of time stress, and effectiveness of training, will vary on a continuum from the best practicable (e.g. an ideally designed training program based on a proper training needs analysis) to worst possible (corresponding to no training program at all). When PIFs relevant to a particular situation are optimal then performance will also be optimal and error likelihood will be minimised.

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Systems for predictive error analysis

by David Embrey

It is widely recognised that human error in industrial operations is a major source of risk that needs to be considered when plants are designed, modified or operated. The increasing interest in this area has arisen partly from the occurrence of a number of major accidents where human error has played a significant role, but also as a direct result of recent safety legislation. A means for the proactive identification of areas where the potential for these errors exist would therefore be very useful. The paper presented here describes such a tool, the programme for its introduction to a site, and some results of its application and use. The tool itself assesses the potential for error by systematically assessing the factors which influence human performance and has been designed to be used by plant personnel with minimum training. It is introduced into a plant in conjunction with the work force, who have an active part in its application, and once this has been done they become owners and users of the tool.

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Task analysis

by David Embrey

Task analysis is a fundamental methodology in the assessment and reduction of human error. A wide variety of different task analysis methods exist, and it would be impracticable to describe all these techniques here. Instead, the intention is to describe representative methodologies applicable to different types of task.

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Understanding human behaviour and human error

by David Embrey

A paper concerning error types and classifications with a focus on a number of models of human performance such as Generic Error Modelling System and the Step Ladder Model.

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Human Reliability Quantification

Addressing human reliability quantification issues in COMAH reports
using the SHERPA and SLIM methodologies