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- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 38
The differentiation and decision matrix risk assessment of
accident precursors and near-misses on construction sites
Qiang Chen, Weiwei Wu, and Xing Zhang
Abstract—Precursors and near misses are well of the precursors and near misses will give the potential
known for providing a major source of useful to control variability rather than by constraining it.
information for safety risk management. They are more Moreover, the investigation of precursors and near
frequent events than accidents and their causes may misses incidents can be used as a source of information
potentially result in an accident under slightly different for the construction of a structured methodological
circumstances. Despite the importance of this type of approach for decision-making. Information from
feedback, there is little knowledge on the characteristics precursors and near misses incidents investigations can
of precursors and near misses, and on the use of this also be important tools for improved risk
information in safety risk management. This paper communication.
Index Terms— Precursors, Near misses, Risk-based
focuses on differentiating the concepts of precursors
related and evaluating the risk of precursors, near evaluation, Decision matrix.
misses. First, precursors, near misses related concepts
I. Introduction
are reviewed and the relationships between the concepts
are presented. Furthermore, the importance of
Almost every year there is at least one
precursors and near misses to further improve safety
technological disaster that highlights the challenge
margins are emphasized. Eventually, risk-based
of managing technological risk. On February 1,
evaluation of precursors, near misses is performed and
2003, the space shuttle Columbia and her crew
the impacts of precursors, near misses on quantitative
were lost during reentry into the atmosphere. In the
risk estimates are emphasized. By describing the
summer of 2003, there was a blackout that left
precursors, near misses incidents with related
millions of people in the northeast United States
probabilities and consequences, proactive management
without electricity. On March 23, 2005, the
can be mobilized. Furthermore, a deeper understanding
explosions and fires at BP’s Texas City refinery
that killed 15 people and injured 170 [1]. Why
Manuscript is received May 8, 2012. This work is based
were the events that led to the accident not
on three relative research projects respectively funded by
recognized as harbingers? Why were risk reducing
the National Natural Science Foundation of China (Grant
steps not taken?
No. 51008073), the Natural Science Foundation of Jiangsu
A recent study by the US National Academy of
Province (Grant No. BK2011609) and the Transportation
Sciences, which brought together experts on risk,
Science Research Project of Jiangsu Province (Grant No.
engineers, practitioners, and policy makers from
2011Y14-2).
different industries, focused on the signals,
Qiang Chen is with the Institute of Construction and
conditions, events and sequences that preceded and
Real Estate, Southeast University, Nanjing 210096, PRC
led up to accidents, and stated that many
(e-mail: chenqiangjx@foxmail.com).
organizations had attempted to develop programs
Weiwei Wu is also with the Institute of Construction and
to identify and benefit from accident precursors [2].
Real Estate, Southeast University, Nanjing 210096, PRC
In this book, the author described the precursors
(e-mail: wuweiwei@seu.edu.cn).
strategies in aviation, the chemical industry, health
Xing Zhang is also with the Institute of Construction and
care, nuclear power and security operations. In
Real Estate, Southeast University, Nanjing 210096, PRC
addition to current practices, they also address
(e-mail: zhx@seu.edu.cn).
some areas for future research.
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Using accident precursors to predict and prevent industries, including the chemical and process,
accidents is not a new idea. In the nuclear industry, airline, rail, nuclear, and medical disciplines [10].
the U.S. Nuclear Regulatory Commission (NRC) A compilation of papers with a cross industry
started the Accident Precursors Sequence Program perspective is provided in Near misses Reporting
in 1979 [3]. Over 1,000 licensee event reports are as a Safety Tool [14]. The most detailed study of
submitted to the nuclear power plant (NPP) near misses management in the chemical industry
regulator, the NRC, each year. The Aviation Safety known to us is the thesis of Van der Schaaf [15].
Reporting System operated by the National Jones et al. provide an account of near misses
Aeronautics and Space Administration, have been management systems successfully applied in the
in existence for several decades. The offshore European chemical industries [16].
petroleum industry in Norway has also reported Some studies have investigated how data from
major hazard precursors to the authorities for a near misses should be used in safety management.
decade [4]. Renewed interest in precursors analysis However, each study tends to emphasize one of the
has shown that the evaluation of near misses is an following steps: identifying near misses, analyzing
interdisciplinary effort, fundamental within the life data and defining actions resulting from the
of an organization for reducing operational risks investigation of the events [17]. For example,
and enabling accident prevention [5]. There has Brazier, Reason, Van Der Schaaf and Kanse,
been notable work in the codifying and evaluation Renshaw and Wiggins, Dekker focused on the
of precursors data through utilization of Bayesian stage of identifying these events [13], [18][21].
analysis [6][10]. Pate-Cornell presents a Bier and Mosleh addressed the analysis of near
probabilistic approach to use precursors analysis to misses [7]. The study by Van Der Schaaf,
create “signals that action has to be taken ... to undertaken in the context of the chemical industry,
reduce the risks of failure as much as possible proposed a set of steps for the use of data from
within resource constraints [11].” Carroll near misses [22].
demonstrates the importance of knowledge This research focuses on differentiating the
management within organizations, so that concepts of precursors related and evaluating the
precursors can be effectively addressed as “signals risk of precursors, near misses. The first part of the
of possible problems” and “opportunities to enact paper briefly reviews some of the previous studies.
and improve organizational practices [12].” The remainder of the article is organized as
Phimister et al. not only observe the follows. In Section 2, the definitions of concepts
interdisciplinary nature of precursors analysis but precursors related are presented. Section 3,
also the fact that this practice is diffused across differentiate the concepts precursors related.
different industries [2]. Section 4, describes the importance of precursors
Near misses are well known for providing a and near misses to further improve safety margins.
major source of useful information for safety Section 5, risk-based evaluation of precursors and
management. The use of data from near misses in near misses is proposed. Section 6, emphasized the
safety management has been identified as an impact of precursors and near misses on
important practice in the prevention of accidents, quantitative risk estimates. Section 7, provides
especially in the areas of civil aviation, the conclusions.
generation of nuclear power, the chemical industry
II. Review of precursors and near misses related
and, more recently, in railroad transport and
concepts
medicine [13].
