Oversight and Risk Tree

Emerging concepts of system analysis, accident causation, human factors, error reduction, and measurement of safety performance strongly suggest the practicality of developing a higher order of control over hazards (than currently exists). 

Johnson, who had recently retired as general manager of the National Safety Council, advanced the idea that the application of controls and resources by the management of occupational safety and health programs could be categorized into five basic levels  

Less than minimal compliance with regulations and codes 

Basic Guide to System Safety, by Jefirey W. Vincoli Copyright 2006 John Wiley Sons, Inc. 

Advanced safety programs exemplified by those currently found in leading companies 

The symbols used on the MORT chart are basically those used for other analytical trees (Chapter 10) and fault tree analysis (Chapter 15). They include the rectangle as the general event symbol, the circle as the base event symbol, the diamond as an undeveloped terminal event, the and gate, the or gate, and the ellipse as a constraint symbol (Rgs. 18-1 and 18-2). 

In addition, Bill Johnson used a scroll as a normally expected event and an oval as a satisfactory event. The normally expected event distinguishes events that are typically a part of any system, such as change and normal variability. The satisfactory event describes events that may be accident causal factors but are a necessary part of the operation, like functional (part of the system) people or objects in the energy channel. Also, in addition to using the traditional transfer symbol (a triangle), the MORT chart includes capital letters as drafting breaks and small ellipses as risk transfers (Fig. 18-3). 

Risk transfers are found in two places. They are found next to undeveloped terminal events, and they are found near the top of the chart as assumed risks. The implied logic is that barriers, controls, or evasive actions are not possible or practical in those areas where there are undeveloped terminal events. If activity is continued under these circumstances, then some risk is assumed or accepted. The small assumed risk transfers are used to denote a transfer up to the small ovals under the assumed risk portion of the MORT chart. 

Abbreviations used on the MORT chart include LTA, the most frequently used, which stands for less than adequate DN for did not FT for failed to HAP for hazard analysis process JSA for job safety analysis and finally CS R for code standards and regulations . 

System Safely for the 21 Century The Updated and Revised Edition of System Safety 2000, 1 Richard A. Stephans 

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MORT Management Oversight and Risk Tree analysis lohnson, 197.1... 

FIGURE 6.6. Management Oversight and Risk Tree (lohnson, 1980). 

A last reference here is the Guide to Use of the Management Oversight and Risk Tree (MORT). In the abstract for that publication, MORT is described as a comprehensive analytical procedure that provides a disciplined method for determining the systemic causes and contributing factors of accidents. This reference to performance errors is of particular interest. 

Guide to Use of the Management Oversight and Risk Tree (SSDC-I03). Washington DC U.S. Department of Energy, November 1994. 

These are but a few of them single event theory chain of events theory epidemiological models systems theory models multilinear events sequencing human factors models life change unit theory motivation-reward satisfaction models and the management oversight and risk tree model. 

The definition of an accident contained in the original literature on MORT management oversight and risk tree) indicated that an injury was preceded by sequences of planning and operational errors which (a) failed to... 

Most causation models have minimized less than adequate design and engineering concepts and outcomes as a source of causal factors for hazards-related incidents, with one significant exception. That exception is MORT—the management oversight and risk tree. Concepts on which MORT is based have influenced my thinking greatly, and I am indebted to all who worked on the creation and betterment of MORT. 

In this supporting discussion, the influence of system safety concepts will be evident, as will the concepts on which MORT (management oversight and risk tree) is based. 

This causation model puts a major focus on less than adequate management practices that impact on the operations system as a source from which causal factors derive. A borrowing of significance is taken from the Guidelines to Use of the Management Oversight and Risk Tree to emphasize focusing on the system ... 

The heart of the book is its presentation of Sequentially Timed Events Plotting (STEP). The accident investigation methodology presented relies on a new conceptual framework, building on system safety technology and the safety assurance systems of MORT (management oversight and risk tree). 

Or, assume that the causation model is to relate to the concepts on which the management oversight and risk tree is based (a) the system safety idea and (b) an understanding that causal factors may derive from workplace or work methods design. 

And it is appropriate to recognize that system safety concepts were foundational in the development of MORT (management oversight and risk tree). References to system concepts are frequent in Johnson s MORT Safety Assurance Systems and in other literature on MORT. 

In 1973 a revised management oversight and risk tree (MORT) manual was published by the AEC. Even though Johnson borrowed heavily from existing DOD and NASA programs, his MORT program bore little resemblance to programs based on MIL-STD-882 (Johnson 1973). 

Another major approach tends to be very different from other efforts described. The Department of Energy s approach is based on the management oversight and risk tree (MORT), a comprehensive, state-of-the-art program for safety management and system safety. 

Johnson, William G. 1973. MORT, The Marutgement Oversight and Risk Tree. 

Figure 10-2 Analytical trees. (Derived from the student workbook from the Management Oversight and Risk Tree Workshop presented for the Department of Energy by the System Safety Development Center.)...

The management oversight and risk tree (MORT) chart is a large, complex, negative tree (see Chapter 18). Even though the project evaluation tree (PET) is depicted as a positive tree, it is mentally converted and used as a fault tree for accident analysis applications (see Chapter 16). 

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