ARAMIS project: a more explicit demonstration of risk control through the use of bow-tie diagrams and the evaluation of safety barrier performance

Over the last two decades a growing interest for risk analysis has been noted in the industries. The ARAMIS project has defined a methodology for risk assessment. This methodology has been built to help the industrialist to demonstrate that they have a sufficient risk control on their site.

Risk analysis consists first in the identification of all the major accidents, assuming that safety functions in place are inefficient. This step of identification of the major accidents uses bow–tie diagrams. Secondly, the safety barriers really implemented on the site are taken into account. The barriers are identified on the bow–ties. An evaluation of their performance (response time, efficiency, and level of confidence) is performed to validate that they are relevant for the expected safety function. At last, the evaluation of their probability of failure enables to assess the frequency of occurrence of the accident. The demonstration of the risk control based on a couple gravity/frequency of occurrence is also possible for all the accident scenarios.

During the risk analysis, a practical tool called risk graph is used to assess if the number and the reliability of the safety functions for a given cause are sufficient to reach a good risk control.     

Multiple-vehicle traffic accidents in Hong Kong

‘Multiple-vehicle traffic accident’ refers to a crash between two or more moving objects. Unlike single-vehicle accidents, not all drivers involving in a multiple-vehicle accident are responsible for the occurrence of the event. Accordingly, variables such as road type, speed limit and number of vehicles involved in the accident are expected to play a much more important role in association with injury severity in multiple-vehicle accidents. To study the factors influencing injury severity of multiple-vehicle traffic accidents, a population-based study was conducted. The traffic accident data was obtained from the Traffic Accident Data System (TRADS), which was developed by the Transport Department, Police Force and Information Technology Services Department, Hong Kong. Multiple-vehicle traffic accidents (N = 10,630) occurring during the 2-year period 1999/2000 were considered. Potential risk factors such as district, human, vehicle, safety, environmental and site factors were examined. Categorizing injury severity into “fatal/serious” and “slight”, a stepwise logistic regression model was applied to the population data set. The district board, time of the accident, driver's gender, vehicle type, road type, speed limit and the number of vehicles involved are significant factors influencing the injury severity. Identification of risk factors for severe traffic accidents provides valuable information to help with new and improved road safety control measures.     

A study of driver experience and vehicle familiarity in accidents

A separate study was performed as part of a major accident investigation project to (1) test the hypothesis that drivers of vehicles involved in investigated accidents had less driving experience than the general driving population, and (2) test the hypothesis that accident involved drivers were less familiar with their vehicles than the general driving population. A Kolmogorov-Smirnov one-tail test was employed to evaluate the differences in the distributions of driver experience and vehicle familiarity between the “accident sample” and a “control sample.” Results indicated that drivers involved in the investigated accidents had less driving experience in general and had less driving experience with the accident vehicles than drivers in the general population. These effects are discussed briefly and further studies are suggested.     

Storybuilder—A tool for the analysis of accident reports

As part of an ongoing effort by the ministry of Social Affairs and Employment of The Netherlands a research project is being undertaken to construct a causal model for the most commonly occurring scenarios related to occupational risk. This model should provide quantitative insight in the causes and consequences of occupational accidents. The results should be used to help selecting optimal strategies to reduce these risks taking the costs of accidents and of measures into account. The research is undertaken by an international consortium under the name of Workgroup Occupational Risk Model. One of the components of the model is a tool to systematically classify and analyse past accidents. This tool: “Storybuilder” and its place in the Occupational Risk Model (ORM) are described in the paper.The paper gives some illustrations of the application of the Storybuilder, drawn from the study of ladder accidents, which forms one of the biggest single accident categories in the Dutch data.     

Inherent safety, ethics and human error

A patient is to have the damaged left kidney removed. To safeguard correctness of action several layers of expert checks have been performed prior to the operation, which results in the removal of the fully functional right kidney. Nobody asked the patient. The patient did not volunteer providing “unnecessary” information. The experts know everything …

An untidy house made out of flammable materials. A careless smoker left his lit cigarette unattended. A blow of wind and the house comes in flames. Would better construction materials have prevented the accident in spite of the carelessness of the inhabitant

A tricky medical condition which is expected to provoke a patient's fast health deterioration and their slow death. The doctor takes the initiative and responsibility of performing a risky operation. The patient's life is saved and their health is re-established.

