Root cause analysis, accidents methods

However, in the case of a root cause analysis system, a much more comprehensive evaluation of the structure of the accident is required. This is necessary to unravel the often complex chain of events and contributing causes that led to the accident occurring. A number of techniques are available to describe complex accidents. Some of these, such as STEP (Sequential Timed Event Plotting) involve the use of charting methods to track the ways in which process and human events combine to give rise to accidents. CCPS (1992d) describes many of these techniques. A case study involving a hydrocarbon leak is used to illustrate the STEP technique in Chapter 7 of this book. The STEP method and related techniques will be described in Section 6.8.3. 

In the following sections, a number of methodologies for accident analysis will be presented. These focus primarily on the sequence and structure of an accident and the external causal factors involved. These methods provide valuable information for the interpretation process and the development of remedial measures. Because most of these techniques include a procedure for delineating the structure of an incident, and are therefore likely to be time consuming, they will usually be applied in the root cause analysis of incidents with severe consequences. 

The principal role of the U.S. Chemical Safety Board is investigating accidents to identify the conditions and circumstances that led to the events. It also investigates hazardous conditions that could lead to accidents. The agency uses root cause analysis and other methods to identify causes to prevent events. It makes recommendations to government agencies, companies, trade associations, labor unions, and other groups. It publishes reports and offers DVDs about cases it investigates. 

Each accident/incident should be methodically analyzed using an accident investigation/root cause analysis approach. Because many root cause analysis methods exist, it will be the investigator s responsibility to select the appropriate analysis approach (e.g., barrier analysis). Use of proper accident/incident investigation methods and tracking will lead to intervention, which will successfully prevent further occurrence of these occupational accidents and incidents. 

In our view, Heinrichs principal contribution to the safety profession was his contention that science and engineering may be apphed practically and successfully to the prevention of accidents. He used the term science in the sense of knowledge of principles or facts. He stressed the four fundamental principles of accident prevention as (1) upper management interest and support (critical to the success of any safety program) (2) cause analysis (methods aimed at identifying the root cause of accidents) (3) selection and application of remedy (mitigation) (4) and executive enforcement of corrective practices (Hayhurst 1932). 

We will later apply the accident-analysis framework in a review of different types of methods used in the collection and analysis of data of accident risks. We will start at the output side of the model by reviewing the different types of classification systems used to document the consequences of accidents and different measures of loss. We will then continue by looking into the classification systems used to document incidents and deviations. Finally, we will review the different classification systems for contributing factors and root causes. Our aims will be twofold first, to be complete, i.e. by presenting all alternative means of measuring and classification, and second, to give specific advice on the preferred method. The reader will find recommended alternatives in shaded tables and checklists. 

We now move further to the left in the accident-analysis framework (Figure 16.1). We will look into SHE performance indicators based on information about contributing factors and root causes. The organisation and SHE management system are in focus. These indicators have many similarities to the audit methods described in Section 14.2. 

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