ASSESSMENT METHODS FOR
GRADE CROSSING REGULATIONS
Ludwig Benner, Jr. and Jeffrey Chapman
regulation assessment practices are a mess and awash in controversy. A national
safety issue of major importance is the present inability of reasonable,
dedicated, conscientious and informed individuals to find a convincing and
harmonious way to resolve controversies about safety regulations, such as the
“stop” requirement for certain vehicles at grade crossings. Far too
much safety regulation is driven by seat of the pants opinions, without clearly
defined safety performance goals. Serious ethical considerations are also
purpose of this paper is to examine this issue, reasons it exists, and possible
actions to resolve it. A proposed change in a Federal rail—highway grade
crossing regulation, a study to assess the proposed change, and another study
assessing the assessment study are used to illustrate the problems and
alternative approaches available now. Continuing existence of this issue is
attributed to four interacting failures. Technical and managerial actions and
insights into alternatives that could bring about improved safety regulation
assessment capabilities and safety performance are discussed.
paper is written for presentation in January, 1987. Over four years ago, an
Advanced Notice of Proposed Rule Making was published in the Federal Register
by the Federal Highway Administration (FHWA) of the U. S. Department of
Transportation, asking the public for data or information about grade crossing
The information was requested to help FHWA decide whether or not to change a
mandatory “stop” regulation applying to certain vehicles at
rail—highway grade crossings. The response was quite underwhelming,
considering the long history of such accidents - and inadequate to support a
decision to change or retain the “stop” regulation.
that its decision involved controversy, the FHWA contracted for a study
“designed to determine the difference between the potential consequences
of requiring and not requiring certain vehicles to stop at [rail/highway]
crossings with active warning devices.
The study contained 12 diverse conclusions. It concluded, for example, that in
essence there would be a net decrease in train—involved accidents. It
also estimated the “excess annual expenditures” attributable to
requiring vehicles to stop at crossings with active devices when not activated
amounted to about $14 million. A conclusion about the expected reduction in
accident loses to offset these costs was not included among these Conclusions.
Several of the main conclusions were actually restatements of data, and at
least two contained obviously speculative or intuitive assertions. The
trade—offs developed in the study were not presented in a readily
assimilable form, and
our knowledge were not required to be so presented. However, the study is very
valuable for a discussion of the controversy about the assessment.
the study was completed, the FHWA let another contract to do an assessment of
the first study, in part because of controversy which the first study had
generated, as we understood the situation. The second study, concluding that
the first should not be relied on as the basis for rule-making, apparently
generated still more controversy.
For convenience, the first study will be called Study 1 and the other Study 2.
assessment studies, and two different conclusions! More controversy.
ISSUE: CONTINUING CONTROVERSY
is not confined to the persons who did the studies, or attending the
presentation of this paper. Irrefutable evidence of continuing disagreement is
found in the variations in the State “stop” safety regulations
adopted by state officials. Same states continue to require stops at grade
crossings; others do not. Which “safety” regulation is the
“best” and what does “best” mean?. The disagreement and
controversy has existed for a long time, and a consensus or even a pathway to a
consensus to resolve the differences is not in sight. It is this issue —
the continuing disagreement and lack of a pathway to its resolution that needs
to be addressed and resolved. The differences within the Studies are only
reflections of this deeper issue. Current safety regulation assessment
practices are a mess.
OF RAIL-HIGHWAY GRADE CROSSING
ANALYSIS AND ASSESSMENT PROBLEMS
in requirements among jurisdictions
about which is best requirement
now required to evaluate opinions
agreed proofs to resolve disagreements
has there been no clear pathway leading to harmonious and convincing resolution
of these differences about assessing a safety regulation? The reasons suggested
by over 18 years of inquiry into related safety problems can be observed in the
two studies. To present those reasons, some background will
research and analysis of the regulatory assessment issues and technology has
not addressed the underlying assumptions and concepts on which assessments are
based. Thus, little information about technical or managerial assessment
choices and their significance is available. Interest in risk analysis and risk
acceptance as an approach to regulatory assessment is growing, and the state of
the art is advancing, but this has not produced the needed harmonious pathway
to resolution of differences. For reasons that will be shown, it suffers from
similar difficulties. The bottom line is that there is no technical pathway to
support a consensus on assessments.