This work is not, as initially intended, the result of a thorough investigation of accidents, neither contains a systematic collection of data that can support the conclusions or the suggestions made. It is in the main a compilation of personal views. These views have been established from the correlation of the results of numerous accident investigation reports with the causes of small and insignificant incidents. These incidents are related with the education of university students, regulations within an academic environment and from independent personal experience working in different countries and with people of different cultures. The analysis that follows, however, should not be perceived as a mere reference to university students and/or to a university environment. University is the place where the fundamental scientific and engineering principles are germinated while current and past university students are the future and current production and design engineers, respectively. The places where the presented incidents have occurred are not always relevant with the conclusions, thus they are not stated. The reason this article is presented here is that I believe that often, complex accidents, similarly to insignificant ones, often demonstrate an attitude which can be characterized as “inherently unsafe”. I take the view that the enormous human potential and the human ability to minimize accidents needs to become a focal point towards inherent safety. Restricting ourselves to human limitations and how we could “treat” or prevent humans from not making accidents needs to be re-addressed.

The purpose of this presentation is to highlight observations and provoke a discussion on how we could possibly improve the understanding of safety related issues. I do not intent to reject or criticize existing methodologies. (The entire presentation is strongly influenced by Trevor Kletz's work although our views are often different.)     

Scenario analysis of freight vehicle accident risks in Taiwan

This study develops a quantitative risk model by utilizing Generalized Linear Interactive Model (GLIM) to analyze the major freight vehicle accidents in Taiwan. Eight scenarios are established by interacting three categorical variables of driver ages, vehicle types and road types, each of which contains two levels. The database that consists of 2043 major accidents occurring between 1994 and 1998 in Taiwan is utilized to fit and calibrate the model parameters. The empirical results indicate that accident rates of freight vehicles in Taiwan were high in the scenarios involving trucks and non-freeway systems, while; accident consequences were severe in the scenarios involving mature drivers or non-freeway systems. Empirical evidences also show that there is no significant relationship between accident rates and accident consequences. This is to stress that safety studies that describe risk merely as accident rates rather than the combination of accident rates and consequences by definition might lead to biased risk perceptions. Finally, the study recommends using number of vehicle as an alternative of traffic exposure in commercial vehicle risk analysis. The merits of this would be that it is simple and thus reliable; meanwhile, the resulted risk that is termed as fatalities per vehicle could provide clear and direct policy implications for insurance practices and safety regulations.     

A logical model for quantification of occupational risk

Functional block diagrams (FBDs) and their equivalent event trees are introduced as logical models in the quantification of occupational risks. Although a FBD is similar to an influence diagram or a belief network it provides a framework for introduction in a compact form of the logic of the model through the partition of the paths of the equivalent event tree. This is achieved by consideration of an overall event which has as outcomes the outmost consequences defining the risk under analysis. This event is decomposed into simpler events the outcome space of which is partitioned into subsets corresponding to the outcomes of the initial joint event. The simpler events can be further decomposed into simpler events creating a hierarchy where the events in a given level (parents) are decomposed to a number of simpler events (children) in the next level of the hierarchy. The partitioning of the outcome space is transferred from level to level through logical relationships corresponding to the logic of the model.Occupational risk is modeled trough a general FBD where the undesirable health consequence is decomposed to “dose” and “dose/response”; “dose” is decomposed to “center event” and “mitigation”; “center event” is decomposed to “initiating event” and “prevention”. This generic FBD can be transformed to activity—specific FBDs which together with their equivalent event trees are used to delineate the various accident sequences that might lead to injury or death consequences.The methodology and the associated algorithms have been computerized in a program with a graphical user interface (GUI) which allows the user to input the functional relationships between parent and children events, corresponding probabilities for events of the lowest level and obtain at the end the quantified corresponding simplified event tree.The methodology is demonstrated with an application to the risk of falling from a mobile ladder. This type of accidents has been analyzed as part of the Workgroup Occupational Risk Model (WORM) project in the Netherlands aiming at the development and quantification of models for a full range of potential risks from accidents in the workspace.     

