Root Accident Causes

High risk acts and conditions are the immediate causes of accidents. They are the obvious causes, or the causes that lead to the contact with a source or sources of energy. Immediate causes are the result of often deep-lying root causes. 

Employees should be encouraged to report any safety issues, such as high risk work conditions and behavior as well as safe work. Having employees report safety deviations is almost like having a workforce of safety inspectors. 

Training sessions on the basics of near miss incident philosophy and benefits, as well as how and what to report, should accompany the introduction of the system. 

A suitable form and other reporting methods should be provided before introducing a near miss incident reporting system and a management standard should be published indicating responsibilities and accountabilities for the various aspects of the system. 

Acknowledgment of receipt of the report should be forthcoming and the followup actions taken or where they are delegated should appear on some form of master tracking sheet that is publicized on a regular basis. 

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The basic Domino Model is inadequate for complex systems and other models were developed (see Safeware [115], chapter 10), but the assumption that there is a single or root cause of an accident unfortunately persists as does the idea of dominos (or layers of Swiss cheese) and chains of failures, each directly causing or leading to the next one in the chain. It also lives on in the emphasis on human error in identifying accident causes. 

In this conception of safety, there is no root cause. Instead, the accident cause consists of an inadequate safety control structure that under some circumstances leads to the violation of a behavioral safety constraint. Preventing future accidents requires reengineering or designing the safety control structure to be more effective. 

His premise that psychology lies at root of sequence of accident causes (Citation 4)... 

Previously, I quoted the following phrase, which is at the beginning of a paragraph in all of Heinrich s editions Psychology lies at root of sequence of accident causes. In that paragraph, Heinrich said that ... 

Figure 10.1 highlights the luck factor that determines the outcome of an undesired event, the important role that near-miss incidents play in loss prevention, and the importance of the accident root causes and their antecedents. This model will help managers look at the bigger picture of accidental loss—the causes, effects, and luck factors—and explains the importance of risk identification and mitigation in the safety process. Similar models on loss causation can be referred to as long as they focus on the bigger picture and do not indicate unsafe employee actions as the main accident causes. 

On the TRIPOD website (http //www.energypublishing, org/tripod), the method is described as a theory (sic ) for understanding incidents and accidents, in particular to allow the root organisational causes and deficiencies to be uncovered and addressed. TRIPOD can be seen as an elaboration of the ideas in the Swiss cheese model. The AcciMap is a method to develop a map of an accident by means of the abstraction hierarchy. The original description can be found in Rasmussen,... 

A preliminary assessment is used to identify those accidents caused by the HOF. Once these accidents have been identified, a detailed analysis was carried with HOF action taxonomy. Accidents were classified according to their major root causes, after reading accidental reports from EMARS. Table 1 illustrates the factors used for the accidental classification. In the first column, plant s operational conditions are listed and in subsequent columns HOF are highlighted. 

Technique of operations review (TOR) was developed by D.A. Weaver of the American Society of Safety Engineers in the early 1970s [13]. In regard to safety, it seeks to highlight systemic causes for the occurrence of an adverse incident rather than assigning blame. Furthermore, the method allows management personnel and workers to work jointly to analyze workplace-related accidents, incidents, and failures. Thus, TOR may simply be described as a hands-on analytical method to highlight the root system causes of an operation failure [13,14]. 

Root causes are the most basic cause of an accident/incident, i.e. a lack of adequate management control resulting in deviations and contributing factors. Stop rules have to be applied in the investigation into the accident sequence in order to avoid the garden-of-Eden problem where we look for accident causes far away from the accident site in time and space (Rasmussen, 1993). 

Nuclear power has achieved an excellent safety record. Exceptions are the accidents at Three Mile Island in 1979 and at Chernobyl in 1986. In the United States, safety can be attributed in part to the strict regulation provided by the Nuclear Regulatory Commission, which reviews proposed reactor designs, processes appHcations forUcenses to constmct and operate plants, and provides surveillance of all safety-related activities of a utiUty. The utiUties seek continued improvement in capabiUty, use procedures extensively, and analy2e any plant incidents for their root causes. Similar programs intended to ensure reactor safety are in place in other countries. 

In the shorter case studies, only the immediate causes of the errors are described. However, the more extended examples in the latter part of the appendix illustrate two important points about accident causation. First, the precondihons for errors are often created by incorrect policies in areas such as training, procedures, systems of work, communications, or design. These "root causes" underlie many of the direct causes of errors which are described in this section. Second, the more comprehensive examples illustrate the fact that incidents almost always involve more than one cause. These issues will... 

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. 

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. 

When the diagram is complete, the analyst proceeds through it to identify sets of events that were critical in the accident sequence. These critical events are then subjected to a further causal analysis using other techniques such as root cause coding, described below in Section 6.8.4. 

The first case study describes the application of the sequentially timed event plotting (STEP) technique to the incident investigation of a hydrocarbon leak accident. Following the analysis of the event sequence using STEP, the critical event causes are then analyzed using the root cause tree. 

Root Causes The combinations of conditions or factors that imderlie accidents or incidents. 

Accidents in industry occur for many reasons. A few of which can be attributed to mechanical failure, operational error (human error), and process upset, and design error. In order to understand tlie root cause of an accident, system safety appraaches have been put to use. 

When organizations focus on the root causes of worker injuries, it is helpful to analyze the manner in which workplace fatalities occur (see Figure 1-4). Although the emphasis of this book is the prevention of chemical-related accidents, the data in Figure 1-4 show that safety programs need to include training to prevent injuries resulting from transportation, assaults, mechanical and chemical exposures, and fires and explosions. 

Scenario A description of the events that result in an accident or incident. The description should contain information relevant to defining the root causes. 

An EPA-OSHA accident investigation at Napp Technologies Inc. in Lodi, New Jersey, developed the root causes and recommendations to address the root causes. Describe the accident, and develop layered recommendations for this specific accident. See http // www.epa.gov/ceppo/pubs/lodiintr.htm. 

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