lack of agreed technical safety proofs leaves the resolution of assessment
differences to an adversarial debate, where debating skills rather than
technical proofs are most decisive to the “jury” of observers. This
is true not only of our legal processes, but of our regulatory processes. Is
this an acceptable way to settle issues dealing with the life and death of
people and environmental risks, and substantial economic costs?
think not, and therefore would like to examine the continuing assessment
controversy involved in greater detail, using the grade—crossing stop
regulation to illustrate the issues.
DOES THE ISSUE EXIST?
two studies provide useful insights. Neither study described the research
methodology selection decision or the selection criteria on which the work was
based. In retrospect, both should have, for reasons that will be apparent
shortly. Nevertheless, Study 1 is particularly valuable for the insights it
provides into the issues reported in Study 2, and Study 2 provides a
springboard to raise the issues.
assumptions in Study 1 provide a starting point for our examination. As is
typical of regulatory assessment studies, Study 1 contained many
and relied on them for its conclusions. These assumptions were apparently made
for a variety of reasons, including
of the “conventional wisdom” in the field.
of previously defined criteria for assessment.
of the accident phenomenon.
of accident data.
imposed by the analytical methodology used.
toleration by the assessment methodology used.
assumptions reflected uncritical acceptance of what is probably best termed the
“conventional wisdom” in the field - of the “everybody knows
that....” variety. For example, the first sentence in the introduction of
Study 1 begins with such an assumption, which leads it inexorably down what
observations of literally thousands of accidents show is a misdirected
regulatory assessment path. It asserts that “collisions between trains
and vehicles transporting either hazardous materials ... have potential for
catastrophic consequences.” Thus, Study 1 begins by assuming “the
is not supportable with facts about rail—highway grade crossing accident
consequences or hazardous materials accidents in general. Only a few types of
hazmat shipments truly have that potential, and any regulation assessment must
take these variations into account in its problem statement.
second assumption is related to the objective of the “stop”
regulation. The objective had to be assumed for the assessment study because no
record of its original safety goals or objectives and the trade—offs in
the regulation decision had been documented and kept with the regulatory
history. Therefore, Study 1 ‘s authors were compelled to assume the
criteria and trade—offs against which their assessment was made. (Study
1, p 14)
third type of assumption reflects perceptions of the nature of the accident
phenomena. In Study 1, these assumptions were extremely subtle, and likely to
go unnoticed by most readers who have not been sensitized to the issues. For
example, it is assumed that the types of accidents selected covered the full
range of accidents that might be affected by the present regulations.
Additionally, it is assumed that the recorded attributes in the accident cases
used by the study could reflect the full range of accidents influenced by the
“stop” regulation. Further it assumed that the accidents could be
adequately described and classified for analysis by a very small number of
attributes, such as train struck truck accidents, or vice versa, contrary to
numerous research findings.,
about accident data were also pivotal to the outcome of Study 1. It went to
great lengths to “validate” the accident data before it was used.
However, close examination of the validation process disclosed that it
validated data for consistency of the selected attributes or
“characteristics” with the case selection criteria for accident
types, and assumed the attributes in the surviving records were properly
recorded and trustworthy, despite a dropout rate of over 60% for some of the
records. It also assumed uncritically the data’s fidelity with respect to
the processes constituting the accident phenomena.
both these assumptions satisfied the methodology selected for the assessment.
While Study 1 highlighted data inadequacies, its complaints about the accident
records flowed from criteria that had to be met to satisfy the assessment
methodology, rather than the accident risks to be controlled. The methodology
selected for Study 1 provided no technical method for validating the fidelity
of the data to the accident phenomena — only their representativeness
relative to each other.
implicit assumptions relate to accommodation of changes. Study 1 used data from
a 9 year time period. Many changes occurred during that period, including
numerous programs to reduce the number of grade crossings, better training of
drivers, the cooperative Life—Saver programs, and increasing use of
double bottoms, among others. The use of the data in the study assumed that
these changes would somehow be accommodated by the assessment methodology used.