Near misses management systems have been A. Precursors
developed and are implemented across a range of
Recognizing signals before an accident occurs
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offers the potential for improving safety, Many refer to as “small histories”—or fragments of what
organizations had sought to develop programs to might be experienced if an accident occurred [26].
identify and benefit from accident precursors, A To benefit from near misses, organizations ranging
recent study by the US National Academy of from hospitals to manufacturing facilities and
Sciences focused on these precursors which were airlines to power plants, have set up management
defined as the conditions, events and sequences systems for reporting and analyzing near misses
that preceded and led up to accidents or the [7], [15], [16], [27].
‘building blocks’ of accidents [2]. The National It has been widely accepted that accidents are
Academy of Engineering workshop definition of just the tip of an iceberg. Near accidents, events in
an accident precursor is any event or group of which no damages or injuries occur but, under
events that must occur for an accident to occur in a slightly different circumstances, could have
given scenario, Based on this definition a precursor resulted in harm, are important sources of
is identified in a much wider range of severities information about accident precursors [28], [29].
and may include all defects and abnormal events. Near misses accidents were usually referred to as
Similarly, Suraji et al. explained this concept as an precursors of accidents [7], indicators of potential
undesired event, which was an unwanted incident accidents when luck runs out [30] or imminent
immediately preceding and leading to an accident signals of accidents [16]. Ritwik adopted a very
that did, or could have caused injury to simple definition of near misses as an incident or
construction personnel or the general public, or unsafe condition with potential for injury or
damage to property or the environment [23]. property damage [31]. Phimister et al. defined near
Skogdalen and Vinnem described a precursor misses as an opportunity to improve environmental,
incident is an event or group of events that health and safety practice based on a condition, or
indicates failure in systems controlling the risks an incident with potential for more serious
from a major hazard [24]. When adopting a broad consequence [10]. Phimister et al. identified a near
definition of precursors, it is not difficult to find miss accident as a special kind of precursors and it
that a near miss accident is an important kind of was defined as an event in which no damages or
precursors [2], [19]. However, some organizations injuries actually occurred but, under slightly
such as the U.S. NRC, have chosen to limit the use different circumstances, could have resulted in
of the term ‘precursors’ to events that exceed a harm [2]. In construction, the modified statistical
specified level of severity. For example, precursors triangle of accident causation described the same
might be defined as the complete failure of one or process from near miss accidents to fatal accidents
more safety systems and/or the partial failure of [32]. Cambraia et al. adopted the concept of a near
two or more safety systems [2]. Likewise, Wu et al. miss accident as an instantaneous event that
adopted the concept of precursors to the events that involved the sudden release of energy and had the
exceed a specified level of severity [25]. potential to generate an accident [17]. Its
consequences do not result in personal injuries or
B. Near misses
material damage, but usually only in the loss of
To organizations seeking to learn about time. This concept also implies that a near miss has
potential accidents, near misses represent the potential to result in accidents with exclusively
inexpensive learning opportunities for analyzing material damages. Rathnayaka et al. describes the
what can go wrong. Near misses are especially term ‘near miss’ as an event that does not result in
important for organizations that have not an actual loss but that has the potential to do so
experienced a major accident, because they enable [33].
these organizations to experience what March et al.
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business operation, the concept do not refer to
C. Immediate factor
actual injury to a person [38]. Rathnayaka et al.
Undoubtedly, immediate factors are important
described an incident is an event that could cause
exacerbating factors of accidents. An updated
considerable harm or loss [33].
domino sequence led to the comprehension of
immediate causes before an accident [34]. Jones et E. Accident
al. defined the direct causes as immediate reason
Heinrich et al. considered an accident is
why an incident occurred, usually consisting of
unplanned and uncontrolled event in which the
unsafe conditions at the site or unsafe acts by a
action or reaction of an object, substance, person,
person [16]. Chua et al. described the immediate
or radiation results in personal injury or the
causes are the triggers that directly lead to the
probability thereof [38], Based on this definition
incident sequence, Further he classified the
accidents could encompass the idea of no injury
immediate causes into substandard/unsafe
accidents as well as injury accidents. Bentil
conditions and substandard/unsafe acts, which
described accident as an unplanned act, event or
refer to the respective physical conditions and
occurrence, within a sequence of events, which can
human behaviors that do not meet safety
cause unintended personal injury or death, property
requirements and can directly cause incident
damage or both [39]. Perrow defined an accident
occurrences [35]. Fang et al. found that immediate
as a failure in a subsystem, or the system as a
factors were caused by unsafe conditions and
whole, that damages more than one unit and in
unsafe actions [36]. The Loughborough’s ConCA
doing so disrupts the ongoing or future output of
accident causality model recognized that
the system [40]. Qureshi described an accident as
immediate accident circumstances were failures in
an event that occurs from inappropriate or
the interaction between the work team, workplace,
inadequate control or enforcement of safety-related
equipment and materials. Wu et al. adopted the
constraints on the development, design, and
same concept in their research [25].
