ACCIDENT MODELS: HOW UNDERLYING DIFFERENCES
AFFECT WORKPLACE SAFETY
By Ludwig Benner, .Jr.
University of Southern California,
In our efforts to discover and correct workplace safety
and health problems, we often wait too long and then fix the wrong problems.
The reasons: inadequate intellectual concepts of the phenomenon of accidental
harm lead to use of inappropriate investigation and analysis tools, which
misdirect the search for data that define our safety and health problems and
their solutions. Borrowed technology from other disciplines is inadequate for
future safety improvement tasks. This paper explores underlying accident
concepts and investigative practices) how they affect workplace safety, and
what is happening to overcome some intellectual shortcomings.
To illustrate this issue, differing conceptual models of
the accident phenomenon currently driving safety problem identification in 17 U. S. government agencies were
examined. From this examination, criteria for judging the merit of alternative
accident models in occupational safety and health programs were defined. The
criteria were then used to rate each model. The models' impact on the
investigative methodologies resulting were examined next, and criteria for
judging the methodologies were defined. Applications of the highest rated
models and methodology were then compared with existing practice to determine
what improvements might be expected. Based on the findings, further development
and applications efforts are suggested.
In 1982 an estimated 11,100 fatal and 1,900,000 disabling
injuries in workplaces were experienced in the United States(1). In 1970, amid
much fanfare, national legislation was adopted in the U.S. to stop this carnage
in workplaces, and much action has been taken. Yet since then, almost 2% of our
working population suffers serious workplace injury each year. For each
of these workers, the safety control system failed. Why did it fail?
THE SAFETY PROBLEM DISCOVERY AND DEFINITION ISSUES
Compelling evidence that
points to the reason is accumulating from my inquiries into a wide range of
safety matters. This evidence indicates that these failings flow from
intellectual shortcomings in the safety problem discovery and definition
processes, rather than from other origins. Each new examination of that process
I undertake seems to add greater weight to that conclusion. With each new
inquiry, specific intellectual inadequacies seem to become clearer. Apparently
my concern is shared by others.(2,31,32) My work indicates that this matter
deserves urgent attention. It is gratifying to be able to discuss the issue at
this seminar, and I thank the sponsors for this opportunity.
The information in this paper reflects observations in
many inquiries into this safety problem definition and response issue. The
inquiries were conducted both as an employee of the National Transportation
Safety Board in accident investigations, and during personal research in
support of my teaching activities. The issue was examined from many
individuals " perspectives. For example, it was examined from the workers
viewpoint. An early inquiry related to defining tasks facing emergency response
workers dealing with hazardous materials.(3) In emergency situations, what
techniques should they use to identify and define the danger?(4) How are these
workers expected to interpret emergency response instructions(5) How does one
define and measure their effectiveness in accident emergencies(6)?
. . .
(Example of intellectual
confusion from paper)
APPENDIX 1: MEANING OF "CAUSE" IN ACCIDENT INVESTIGATION
What do you mean by the word "cause " as you use it in accident investigations?
which leads to an outcome or result.
2. the primary
underlying reason for an act or event.
that takes the actions of an object or being and is the reason for the second
4. a word used
to show the relationship of an action to an individual or thing; means made or
associated with a happening; it is responsible for the happening .
5. an effort by
individuals or groups to achieve a desired end.
event which leads to the resultant occurrence of another event.
influence that determine a particular outcome.
event or combination of events that determine the outcome of a
condition that leads to an occurrence.
10. something that
results in an effect or another phenomenon.
11. a state,
situation, occurrence, event which leads to, is primarily conducive to a second
state, situation, etc.(etc) which is partially responsible for a second
occurrence, event (etc).
12. a reason for a
13. a determination
of what happened.
14. an event, state,
action or reason that leads to a fact.
15. a root source by
which a resultant event can be explained.
16. The cause is-the
event or set of events producing the accident. l believe cause is the same as
17. the reason that
an event occurred; the driving force or motivation.
that brings about an effort or result.
19 any event,
circumstance or condition or any combination of these that brings about or
helps bring about a result. (Webster and l agree)
20. the sum effect of
various factors which, in combination, precipitate the occurrence of an event.
accident, except for 2% that are classified as acts of nature, is caused by the
unsafe behavior of an individual, or an unsafe mechanical or environmental
condition, or both. The investigator must identify and describe the causes, as
failure to do so negates the entire investigation effort.
22. a reason for the
state of things.
producing an effect or result; a person or thing acting voluntarily or
involuntarily as the agent that brings about an effect or result.
24. the reason for an
event to occur.
25. factors, as those
singularly or in combination, that bring about a result (usually a known
result); an entity that is the agent of bringing something about .
26. can be an action
of a person; can be a failure on the part of a mechanism.
27. the item that
allows or drives the event to occur.
28. a factor must be logically
related " traceable to the result. Must be a factor without which the result,
the, accident, would not have occurred, or would not have the same way with the
29. an event(s)
which deviated from the usual or accepted operating procedures.
30. an event which if
changed would have interrupted the chain of events and prevented the mishap.
31. what starts an
imbalance in a balanced system.
that if not present or active would have stopped or
possibly stopped (or altered) the outcome of a
33. a summary of what
happened; let management pick out what they believe to be the cause.
34. acts or
conditions most closely associated with the injurious event which make the
injurious event irreversible.
35. the events,
situations or circumstances which lead to an accident or permit the accident to
36. an off "normal
action or event without which the accident would or could not have happened.
which directly contributes to an event called an accident.
38. an energy input
that produces or contributes to the energy of the accident.
39. something that
helps tell me "why " and accident occurred.
40. that which triggers
an action or that which is a motivating force in the
41. a factor which,
when it is present alone or in the proper combination with other such factors,
results in the occurrence of the accident.
42. one of the
verifiable circumstances contributing to the accident; the source of such being
human, environmental, mechanical or whatever.
43. an event
that produces a 2nd event.
44. a factor
which led to or formed the conditions necessary for the accident to happen .
46. those events and
factors which together brought on the accident.
47. the factors which
contributed to or the deficiency in the system to control the flow of energy or
prevention of accidents.
48. all events and
factors that combined to result in an accident; these may range from general
systemic oversights to specific events immediately preceding the accident
49. the failure
or failures that led to or created the accident.
chain "of-events or things that occurred that permitted an incident to occur .
51. event or
condition sufficient to produce an unwanted result.
52. the cause in a
53. a condition which
effects an event with either wanted or unwanted results.
group or system actions, conditions, deficiencies, failures, changes, errors
and responses which contribute to the initiation of potential or accident
Source: Ludwig Benner, Jr. Univ. of Southern California 05-19-83
5 groups: Replies/populations:5/5: l5/l6: 15/15:
nouns counted = 88 in 54 replies