A global view on ARAMIS, a risk assessment methodology for industries in the framework of the SEVESO II directive

The ARAMIS methodology was developed in an European project co-funded in the fifth Framework Programme of the European Commission with the objective to answer the specific requirements of the SEVESO II directive. It offers an alternative to purely deterministic and probabilistic approaches to risk assessment of process plants. It also answers the needs of the various stakeholders interested by the results of the risk assessment for land use or emergency planning, enforcement or, more generally, public decision-making. The methodology is divided into the following major steps: identification of major accident hazards (MIMAH), identification of the safety barriers and assessment of their performances, evaluation of safety management efficiency to barrier reliability, identification of reference accident scenarios (MIRAS), assessment and mapping of the risk severity of reference scenarios and of the vulnerability of the plant surroundings. The methodology was tested during five case studies, which provided useful information about the applicability of the method and, by identifying the most sensitive parts of it opened way to new research activity for an improved industrial safety.     

Identification of reference accident scenarios in SEVESO establishments

In the frame of the ESREL special session on ARAMIS project, this paper aims at presenting the work carried out in the first Work Package, devoted to the definition of accident scenarios. This topic is a key-point in risk assessment, and serves as basis for the whole risk quantification. A first part of the work aims at building a Methodology for the Identification of Major Accident Hazards (MIMAH), which is carried out with the development of generic fault and event trees based on a typology of equipment and substances. This work is coupled with an historical analysis of accidents. In a second part, influence of safety devices and policies will be considered, in order to build a Methodology for the Identification of Reference Accident Scenarios (MIRAS). This last one will take into account safety systems and lead to obtain more realistic scenarios.     

Warning symbols as reminders of hazards: impact of training

Prior research indicates that many warning symbols are poorly understood. However Lesch [Lesch, M.F., 2003. Comprehension and memory for warning symbols: Age-related differences and impact of training. J. Safety Res. 34, 495–505] found that accident scenarios could be used to improve comprehension of warning symbols. The current study further investigated the potential benefits of accident scenario training. During training, warning symbols with verbal labels corresponding to the meaning of the symbol were paired with accident scenarios which expanded on the nature of the hazard, the required/prohibited actions, as well as the possible consequences of failing to comply. A number of measures were obtained prior to, and following (immediately and 2 weeks later), the accident scenario training: comprehension across three knowledge types (verbal label, required/prohibited actions, potential consequences of failure to comply), ratings of agreement with statements reflecting perceived control, and ratings of hazard and intent to comply. Benefits of training were observed on all dependent measures: Comprehension improved from 43 to 82% correct, reaction times were reduced by about 2 s, and level of confidence in correct responses increased by 23%. Ratings of perceived hazard, intent to comply, and perceived control over accident/injury involvement also increased. It is suggested that accident scenario training can be used to help prevent accidents and injuries by ensuring that responses to warnings are “sure and swift”.     

Looked-but-failed-to-see-errors in traffic

Danish studies of traffic accidents at priority intersections have shown a particular type of accidents. In these accidents a car driver supposed to give way has collided with a bicycle rider on the priority road. Often the involved car drivers have maintained that they did not see the bicycle until immediately before the collision even though the bicycle must have been clearly visible.

Similar types of accidents have been the subject of studies elsewhere. In literature they are labelled “looked-but-failed-to-see”, because it seems clear that in many cases the car drivers have actually been looking in the direction where the other parties were but have not seen (i.e. perceived the presence of) the other road user. This paper describes two studies approaching this problem.

One study is based on 10 self-reported near accidents. It does show that “looked-but-failed-to-see” events do occur, especially for well experienced drivers. The other study based on Gap Acceptance shows that the car driver acceptance of gaps towards cyclists depends on whether or not another car is present. Hypotheses for driver perception and for accident countermeasures are discussed.     