operation of the system, rather than simply
occurring due to independent component failures
D. Incident
[41]. Rathnayaka et al. identified an accident as an
It is common to use the term near miss as a
event that may cause fatalities, damage to property
synonym of incident [19], [37]. However, some
and impact to the environment [33].
authors consider that incidents include accidents,
Simultaneously, accidents were classified
near misses, unsafe acts and conditions [13], [16],
according to the degree of severity by some
[18]. Similarly, Jones et al. defined incidents as all
research [16], [32], [33].
undesired events, including accidents and near
misses [16]. Phimister et al. defined incidents as all F. Harzard
safety related events, including accidents (with
We are surrounded by hazards all our lives.
negative outcomes, such as damage and injury),
Most of them we accept without concern [42].
near misses (situations in which accidents could
Bentil defined hazard is a condition, act or event
have happened if there had been no timely and
that has the potential of causing an accident or
effective recovery), and dangerous situations [2].
illness [39]. A hazard is “an inherent physical or
Cambraia et al. described incidents as an umbrella
chemical characteristic that has the potential for
term adopted to refer to any situation in which
causing harm to people, the environment, or
there is a lack of safety. There are different points
property” [43]. The Health and Safety Commission
of view in some research [17]. Heinrich et al.
defined hazard as the potential to cause harm [44].
defined an incident as an undesired event that
Hazard has also been defined as an inherent
could (or does) downgrade the efficiency of the
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characteristic of a thing or situation that has the accident is preceded by numerous incidents and
potential of causing an unplanned or undesired near misses in his famous iceberg metaphor [51].
event or series of events that have harmful Similarly, Investigation of major accidents shows
consequences, such as injury, death, environmental that for every serious accident, a larger number of
harm, or illness [45]. incidents result in limited impact and an even
larger number of incidents result in no loss or
F Safety barrier
damage [10]. Several authors mention the
The term safety barrier and similar terms like existence of precursors being present in the
defence (in-depth), layer of protection, safety organization before an accident occurs. For
(critical) function, safety critical element, and example, Lees and Tweeddale mention only
safety system are applied in regulations, standards, technical precursors [52], [53], whilst Reason,
and the scientific literature [46]. No common Turner, and Perrow indicate the presence of
definition of the term safety barrier has been found organizational precursors [19], [54], [55]. Various
in the literature, although different aspects of the accident triangles show that for each major
term have been discussed and applied in practice accident there are a large number of minor
for several decades. Safety barriers are categorized accidents and even more near misses [10], [32],
in numerous ways by different authors and the [53].
performance of the barriers is described in several It has been demonstrated in various studies, e.g.
(Bird and Germain, 1966; Tye, 1976；Heinrich,
ways.
In the Oxford English Dictionary a barrier is 1980) that there is a relationship between the
defined as a ‘‘fence of material obstruction of any numbers of near misses, minor incidents and major
kind erected (or serving) to bar the advance of accidents [38], [56], [57]. In order to effectively
persons or things, or to prevent access to a place’’ discuss, Phimister et al. defined precursors are
[47]. The concept of defence-in-depth constitutes sequences or events in the accident chain,
the basis for the discussion of safety barriers. accidents have been preceded by events, behaviors,
IAEA describes the term safety barrier is often and conditions that were ingredients of the recipe
used in a broader meaning as a collective term for for the adverse consequences [2]. On some
different means used to realize the concept of occasions a precursor event can be considered
defence in depth [48]. A safety barrier is related to synonymous with a near miss. Precursors are
a hazard, an energy source or an event sequence. signals of possible problems, chinks in an
This is supported by the requirement stated by operation’s armor, or pathways to accidents. They
PSA [49]. This means that a barrier should be well are called precursors rather than accidents because
defined or formalised and be related to a specific systems have multiple layers of defense like slices
hazard. Sklet suggests the definition of safety of Swiss cheese stacked together [19]. A precursor
barriers are physical and/or nonphysical means problem may pass through one or two layers of
planned to prevent, control, or mitigate undesired defense (through the holes in the Swiss cheese),
events or accidents [46]. but another layer usually stops the progression
toward an accident. Only when “all of the holes
III. Relationships between the aforementioned
line up” does the problem overcome or bypass all
concepts and differentiate the relevant concepts
defenses and become an accident.
In spite of all kinds of safety measures and It should be pointed out that when adopting a
indicators used, major catastrophes still occur [50]. broad definition of precursors, it is not difficult to
Were there no signs indicating that an accident was find that near miss is an important kind of
on its way? Heinrich already stated that an precursor [2], [16]. However, some organizations,
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such as the U.S. NRC, have chosen to limit the use between the terms near misses, unsafe acts and
of the term precursors to near misses that exceed a conditions. Cambraia et al. considered that the
specified level of severity [2]. Likewise Wu et al. difference between these events is in the time of the
adopted the same concept. Although near misses action and in whether or not there has been a sudden
are clearly related to precursors [25], Phimister et release of energy [17]. While in unsafe acts and
al. have tried to distinguish near misses from conditions, the situation of risk arises from a
precursors, and encourage not to use them continuous action or is latent in the environment
interchangeably [2]. They define a near miss is as (for example, an employee working high up who
an almost complete progression of events—a does not use a safety belt), in near misses there is an
progression that, if one other event had occurred, instantaneous action, which involves the sudden
would have resulted in an accident. A near miss release of energy.