That methodology provides no way to predictively assess the effects of these
changes on the accident attributes; such predictions are better performed with
different data and analyses.
is noteworthy that the study turned to process—oriented analysis
methodology in Chapter 6 after the assessment problems and vagaries of the
statistical data analyses were observed. That decision indicates the low value
of the attribute data for assessment purposes. That low value, in turn, raises
doubts about the value of the effort to acquire it, and suggests that the data
acquisition effort, and the resources expended to acquire it, were wasted.
2 was an evaluation of the evaluation - again, not an uncommon practice. It
addressed primarily issues relating to the merits of the assessment and its
methodology and practices, rather than the merits of the regulation being
assessed. Study 2 was critical of the conclusions reached in Study 1, and
concluded that the agency should not base its rule making on its conclusions.
The report concluded that the Study 1 authors may have lacked a sufficient
understanding of the accident phenomenon to ... satisfy the study objectives. A
major concern was the well known logic fallacy of assumptions which were
“poisoning the wells”
essence, Study 2 spoke to the assessment issues from a different view than
Study 1. Study 1 uncritically adopted an “attribute-based”
assessment methodology and manipulated “validated” data with
statistical tests to reach certain conclusions about the regulations. Study 2,
using primarily an event— based process approach, criticized the
assessment methodology, assumptions, the use of the data, and the conclusions.
unresolved assessment differences represent symptoms of what is truly a
national safety issue of major importance. That issue is the continuing
inability of reasonable, dedicated, conscientious and informed individuals to
find a way to resolve controversies about the most desirable safety action in
this and many other comparable safety problem areas. This conclusion about its
importance results from being a participant in many such controversies, and
observing the players, roles and actions, interests and outcomes in those
experiences, including continuing losses from inaction or misdirected action.
about safety action results has grave consequences. It breeds delay, it breeds
misdirection or the wrong action, and it breeds excuses for no action at all.
It can result in adversarial relationships among the very people who need to
work together to control the risks. Is that acceptable where lives and societal
resources are at stake? To me, the situation is intolerable.
resolve the controversy issue, we need to examine it in terms of the goals of
science: we need to understand and be able to predict it, and then control it.
does controversy exist? My observations indicate that the controversy flows
from interacting failures in current safety regulation formulation and
DIFFERENT VIEW OF THE PROBLEM
to demand regulatory objectives
to acknowledge nature of accidents
to use investigators properly
to recognize consequences of regulation assessment methodology selection decision
examine each of these failures in detail.
1: Failure to demand safety I
for safety regulations.
of the most significant and valuable contributions of Study 1 was the reported
lack of documentation describing why the safety regulation in question was
established in the first place. There is little doubt that the grade-crossing
stop regulation was established in the name of “improved safety.”
How much more safety was expected, and how was that safety improvement to be
weighed against offsetting trade—offs? My experience, with few
exceptions, has been that such an estimate of the expected safety improvement
has rarely been demanded or offered. The grade-crossing regulation is no an
is that significant? It means that no basis for assessing the success of the
regulation has been possible to measure the success of the regulation over the
years. It also means anyone can now offer any objective they wish to introduce
into the controversy as an assessment criterion. Is it any wonder controversy
objectives can be developed and used, from a technical perspective. In some
instances, estimates were provided, such as the railroad head shield and
coupler retrofit regulatory initiatives. In the Federal Railroad
Administration’ s regulatory docket HM 144, the safety objectives were
specified as a part of the rule making, but only after the accident process was
defined and demonstrated - with motion pictures of reproduced accidents. The
accidents could be reproduced, which means they were adequately understood and
objectives were originally formulated to demonstrate the consequences of
delayed regulatory action, but it was found they could serve as safety
objectives for the rule. However, it must be recognized that they were
introduced originally as a peripheral issue, forced into a predominantly
economic framework. The safety objectives were not demanded as a routine part
of the regulation development process. It should be noted that the objectives
were used to track the success of the regulations.
