Error reduction

Another reason for investing in error reduction is to conform with regulatory standards. Error reduction yields regulatory relief. 

The book begins with a discussion of the theories of error causation and then goes on to describe the various ways in which data can be collected, analyzed, and used to reduce the potential for error. Case studies are used to teach the methodology of error reduction in specific industry operations. Finally, the book concludes with a plan for a plant error reduction program and a discussion of how human factors principles impact on the process safety management system. 

Chapter 8, A Systematic Approach to the Management of Human Error, explains how the manager and safety professional can use human factors principles in the management of process safety. This chapter also provides a practical plan for a plant human error reduction program that will improve productivity and quality as well. 

An additional reason for investing resources in error reduction measures is to improve the ability of the industry to conform to regulatory standards. It is likely that as the relationship between hximan error and safety becomes more widely recognized, regulatory authorities will place more emphasis on the reduction of error-inducing conditions in plants. It is therefore important that the Chemical Process Industries take the lead in developing a systematic approach and a defensible position in this area. 

FROM THEORY TO PRACTICE TURNING THE SYSTEMS APPROACH TO A PRACTICAL ERROR REDUCTION METHODOLOGY... 

In subsequent chapters, the various theories, tools, and techniques required to turn the systems approach from a concept to a practical error reduction methodology will be described. The components of this methodology are described in Figure 1.7. Each of these components will now be described in turn, together with references to the appropriate sections of the book. 

The first component of the systems approach to error reduction is the optimization of human performance by designing the system to support human strengths and minimize the effects of human limitations. The hiunan factors engineering and ergonomics (HFE/E) approach described in Section 2.7 of Chapter 2 indicates some of the techniques available. Design data from the human factors literature for areas such as equipment, procedures, and the human-machine interface are available to support the designer in the optimization process. In addition the analytical techniques described in Chapter 4 (e.g., task analysis) can be used in the development of the design. 

The last area addressed by the systems approach is concerned with global issues involving the influence of organizational factors on human error. The major issues in this area are discussed in Chapter 2, Section 7. The two major perspectives that need to be considered as part of an error reduction program are the creation of an appropriate safety culture and the inclusion of human error reduction within safety management policies. 

As discussed earlier in this chapter, the main requirements to ensure an appropriate safety culture are similar to those which are advocated in quality management systems. These include active participation by the workforce in error and safety management initiatives, a blame-free culture which fosters the free flow of information, and an explicit policy which ensures that safety considerations will always be primary. In addition both operations and management staff need feedback which indicates that participation in error reduction programs has a real impact on the way in which the plant is operated and systems are designed. 

The first perspective is the traditional safety engineering approach (Section 2.4). This stresses the individual factors that give rise to accidents and hence emphasizes selection, together with motivational and disciplinary approaches to accident and error reduction. The main emphasis here is on behavior modification, through persuasion (motivational campaigns) or pimishment. The main area of application of this approach has been to occupational safety, which focuses on hazards that affect the individual worker, rather than process safety, which emphasizes major systems failures that could cause major plant losses and impact to the environment as well as individual injury. 

Such audits may therefore be useful as a method of increasing safety awareness and management commitment to safety as part of a more general attempt to reduce accidents. They should be treated as first steps and management must be prepared to do more than just carry out a safety audit. The authors of safety audits must be prepared to provide guidance on the next steps in error reduction once the problems have been identified. 

Depending on the results of the classification select an appropriate error reduction strategy in areas such as training, procedures or equipment design, as illustrated in Table 2.3. 

TABLE 2.3 Example Error Reduction Recommendations Arising from the SRK Model ... 

TYPICAL ERRORS ASSOCIATED WITH DIFFERENT INFORMATION PROCESSING LEVELS EXAMPLES OF ERROR REDUCTION STRATEGIES ... 

Error Prediction for Safety Analysis and Proactive Error Reduction This procedure is performed when error modes are being identified (e.g., critical action omitted, alternative imsafe action carried out) as part of a predictive safety analysis (e.g., CPQRA) or as part of a proactive error reduction process (see Chapter 4). 

For errors with serious consequences and/or high likelihood of occurrence, develop appropriate error reduction strategies. 