might consist of one or more precursors that did Immediate factors are important exacerbating
occur, and one that did not. Based on this factors of accidents on construction sites. An
definition, a near miss can be considered a updated domino sequence led to the
particularly severe precursor. For instance, when comprehension of immediate cause before an
the necessary exacerbating factors are highly likely, accident [34]. Differences between precursors and
the precursor is called a near miss. Similarly, one immediate factors lie in the difficulty for
would expect a precursor to be called a near miss if performing preventive actions due to time
the mitigating factors were unlikely or not robust. constraint. Immediate factors always have tight
Likewise Meel and Seider described the near period allowed for taking actions [25].
misses and incidents are also called accident In this study, the general definition of precursors,
precursors as their occurrences portend an near misses, immediate factors, incident, accident,
increasing likelihood of accidents, near misses have hazard and safety barriers have been used [2], [16],
less potential for adverse scenarios compared with [45], [46]:
incidents, but when recognized, they signal the The precursors are defined as sequences or
likelihood of future incidents and accidents, often in events in the accident chain, a precursor problem
time to take preventive action [58]. By reviewing may pass through one or two layers of defense
previous research, the relationship between the (through the holes in the Swiss cheese), but
numbers of precursors, near misses, minor another layer usually stops the progression toward
incidents and major accidents could be described an accident. A near miss is defined as an almost
by the well known Safety Pyramid [56] shown in complete progression of events—a progression that,
Fig. 1. if one other event had occurred, would have
resulted in an accident. Immediate factors are
defined as immediate causes before an accident.
Incidents are defined as all safety related events,
including accidents, near misses and precursors. A
accident is defined as an complete progression of
events (all of the holes in the Swiss cheese line up).
A hazard is defined as an inherent characteristic of
a thing or situation that has the potential of causing
an unplanned or undesired event or series of events
that have harmful consequences, such as injury,
Fig. 1. Safety pyramid (the lowest strata, precursors, is not
death, environmental harm, or illness (holes in the
shown by Bird and Germain, 1966)
It is also common for no distinction to be made Swiss cheese). Safety barriers are defined as
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physical and/or non-physical means planned to
prevent, control, or mitigate undesired events or
accidents.
According to the above definitions, the
presented paper described the relationships of the
above concepts by a causal sequence diagram (Fig.
2).
Based on the Safety pyramid (Fig.1) and the
causal sequence diagram (Fig.2), this paper
differentiate the precursors, near misses and
accidents from three aspects of proximity, incidents
rates, potential consequence by a bubble chart
(Fig.3). Fig.3. Bubble chart
Fig. 2. Causal sequence diagram of the accident
‘‘building blocks’’ of accidents [2].
IV. The importance of precursors and near
Grabowski et al. also echoed that recognizing
misses to further improve safety margins
alerts and signals before an accident clearly
A primary purpose in measuring safety is to
offers the potential of improving safety [59].
develop intervention strategies to avoid future
In the aftermath of catastrophes, it is
accidents [59]. Recognizing signals before an
common to find prior indicators, missed
accident occurs offers the potential for
signals, and dismissed alerts that, had they
improving safety, and many organizations
been recognized and appropriately managed
have sought to develop programs to identify
before the event, might have averted the
and benefit from alerts, signals and prior
undesired event [2]. To prevent major, though
indicators. A recent study by the US National
infrequent, event occurrence, it is important to
Academy of Sciences focused on these signals,
consider accident precursors (symptoms of
the conditions, events and sequences that
hazards) such as operational deviations,
precede and lead up to accidents, or the
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mishaps, and near misses, in order to prevent Commission (NRC) for almost twenty years
events at source rather than controlling or [24]. For a given accident scenario, near
mitigating them [33]. One of the most misses can and frequently do occur with
attractive aspects of precursors analysis is the greater frequency than the actual event [56].
abundance of precursors events compared to Similarly, the “Iceberg concept” about the
actual accidents [56]. Analyzing precursors proportionality between different categories of
data can therefore reduce the uncertainty accidents and near misses also says that the
about the likelihood of an accident and lead to more near misses (or other deviations) you
better decisions. The relatively high frequency have the more frequently you will have
and low cost associated with precursor events accidents.
suggest that many industries could benefit To organizations seeking to learn about
from using precursors analyses to reduce the potential accidents, near misses represent
risk of accidents. inexpensive learning opportunities for
Programs for managing accident precursors analyzing what can go wrong. Near misses are
have a number of benefits, as outlined by van especially important for organizations that
der Schaaf et al. [14]. First, reviewing and have not experienced a major accident,
analyzing observed precursors can reveal what because they enable these organizations to
can go wrong with a particular system or experience what March et al. refer to as “small
technology and how accidents can develop histories”—or fragments of what might be
experienced if an accident occurred [26]. To
(modeling). Second, because precursors
generally occur much more often than benefit from near misses, organizations
accidents, analyses of accident precursors can ranging from hospitals to manufacturing
help in trending the safety of a system facilities and airlines to power plants, have set
(monitoring). Finally, and perhaps most up management systems for reporting and
important, precursors programs can improve analyzing near misses [7], [15], [16], [27].
organizational awareness (mindfulness) of As near misses are much more frequent
safety problems [60]. The investigation of events that accidents, they may indicate, in a
precursor events can be used as a source of proactive way, critical areas for improvement
information for the construction of a in safety management [16], [19], [22], [37]. In
structured methodological approach for addition, using near misses helps to strengthen
operational decisions [61]. Skogdalen and the safety culture [16], [62], [63], especially
Vinnem thought that information from when workers are motivated to participate in
precursor incidents investigations can also be the process of identification and analysis of
important tools for improved risk those events [16], [19]. Indeed, studies in the
communication [24]. construction and chemical industries have
One way organizations seek to benefit from indicated that accident rates tend to diminish
precursors is by analyzing near misses in keeping with the rate at which the number
(sometimes referred to as near accidents, near of near misses identified increases [16], [64].
hits, or close calls), fragments of an accident So if we report near misses, and learn from
scenario that can be observed in them, we will eventually get to the point
isolation—without the occurrence of an where near misses occurrence itself reduces. A
accident [10]. Precursors analysis, the reduction in the numbers of near misses which
evaluation of “near misses,” has been an proceed to full-blown accidents follows.
activity of the U.S. Nuclear Regulatory
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V. Risk-based evaluation Table I
Data for relevance index
In this passage, a decision matrix risk
Relevance index
assessment technique is presented, which has
Criteria Weighting
been based on and produced with the help of
1.Proximity index
the works of Johnson, Woodruff, Reniers et al.,
How far away was the incident from becoming a accident?