absence of a statement of safety objectives for the original stopping
regulation precludes a direct comparison between the intended safety
performance and the actual safety performance achieved by the regulation. Thus,
the authors were forced to do the study without explicit objectives against
which to measure the current or changed regulation’ s success. In other
words, they had no assessment criteria to determine if the present regulation
was achieving its intended safety performance.
don’t we routinely have safety objectives for regulations? My research
and subsequent observations indicate this failure flows from two other
analysis of accident investigations and the data they produce has disclosed
that two major kinds of accident data are gathered and used as a basis for
safety and regulatory action:
data is data describing the characteristics of an accident. These
characteristics usually are static characteristics. Example:
“grade-crossing” is used as an attribute of some accidents. Other
attributes included train— involved, did—not—stop, unknown,
less-then 10 mi/h, etc. (Study 1, p 44) Careful examination discloses that
there are no consistent forms or contents of the attributes. As practiced,
attributes can be anything the creator desires to propose. Process data is data
describing interactions among system elements that produce an outcome. Process
data is most often described in narrative form or modeled with flow chart type
descriptions. It is constructed of dynamic events.
- HIGHWAY HAZMAT GRADE CROSSING ACCIDENTS
AND EVALUATION CHOICES
o Accident factors
Sequential logic tests
between the two kinds of data need to be recognized to understand the
controversy issue. Attribute data can be any “factor” or
characteristic of an accident that anyone wishes to record; relationships among
attributes are established by statistical analysis. Attributes are usually
conclusions, high on S.I.Hayakawa’s ladder of abstraction, introducing
ambiguities that mask uncertainties.
Process data is interdependent; process data must be in a descriptive form that
will accommodate spatial and temporal relationships and satisfy sequential
logic tests. Attribute data is predominantly static; process data is dynamic.
Attribute data is abstract; process data must be concrete. Attribute data lends
itself to counts and their mathematical manipulation or testing; process data
lends itself to interactive change analyses. Attribute-based analyses require
validation by future occurrences of the same attributes; event-based process
analyses are validated by observing operations for the occurrence of event sets.
2: Failure to acknowledge
many assumptions in Study 1 provide an instructive example of the problems
created by using attribute data describing static abstractions about accidents.
During the accident validation process in a very familiar area —hazardous
materials truck grade-crossing accidents — only 161 of 440 reported
accidents (less than 37%) could be “verified” as acceptable for the
study. A close look at the verification process discloses it only verified that
the vehicle was a truck or tractor—trailer while simultaneously
indicating that hazardous materials were being transported by either the
highway user or both the highway user and/or the railroad. In other words, the
validation required only that the attributes be consistently reported. IT DID
NOT VALIDATE THAT THE DATA ACCURATELY DESCRIBED THE ACCIDENT PHENOMENA IN A
PROCESS SENSE. The 63+% dropout rate, based on a relatively simple reporting
decision by the accident investigators and reporting organizations, raises
grave doubts about the quality of the remaining data about the accident
characteristics the study authors were compelled to use, and even graver doubts
about the validity as process descriptors.
more subtle problem with the attribute-based approach is the inherent adoption
of the “single cause” perception of the accident phenomena. This
results from the treatment of attributes in isolation from other elements of
the accident phenomena, to distinguish the independent from the dependent
variables. Tables in Study 1 have extensive listings of individual attributes
and break them down into percentages from which conclusions are drawn. This
quickly and almost inexorably leads to the “single fix”
presentation of data and mindset. For example, if we show you the relative
proportion of driver actions related to accidents in a pie chart, what is your
initial reaction? Most frequently, do something about the “did not
this tell us that the stop regulation is ineffective, or being ignored, or
what? Obviously, we need more data. Don’ t we always need more data when
we start trying to interpret attribute data to determine what action to take?