In subsequent sections the application of PIFs to various aspects of error reduction will be described. One of the most important of these applications is the use of comprehensive lists of PIFs as a means of auditing an existing plant to identify problem areas that will give rise to increased error potential. This is one aspect of the proactive approach to error reduction that forms a major theme of this book. This application of PIFs can be used by process workers as part of a participative error reduction program. This is an important feature of the human factors assessment methodology (HFAM) approach discussed in Section 2.7. 

This chapter has reviewed various PIFs which deterirune the likelihood of human error in the CPI. The list of PIFs in Table 3.1 can be used by engineers and managers to evaluate and audit existing work systems, analyze process incidents and generate error reduction strategies in conjunction with the techniques described in Chapters 4 and 5. 

In addition to their descriptive fimctions, TA techniques provide a wide variety of information about the task that can be useful for error prediction and prevention. To this extent, there is a considerable overlap between Task Analysis and Human Error Analysis (HEA) techniques described later in this chapter. HEA methods generally take the result of TA as their starting point and examine what aspects of the task can contribute to human error, hr the context of human error reduction in the CPI, a combination of TA and HEA methods will be the most suitable form of analysis. 

The OAET approach does not address error reduction or make any attempt to discover the root causes of the human errors represented. 

Error analysis techniques can be used in accident analysis to identify the events and contributory factors that led to an accident, to represent this information in a clear and simple manner and to suggest suitable error reduction strategies. This is achieved in practice by identification of the causal event sequence that led to the accident and the analysis of this sequence to identify the root causes of the system malfunction. A discussion of accident analysis techniques is included in Chapter 6. 

TASK STEP TASK TYPE ERROR TYPE DESCRIPTION CONSEQUENCES RECOVERY ERROR REDUCTION STRATEGY... 

For those errors with significant consequences where recovery is unlikely, the qualitative analysis concludes with a consideration of error reduction strategies that will reduce the likelihood of these errors to an acceptable level. These strategies can be inferred directly from the results of the PIF analysis, since this indicates the deficiencies in the situation which need to be remedied to reduce the error potential. 

Figure 5.9 illustrates some of the possible error reduction strategies available. Apart from the specific strategies set out in Figure 5.9, the PIF analysis also indicates which PIFs should be modified to reduce the likelihood of error. In the case of the chlorine loading example, the major scope for improvements are the reduction of time stress and distractions and the development of better quality procedures. 

The error reduction analysis concludes one complete cycle of the qualitative human error analysis component of the methodology set out in Figure 5.4. The analyst then decides if it is appropriate to perform a more detailed analysis on any of the operations considered at the current level. As a result of this process, operations 3.2 Monitor tanker following operation, 4.1 Stop filling operation, 4.2 Disconnect tanker, and 4.4 Secure tanker are analyzed in more detail (see Figure 5.6). 

The qualitative human error analysis stages described above are applied to the task steps in subtask 3.2. Examples of the results of this analysis are shown in Figure 5.8. The corresponding error-reduction strategies are shown in Figure 5.9. 

FIGURE 5.9. Error Reduction Recommendations Based on PHEA... 

ERROR REDUCTION STRATEGIES. If the error probability calculated by the above procedures leads to an unacceptable overall system failure probability, then the analyst will reexamine the event trees to determine if any PIFs can be modified or task structures changed to reduce the error probabilities to an acceptable level. 

Implementing and Monitoring the Effectiveness of Error Reduction Measures (6.9) The specification and implementation of error reduction measures arises directly from the identification of causes. The data collechon system needs to be able to evaluate the effechveness of such measures. 

The first area focuses on the cultural and organizational factors that will have a major influence on the effectiveness of a human error data collection system and how well the information derived from such a system is translated into successful error reduction strategies. Regardless of how effectively the technical issues are dealt with, the system will not be successful imless there is a culture in the organization which provides support for the data gathering process. No data collection system aimed at identifying human error causes of accidents will be workable without the active cooperation of the workforce. 

Emphasis on the Modification of System Factors as a Major Error Reduction Strategy This emphasis replaces the reliance on rewards and pLmishment as a means of error control which characterizes the TSE approach. 

IMPLEMENTING AND MONITORING THE EFFECTIVENESS OF ERROR REDUCTION MEASURES... 

---