Marhavilas and Koulouriotis [65][68].
One step away 3
The combination of a relevance index and
Two steps away 2
consequence potential factor range, gives us
More than two steps away 1
an estimate of risk (or a risk ranking). The
Remote 0
relevance index is composed of proximity
2.Visibility index
index (1), visibility index (2) and Probability
Is the incident visible before it lead to the accident?
index (3). The consequence potential factor is
With great difficulty 3
composed of casualties (a), property Loss (b),
Some insight 2
environmental releases/exceeding standards (c)
Obvious 1
and evacuation (d).
Widely know 0
Furthermore, the product of the relevance
3. Probability index
index and consequence potential factor
Occurrence rate of the incident in daily operation.
provides a measure of risk which is expressed
High probability 3
by the relation:
Medium probability 2
Relevance index=1+2+3
Low probability 1
Consequence potential factor=a×b×c×d
Not expected to happen 0
In order to reduce the subjectivity of the
Relevance index (1+2+3) 0 to 9
evaluation, criteria were established to classify
precursors or near misses according to their
Table II
degree of severity (level of impact if the
Data for consequence potential factor
accident had happened), proximity (how far
Consequence potential factor Weighting
away was the incident from becoming a
a) Casualties
accident),visibility (is the incident visible
Death 3
before it lead to the accident) and probability
Serious injury 2
(estimate of the likelihood of an accident
Injury 1
occurring if no preventive action additional to
b) Property Loss
those already in place is taken), as shown in
$500,000 or more 3
Tables Ⅰ and Ⅱ Criteria and their weightings
.
$50,000-500,000 2
could be customized to suit local needs.
$0-50,000 1
Once the precursors or near misses has
c) Environmental releases/ Exceeding standards
been identified, the question of assigning
8 hours or 100% 3
relevance index and consequence potential
1 hour or 10% 2
factor must be addressed, like in Tables 1 and
30 minutes or 5% 1
2. It is very important to note that frequency
d) Evacuation
estimations and consequence estimations are
More than 100 individuals 3
very well considered and performed by
50-100 individuals 2
experienced risk managers [67].
Less than 50 individuals 1
Eventually, the technique is consummated
Consequence potential factor (a×b×c×d) 0 to 81
by the construction of the risk matrix (in Fig.
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4), which have been developed by the or near miss will be the basis to classify the
combination of Tables and and the usage incident in one out of three zones of risk (Fig.
of the above relation. 4): red (incidents with the highest risk),
The developed decision matrix risk yellow (incidents with medium risk) and green
assessment technique has two key advantages: (incidents with the lowest risk). The red zone
a) It differentiates relative risks to facilitate means that not enough barriers have been
decision making. b) It improves the implemented and risk cannot be tolerated. The
consistency and basis of decision. Moreover, it yellow and green zones finally state that
is a quantitative (due to risk measuring) and enough layers of protection are present in
also a graphical method which can create order not to select the scenario. The
liability issues and help the risk managers to classification in zones is necessary since the
prioritize and manage key risks. choice was made not to assign weights to rank
The relevance index and consequence each category of relevance index and severity.
potential factor associated with each precursor
Fig. 4. Risk matrix of precursors and near misses
precursors [9].
VI. Impacts on quantitative risk estimates
Since precursors (near misses) consist of
In estimating the frequency of rare events, event sequences rather than individual
the number of observed events (typically component failures, precursors data will
either 0 or 1) will generally be too small to automatically reflect the effects of any
support the development of accurate estimates dependencies that may exist between
by means of the usual statistical estimator, components or systems that were challenged
Two alternative approaches have been during the observed precursors [6]. The
suggested to overcome this problem: (1) analysis of precursors data has therefore
probabilistic risk analysis (PRA), in which the attracted considerable attention as an approach
accident frequency is estimated as a function for estimating the frequencies of severe
of the failure rates of individual components; accidents.
As it is well known, the occurrence rate Φ
and (2) the use of data on accident “precursors”
or “near misses” [6]. Kirchsteiger thought that of an accident of a certain type with
the significance of quantitative risk estimates consequences equalling or exceeding a certain
depends not only on the number of accident magnitude can be quantified as a
events included, but also on the criteria maximum-likelihood estimate across the given
differentiating accidents and accident observation time T,
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specific accident type under consideration) is
.
Ф|T= 。
often quite large compared to the number of
accidents — “conventional” risk estimates of
Taking into account precursors or near
misses, the frequency of an accident can be the
represented as the product of two quantities, .