2 commented on some of the strained interpretations of the attribute data and
the conclusions drawn from that data. It is revealing that Study 1 shifts away
from the attribute data and toward process data in Chapter 6, toward the end of
3: The failure to use I
accident investigators properly.
domination of the attribute-based approach for regulatory assessments also
leads to misuse of accident investigation and reporting resources. The use of
only 161 of 440 reported accidents (less than 37%) that could be
“verified” as acceptable suggests a shameful waste of effort. From
previous research, the reasons this occurs are clear.
types of accident investigation and reporting approaches drive the development
of accident data. Investigators function either as
gatherers, filling in forms to provide data for others to analyze and use, or
trying to understand the phenomenon they are investigating.
accident data (probably 99% in one author’s experience) is generated in
support of (a). For forms preparation, replicability of the entries if of far
greater concern than replicability of the accident phenomenon.
Yet understanding, prediction and control of the accident phenomena is
required to produce effective safety regulation and assessment. Despite this,
only the MORT accident investigation program routinely makes an effort to
satisfy the latter need, but relies heavily on abstractions in checklists.
Same governmental agencies (NTSB, DOT) do (b) type investigations in limited
numbers, but usually in major accidents. A new book about accident
investigation takes the issue a step further (10)
significance of the extensive use of data gatherers is that the approach
de-emphasizes the demand to understand the phenomena, so they can be controlled
promptly. This approach poses ethical questions, too: it is a disguised form of
testing on the public, an issue that the late Henry Wakeland expressed so well
at the NTSB in the late 1960s. Yet it is still widely practiced.
bottom line is that most investigation time is wasted.
4: The failure to acknowledge the
of assessment methodology decisions
influencing each of the above failures is the decision about the analysis and
assessment methodology selected for safety issues. The authors initially
selected the popular analysis methodology currently driven by statistical
inference technology, and inductive or deductive logic. Is this important?
research has shown that the selection of statistical inference techniques using
currently available accident data has grave consequences for the
of regulatory actions
of investigation programs
analyses and assessments that can be produced
of safety performance
issues have been reported elsewhere in detail. (6),
Note that the Judicial sector is awakening to the problem, too.(11) The reason
for highlighting them again here is that we are convinced — without
reservation —-that the methodology selection decisions contribute
directly to the controversies about proper regulatory safety action, and our
inability to resolve these controversies.
THE ASSESSMENT ISSUES
12 years, at the National Transportation Safety Board, one of the authors was
faced with producing recommendations from single hazmat accidents, because the
types of major accidents investigated were so infrequent that it was not
possible to build a database to accumulate enough cases to draw statistical
inferences or analyze trends. In other words, we just couldn’t wait to
build a data base from more Bhopals or Texas Citys. Also, it was considered
unethical to adopt a methodology that required more major accidents to occur
before our premises could be “proven.” Therefore, a search for
alternative approaches was initiated. Since leaving the Board, additional
research and applications have provided even clearer insights into these
retrospect, existing methodological alternatives rest on two fundamental
approaches. One is based on accident attributes and the other on accident
events descriptions. Both were tried, to perform various functions, including
accident investigations, safety problem definition, development of safety
action recommendations, assessment of safety programs, assessment of
regulations and others. Differences became clear during these applications. How
are they different and what do those differences mean to the assessment
consequences resulting from the selection of either approach were found to be
of the major consequences was the difference is in the rigor of the
“building blocks” that are used in the tasks. Attribute-based work
uses “factors” which does not disqualify anything related to an
accident from consideration or analysis. Event-based work, on the other hand,
uses “events” which, while not defined with precision for many
years, were disciplined by the need to satisfy at least temporal and spatial
sequential logic tests. In applications, the main problem with
“factors” has been and still is their ambiguity, and the delays
encountered in determining relevance. However, and here is the main problem,
since any input could and would be entertained with statistical analysis
methods, the data screening for relevance did not occur until substantial data
collection effort was expended. As a result, a factor
gain a life of its own before its validity was disproved using conventional
second result was that the huge numbers of hypotheses and quantities of data
overloaded the analysis systems. That meant analysts had to be selective about
the data used, which created cascading problems and opportunities for
“second guessing.” Event-based work, on the other hand, dealt with
a different type of data which was organized by the end of the investigation.