Ф|T= 。
Ф|T=∑ λkφk
where, Ф| T = frequency of a specific type are not very dependable.
accident in observation time T (e.g. fire in a
VII. Conclusions
plant with fatalities or injuries > 0), λk =
frequency of precursors or near misses type k The concepts of precursors, near misses are
(e.g. any fire in the plant), φk = conditional presented and discussed in the paper. The
frequency of the accident of interest, given a results are based on experience from several
precursors or near misses of type k (e.g. fire research projects focusing on precursors, near
with fatalities or injuries > 0, given any fire) misses and a review of relevant literature. No
[16]. common terminology applicable crosswise
Based on the above discussion, Jones et al. between sectors and application areas has been
described near misses can thus be viewed to found, and a set of definitions is therefore
yield either an increased or a decreased overall proposed in the paper.
accident frequency by either increasing the Precursors are defined as sequences or
near misses frequency or decreasing the events in the accident chain, a precursor
conditional frequency of an accident given a problem may pass through one or two layers
near misses, depending on the prior of defense (through the holes in the Swiss
distributions for both the near misses cheese), but another layer usually stops the
frequency and the conditional accident progression toward an accident. While near
frequency [16]. miss is defined as an almost complete
The question of interest is thus whether the progression of events—a progression that, if
inclusion of observations of precursor and near one other event had occurred, would have
miss events which do not end up in accidents resulted in an accident. Accident is defined as
can actually result in significantly different a complete progression of events (all of the
(increased or decreased) accident frequencies holes in the Swiss cheese line up). So defined
and thus overall risk estimates. As analytically in order to facilitate the distinction between
shown in Kirchsteiger [9], the inclusion of near precursors, near misses and accidents.
misses events not resulting in an accident has It has been demonstrated in various studies,
e.g. (Bird and Germain, 1966; Tye, 1976 ；
the potential to significantly increase the
values of corresponding risk estimates. In other Heinrich, 1980) [38], [56], [57] that there is a
words, not considering precursors and near relationship between the numbers of precursors,
misses occurrences can result in significant near misses, minor incidents and major
under estimation of the “true” risk. accidents. Investigation of major accidents
Thus, if the statistical basis for quantitative shows that for every serious accident, a larger
risk estimates consists only of “top events” (e.g. number of near misses and an even larger
accidents of a certain type) instead of explicitly number of precursors. In this paper, the author
covering both accidents and accident described the relationship between precursors,
precursors, there is the danger that—since the near misses and accidents by a Safety pyramid,
number of near misses (i.e. of precursors to the Causal sequence diagram of the accident and a
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- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 49
Bubble chart. ACKNOWLEDGMENT
The importance of precursors and near
The authors would like to express sincere
misses to further improve safety margins has
thanks to Institute of Construction and Real
been emphasized. Analyzing precursors data
Estate, Southeast University for endless
can therefore reduce the uncertainty about the
support throughout this project.
likelihood of an accident and lead to better
decisions. The relatively high frequency and References
low cost associated with precursors events
[1] M. Kalantarnia, F. Khan and K. Hawboldt.
suggest that many industries could benefit
Dynamic risk assessment using failure
from using precursors analyses to reduce the
assessment and Bayesian theory, Journal
risk of accidents.
of Loss Prevention in the Process
To organizations seeking to learn about
Industries, vol. 22, 2009, pp. 600–606.
potential accidents, near misses represent
[2] J. R. Phimister, V. M. Bier and H. C.
inexpensive learning opportunities for
Kunreuther(Eds). Accident Precursors
analyzing what can go wrong. Near misses are
Analysis and Management: Reducing
especially important for organizations that
Technological Risk through Diligence,
have not experienced a major accident,
National Academy Press, Washington, DC,
because they enable these organizations to
2004.
experience what March et al. [26] refer to as
[3] M. B. Sattison. Nuclear accident
“small histories”—or fragments of what might
precursors assessment: The accident
be experienced if an accident occurred.
sequence precursors program, In J. R.
In this paper, a decision matrix risk
Phimister, V. M. Bier and H. C.
assessment technique is presented. The
Kunreuter(Eds). Accident Precursors
combination of a relevance index and
Analysis and Management: Reducing
consequence potential factor range, gives us
Technological Risk through Diligence (pp.
an estimate of risk (or a risk ranking). The
89–100). National Academic Press,
developed decision matrix risk assessment
Washington, DC, 2004.
technique is a quantitative (due to risk
[4] J. E. Vinnem, J. A. Hestad and J. T.
measuring) and also a graphical method which
Kvaløy. Analysis of root causes of major
can create liability issues and help the risk
hazard precursors (hydrocarbon leaks) in
managers to prioritize and manage key risks.
the Norwegian offshore petroleum
The impact of precursors and near misses on
industry, Reliability Engineering and
quantitative risk estimates has also been
System Safety, vol. 95, 2010, pp.
emphasized. If the statistical basis for
1142–1153.
quantitative risk estimates consists only of “top
[5] C. L. Smith and E. Borgonovo. Decision
events” (e.g. accidents of a certain type)
Making During Nuclear Power Plant
instead of explicitly covering both accidents
Incidents—A New Approach to the
and accident precursors, there is the danger
Evaluation of Precursors Events, Risk
that—since the number of near misses (i.e. of
Analysis, vol. 27, 2007, pp. 1027–1042.
precursors to the specific accident type under
[6] V. M. Bier and W. Yi. The performance of
consideration) is often quite large compared to
precursors-based estimators for rare event
the number of accidents—“conventional” risk
frequencies, Reliability Engineering and
estimates are not very dependable.
System Safety, vol. 50, 1995, pp.
241–251.
124303-7474 IJET-IJENS @ June 2012 IJENS
IJENS
- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 50
[7] V. M. Bier, and A. Mosleh. The analysis tool, Oxford: Butterworth-Heinmann,
of accident precursors and near misses: 1991.
Implications for risk assessment and risk [15] T. W. Van Der Schaaf. Near misses
management, Reliability Engineering and Reporting in the Chemical Process
System Safety, vol. 27, 1990, pp. 91–101. Industry, Eindhoven University of
[8] S. Kaplan. On the inclusion of precursors Technology, the Netherlands, 1992.
and near misses events in quantitative risk [16] S. Jones, C. Kirchsteiger and W. Bjerke.
assessments: A Bayesian point of view The importance of near misses reporting to
and a space shuttle example, Reliability further improve safety performance,
Engineering and System Safety, vol. 27, Journal of Loss Prevention in the Process
1990, pp. 103–115. Industries, vol. 12, 1999, pp. 59–67.
[9] C. Kirchsteiger. Impact of accident [17] F. B. Cambraia, T. A. Saurin and C. T.
precursors on risk estimates from accident Formoso. Identification, analysis and
databases, Journal of Loss Prevention in dissemination of information on near
the Process Industries, vol. 10, 1996, pp. misses: A case study in the construction
159–167. industry, Safety Science, vol. 48, 2010, pp.
[10] J. R. Phimister, U. Oktem, Kleindorfer P 91–99.
R, et al. Near-Miss Incident Management [18] A. J. Brazier. A summary of incident
in the Chemical Process Industry, Risk reporting in the process industry, Journal
Analysis, vol. 23, 2003, pp. 445–459. of Loss Prevention in the Process
[11] E. Paté-Cornell. On signal, response and Industries, vol. 7, 1994, pp. 243–248.
risk mitigation: A probabilistic approach [19] J. Reason. Managing the Risks of
to the detection and analysis of precursors, Organizational Accidents, Ashgate,
In J. R. Phimister, V. M. Bier and H. C. Burlington, 1997.
Kunreuter(Eds). Accident Precursors [20] P. F. Renshaw and M. W. Wiggins. A
Analysis and Management: Reducing self-report critical incident assessment tool
Technological Risk through Diligence (pp. for army night vision goggle helicopter
49–59). National Academic Press, operations, Human Factors, vol. 49, 2007,
Washington, DC, 2004. pp. 200–213.
[12] J. S. Carroll. Knowledge management in [21] S. Dekker. Just Culture: Balancing Safety
high hazard industries, In J. R. Phimister, and Accountability. Ashgate, London,
V. M. Bier and H. C. Kunreuter(Eds). 2007.
Accident Precursors Analysis and [22] T. W. Van Der Schaaf. Near misses
Management: Reducing Technological reporting in the chemical process industry:
Risk through Diligence (pp. 127–136), an overview, Microelectronics and
National Academic Press, Washington, Reliability, vol. 35, 1995, pp. 1233–1243.
DC, 2004. [23] A. Suraji, A. R. Duff and S. J. Peckitt.
[13] T. W. Van Der Schaaf and L. Kanse. Development of causal model of
Biases in incident reporting databases: an construction accident causation, Journal of
empirical study in the chemical process Construction Engineering and
industry, Safety Science, vol. 42, 2004, pp. Management, vol. 127, 2001, pp. 337–344.
57–67. [24] J. E. Skogdalen and J. E. Vinnem.
[14] T. W. Van der Schaaf, D. A. Lucas and A. Quantitative risk analysis
R. Hale. Near-miss reporting as a safety offshore—Human and organizational
124303-7474 IJET-IJENS @ June 2012 IJENS
IJENS
- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 51
factors, Reliability Engineering and [34] F. Bird. Management Guide to Loss
System Safety, vol. 96, 2011, pp. Control, Institute Press, Atlanta, 1974.
468–479. [35] D. K. H. Chua. M. ASCE and Y. M. Goh.
[25] W. Wu, H. Yang, D. A. S. Chew, S. Yang Incident Causation Model for Improving
and Q. M. Li. Towards an autonomous Feedback of Safety Knowledge. Journal of
real-time tracking system of near misses Construction Engineering and
accidents on construction sites, Management, vol. 130, 2004, pp. 542–551.
Automation in Construction, vol. 19, 2010, [35] D. P. Fang. Y. Chen and L. Wong. Safety
pp. 134–141. climate in construction industry: a case
[26] J. G. March, L. S. Sproull and M. Tamuz. study in Hong Kong, Journal of
Learning from samples of one or fewer, Construction Engineering and
Organization Science, vol. 2. 1991, pp. Management, vol. 132, 2006, pp. 573–584.
1–13. [36] A. Gibb. R. Haslam, D. Gyi, et al. What
[27] P. Barach, and S. D. Small. Reporting causes accidents? Proceedings of the
and preventing medical mishaps: lessons institution of civil engineers, Civil
from non-medical near misses reporting engineering, vol. 159. 2006, pp. 46–50.
systems, British Medical Journal, vol. 320, [37] J. Hinze. Construction Safety.
2000, pp. 759–763. Prentice-Hall, Upper Saddle River, NJ,
[28] NRC (National Research Council). 1997.
Improving Aircraft Safety: FAA [38] H. W. Heinrich, D. Petersen and N. Roos.
Certification of Commercial Passenger Industrial Accident Prevention: A Safety
Aircraft, Washington, D.C.: National Management Approach, McGraw-Hill, Inc,
Academy of Sciences, 1980. New York, 1980.
[29] M. Tamuz. The impact of computer [39] K. K. Bentil. A Model for Predicting
surveillance on air safety reporting, Commercial Construction Site Accidents,
Columbia Journal of World Business, vol. University of Florida, 1990.