You knew what part of the accident process you understood, and what you
didn’t understand. The surviving data had also been tested for relevance
by logically determining if the description of the accident process was
feasible and fit all the “evidence” left by that process.
Controversy was easy to narrow and resolve with further investigation, with
simulations or testing, or even with structured and disciplined speculations by
major technical consequence was the level of abstraction that became involved.
The greater the degree of abstraction tolerated, the less the discipline
exerted on investigators. Attribute-based work was observed to resolve
ambiguities by moving UP Hayakawa’ s ladder of abstraction, toward
restatement of factors in more general terms to overcome the ambiguities. Thus
it is easy to report “human error” as an accident cause with
attribute based investigations, but almost impossible to do so with event-based
consequence was that the more abstract the “factor” the more
impossible it became to use it as a basis for daily control of the risk. For
example, human error is an abstraction that must be restated in terms that are
more concrete before an effective control action can be determined or
recommended. Event-based work, on the other hand, tended to move down the
ladder of abstraction toward more and more concrete descriptions of the
deviation from expected actions. In other words, attribute-based work tended to
overcome ambiguity and controversy by moving toward more generalized
descriptions -increasing the potential for controversy, while event-based work
tended to become more concrete, decreasing the area for disagreement.
major consequence was the credibility of the results of the “truth”
tests applied to the accident data. By truth tests, we mean validating the role
of a “factor” vs. an “event” in the accident. Without
going into arguments about the stochastic vs. deterministic nature of
phenomena, let us point out that the attribute work (driven by stochastic
views) tested data of any kind with count or measurement-oriented statistical
tests, while event-based work tested data with precede/follow interactions and
sequential logic tests.
the significance lies in the discovery that attribute-based data was rarely
expressed conclusively, while event-based methodological choices led to
descriptions that could be demonstrated and credible to reasonable observers.
In addition, event-based choices provided for the real-time definition of
accident process unknowns, and thus defined the remaining data needs during an
investigation, rather than months or years later when aggregated data from more
accidents was analyzed. Thus, the technical testing did not require additional
accidents to occur to determine data validity or additional data needs,
overcoming a major ethical problem.
technical benefit was that the event sequencing provided an orderly method for
identifying and evaluating event control actions to produce a much larger
choice of control actions; the accident process could be controlled at any
point in the process by introducing a change in one of the events or an event
technical benefit was the ability to observe real time operations to determine
whether accident events or event sets were still present in the operations, and
to assess the success of controls that had been implemented in controlling the
phenomenon. The difference is like being able to watch vehicle and train
behaviors at crossings to look for specific actions by each vehicle, vs.
sitting there waiting for an accident to happen so you could capture its
dwell time work introduced in Study 1 illustrates the ultimate need to try to
understand the accident process before acting, and is very commendable in that
respect. As this is written, the outcome of that technical work is not known,
but it is likely that it can contribute to resolution of controversy rather
than intensifying it. Because it moves down the ladder of abstraction toward a
more concrete process description, the new work will contribute to the more
definitive control of the accident process.
OF ANALYSIS METHODOLOGY SELECTION
- Regulate factor
- investigate to test
- accident investigators =
- analyze data to test for
analyze event sets for
- monitor trends
- control process
- investigate to understand
- accident investigators = hypothesis developers
- analyze events sets for
- monitor operations
IMPLICATIONS FOR REGULATION ASSESSMENT.
far, the technical implications of the alternative approaches have been
discussed. Of far greater significance to the issue are the managerial
implications of the alternative assessment methodologies. A shift toward
event-based analyses can provide regulatory, operational and scientific
managers new opportunities to overcome the failures cited above. From a
perspective, objectives for regulatory safety actions can be established
promptly by focusing on the specific events pairs or sets that are to be
controlled by the regulatory action. The regulation can be assessed by watching
future operations to see if those event pairs or sets have been eliminated or
controlled. The objectives can be defined and assessed in terms of the
exposure, frequency and consequence ranges, as illustrated by the HM 144 rule
that analysis, target safety performance objectives can be established by the
regulating organization, whether it be a governmental organization, industry
group setting standards, or individual organizations establishing safety
procedures. Thus we can move away from the ambiguities and potential for
controversy introduced by the attribute-based approaches, toward an approach
that fair-minded persons can understand and consider reasonable.
second benefit is the opportunity for redirection and reorganization of the
data acquisition efforts required to support safety actions and assessments.