22, 1987, pp. 69–77. [40] C. Perrow. Normal Accidents. Princeton,
[30] A. J. Brazier. A summary of incident N.J.: Princeton University Press, 1999.
reporting in the process industry, Journal [41] Z. H. Qureshi. A review of accident
of Loss Prevention in the Process modeling approaches for complex
Industries, vol. 1994, pp. 243–248. socio-technical systems, In: Proc. 12th
[31] U. Ritwik. Risk-based approach to near Australian Conference on Safety-Related
misses, Safety management, 2002. Programmable Systems, Adelaide,
[32] G. Carter, and S. D. Smith. Safety hazard Australia, 2007.
identification on construction projects, [42] M. Tweeddale. Managing Risk And
Journal of Construction Engineering and Reliability Of Process Plants , Copyright
Management, vol. 132, 2006, pp. 197–205. © 2003 by Elsevier Science (USA).
[33] S. Rathnayaka, F. Khan and P. Amyotte. [43] CCPS (Center for Chemical Process
SHIPP methodology: Predictive accident Safety). Guidelines for Hazard Evaluation
Procedures, 2nd ed, New York: American
modeling approach. Part I: Methodology
and model description, Process Safety and Institute of Chemical Engineers, 1992.
Environmental Protection, vol. 89, 2011, [44] Health and Safety Commission.
pp. 151–164. Designing for health and safety in
construction, HSE Books, London, 1995.
124303-7474 IJET-IJENS @ June 2012 IJENS
IJENS
- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 52
[45] L. D. Gowen, J. S Collofollo. Software [57] J. Tye. Accident Ratio Study. London:
safety and preliminary hazard analysis. British Safety Council, 1976.
Prof. Saf, 1994, pp. 20–25. [58] A. Meel and W. D. Seider. Plant-specific
[46] S. Sklet. Safety barriers: Definition, dynamic failure assessment using
classification, and performance. Journal of Bayesian theory. Chemical Engineering
Loss Prevention in the Process Industries, Science, vol. 61, 2006, pp. 7036–7056.
vol. 19, 2006. pp. 494–506. [59] M. Grabowski, P. Ayyalasomayajula, J.
[47] OED. Oxford English dictionary online. Merrick, et al. Leading indicators of safety
Oxford: Oxford University Press, 2005. in virtual organizations, Safety Science,
[48] IAEA. Basic safety principles for nuclear vol. 45, 2007, pp. 1013–1043.
power plants: 75-INSAG-3, rev.1. Vienna: [60] K. E. Weick and K. M. Sutcliffe.
The International Atomic Energy Agency, Managing the Unexpected: Assuring High
1999. Performance in an Age of Complexity,
[49] PSA. Regulations relating to management New York: John Wiley and Sons, 2001.
in the petroleum activities (The [61] E. Borgonovo, C. Smith, G. Apostolakis,
Management Regulations), Norway, et al. Insights from using influence
Stavanger: Petroleum Safety Authority, diagrams to analyze precursor events,
2001. FRONTIERS SCIENCE SERIES. vol. 3,
[50] P. J. M. Sonnemans and P. M. W. 2000, pp. 1801-1808.
Korvers. Accidents in the chemical [62] M. D. Cooper. Towards a model of safety
industry: are they foreseeable?, Journal of culture, Safety Science, vol. 36, 2000, pp.
Loss Prevention in the Process Industries, 111–136.
vol. 19, 2006, pp. 1–12. [63] A. I. Glendon, and N. A. Stanton.
[51] H. W. Heinrich. Industrial accident Perspectives on safety culture, Safety
prevention. McGraw-Hill New York, Science, vol. 34, 2000, pp. 193–214.
1931. [64] J. Hinze. Making Zero Injuries a Reality,
[52] F. P. Lees. Hazard warning structure: A Report to the Construction Industry
Some illustrative examples based on actual Institute, University of Florida,
cases, Reliability engineering, vol. 10, Gainesville, Report 160, 2002.
1982, pp. 65–81. [65] W. G. Johnson. The management
[53] H. M. Tweeddale. Principles and oversight and risk tree. Prepared for the
practices for design of process safety U.S. Atomic Energy Commission, 1973.
monitoring and auditing programmes, [66] J. M. Woodruff. Consequence and
Loss prevention and safety promotion in likelihood in risk estimation: a matter of
the process industries, vol. 1, 1995, pp. balance in UK health and safety risk
71–82. assessment practice, Safety Science, vol.
[54] B. A. Turner. Man-made disasters. 43, 2005, pp. 345–353.
London:Wykeham Publications Ltd, 1978. [67] G. L. L. Reniers, W. Dullaert, B. J. M.
[55] C. Perrow. Normal accidents. New York: Ale, et al. Developing an external domino
Basic Books, 1984. prevention framework: Hazwim, Journal
[56] F. E. Bird and G. L. Germain. Practical of Loss Prevention in the Process
loss control leadership. Loganville, GA: Industries, vol. 18, 2005, pp. 127–138.
Det Norske Verita, 1966. [68] P. K. Marhavilas, D. E. Koulouriotis and
C. Mitrakas. A new approach to risk
124303-7474 IJET-IJENS @ June 2012 IJENS
IJENS
- International Journal of Engineering & Technology IJET-IJENS Vol: 12 No: 03 53
assessment using a combined conference of the Hellenic Operational
qualitative-quantitative evaluation Research Society (HELORS), 2008, pp.
technique with real accidents data: 1261–1274.
application on an electric power provider
industry, In Proceedings, 20th national
124303-7474 IJET-IJENS @ June 2012 IJENS
IJENS
nguon tai.lieu . vn