The redirection would include
restatement of the grade-crossing accident investigation mission, objectives
and approaches to produce accident process descriptions.
of a plan for coordination and conduct of those investigations and assessments
that are undertaken,
in the investigative and assessment methodologies,
of the accumulation and analyses of the investigation work products, and
feedback and assessment schemes after actions are taken
new mission of accident data acquisition and assessments could be to
understand, predict and control accident processes to achieve a reasonable and
predetermined level of safety performance in the operation of interest, such as
highway operations at grade crossings. The new mission should acknowledge that
both pre-mishap assessment and ongoing assessments of control actions such as
regulations are needed.
new objectives could be to ensure thorough understanding of the accident
process, and presentation of that understanding in a new descriptive format to
which everyone could contribute harmoniously and in which the uncertainties
could be described in persuasive ways. Event-based displays have been found to
achieve both objectives.
event—based displays have also been used as a vehicle to coordinate the
contributions and facilitate the acquisition of data to fill gaps in accident
understanding. The primary benefit has been the ability of event-based work to
define unknowns on which attention should be focused to reach a common
understanding of an accident process. This has permitted parties with widely
divergent interests to work together toward a common goal — understanding
the accidents, and how to control them, from which informed control actions can
be undertaken with minimal controversy. The experience has also included
participation in investigations where a thorough understanding of an accident
prompted unilateral action by several parties. That understanding has also
provided the basis for subsequent monitoring of the their effectiveness.
these experiences has been an awareness of the need to reconsider assessment
methodologies, and also a way to do the assessment better. Time and again, we
have observed a lack of confidence in “the numbers” and seen a
process description accepted without dispute if it looks plausible. An
unequivocal and complete description of an accident has been found to be a
persuasive motivator of action, when presented candidly to show all the knows
need is a way to aggregate data, but for reasons that differ from current
practices. Accident data needs to be aggregated in a way that permits the
widest possible dissemination of each accident description as soon as we know
what happened. Here again, it has been found that event-based descriptions of
mishaps, properly done, enable both operational and research actions to be take
on individual accident cases. Unfortunately, aggregation of data today is aimed
primarily at supporting hypothesis testing. We really need to take a new look
at what we are doing, why we are doing it that way, and what the payout is.
need is to change our perspectives about what we investigate. Attribute-based
approaches essentially demand that we gather data about significant accidents
that have occurred. Significant means above some threshold loss value, usually.
With event-based approaches, it has been found that lesser mishaps and even
near misses in which the learning potential is not distorted by the need to
determine who pays for the loss, are much more valuable to understanding mishap
processes than accidents where the witnesses are gone, or the things are
demolished during the mishap. Further, the experiences can be related in a
non—threatening way to current operations and work processes.
Finally, event-based approaches provide the basis for future assessment of current
safety actions, in that the structure of the mishap descriptions permits real
time monitoring of current activities and how they are performed. Thus,
high-risk event sets can be pre-investigated, that is addressed before serious
mishaps occur in a constructive rather than a punitive way.
The technology to support these changes is in place. However, administrative and
scientific managers’ determination to apply it are not in place. It seems
a safe prediction that, as the potential for reducing controversy, assessing
safety and economic effectiveness and the ethical considerations become more
widely recognized, we will begin to see both administrative and scientific
managers’ demands of investigators and assessment analysts changing
rapidly. It was a costly experience, but we commend the history of the
resolution of the tank car head—shield controversy
to you as must reading if you really want to find out how to begin resolving
controversy about regulatory actions and their assessment.
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