Statistical analyses of highway commercial vehicle accidentst†

In a research program aimed at the assessment of more comprehensive accident analysis methods, new applications of statistical analysis procedures to commercial vehicle accidents have been investigated, and exemplary results obtained [Philipson et al., 1978], A file of some 3000 specially-detailed California Highway Patrol accident reports from two areas of California during a period of about one year in 1975–1976 provided the unique data base for the application. Computer implementation and evaluation through statistical testing of the quality of the data file were first accomplished. Then an exhaustive univariate analysis of the data was conducted to describe the file in detail. Selected sets of dependent and independent variables were then subjected to analyses of association employing contingency table analysis methods. In several cases, acceptable log-linear models to explain the variables' association were thereby established. Vehicle exposure measured in vehicle miles traveled for each vehicle category was introduced into one of the analyses to assess its impact on the set of significant interactions; it was indeed found to be important, albeit accuracy in its estimation was problematical. This estimation was carried out by two independent methods; a “direct” procedure based on a series of linear extrapolations of basic State of California commercial vehicle traffic data, and an “induced” estimation procedure essentially employing only data in the accident reports. The results of the two methods exhibited some common trends, but otherwise differed considerably. The results of the research effort, highlighted in this article, indicated the value of the methods investigated, and so of the detailed accident report files necessary for their use. They also strongly illuminated the areas of greatest difficulty in the application of these methods, basically associated with accident data quality and exposure estimation accuracy, and general directions for their improvement.     

Prevention of timber felling and chainsaw-related accidents in the Republic of Ireland

A one-year prospective survey in four rural Irish counties was performed between January 1 and December 31, 1986, to analyse chainsaw accidents in a representative sample of domestic chainsaw users. Of the 62 accident cases recorded, the largest group were farmers, followed by a medley of self-employed “loggers” and domestic users. Every age group was represented, the commonest age group being 16–30 years. One of three female cases was an old-aged pensioner, and three other cases were aged under 12 years. Two of the latter cases had been using the saw when the accident occurred. Most injuries were sustained to the lower extremities, mostly due to a slip or misdirection of the saw. Of the 27 cases admitted to a hospital, 25 (93%) required surgical procedures with an average inpatient stay of eight days. Only 2 (3%) of the 62 cases wore an item of protective gear; in both cases, this was steel capped boots that were unsuitable for protection against chainsaw injuries. First aid at the accident site was very inadequate. The research indicates few of the cases were competent to use a power saw, and there was a general lack of appreciation of the risks associated with these implements and a disregard for safety procedures. While new forthcoming legislation on safety at work may improve safety standards in the future, a substantial proportion of chainsaw users in Ireland are currently at risk from further accidents.     

Centering of the ion trajectory in the cyclotron

In this paper we present the theory of the horizontal motion ions through the acceleration gap in the case of a static magnetic field and time-varying electric field. It also describes the motion of the center of the ion trajectory through the acceleration gap and also during the acceleration process. The result also describes analytically the angle through which the ion passed (so called “flying angle”) between two acceleration gaps. That angle can be measured from the center of the ion trajectory or from the center of the cyclotron. The analysis shows that the “flying angle” of the ions measured in these two reference systems is not same. Namely, the “flying angle” of the ion measured from the center of its trajectory is bigger than in the case when the “flying angle” is measured from the center of the cyclotron. It shows that difference between “flying angle” in these two reference systems becomes less and less during acceleration process.     

Development of a framework for the risk assessment of Na-Tech accidental events

Natural events impacting on chemical and process plants may cause severe accidents, triggering the release of relevant quantities of hazardous substances. The present study focused on the development of the tools needed to build up a general framework allowing the extension of quantitative risk assessment procedure to include the analysis of the industrial accidents caused by natural events. Specific methods and models were developed to allow the quantitative assessment of risk caused by two categories of “Na-Tech” accidents: accidents triggered by earthquakes and accidents triggered by floods. The approach allows the identification of the different damage modes expected for process equipment and of the accidental scenarios that may be triggered. The damage models developed allow the calculation of the damage probability of equipment items due to the natural events. A specific methodology was issued to take into account the consequences of the possible contemporary failure of several process units due to the impact of the natural event. The procedure allows the calculation of the overall individual and societal risk indexes including the multiple-failure scenarios caused by the impact of natural events. The overall methodology was applied to the analysis of specific case studies.     

A macroscopic impact analysis of the safety efforts case study: Pedestrian fatalities

Any time there are reductions in accidents, advocates of any particular position are quick to claim that it is their “effect” that has improved safety performance. The work in this paper focuses on interpreting a traffic system's performance with respect to a specific type of accident by attributing a change in the number of accidents to the relative contribution of three effects: the activity effect, the safety content effect, and the structure effect. A method is developed and applied to the data sets of pedestrian fatalities that occured in Greece during the period of 1965–1989. The relative contribution of the effects as well as the pattern changes turn out to have a decisive influence. The possible uses and extensions of the method are also discussed.     

On the prevention of accidents and injuries : A comparative analysis of conceptual frameworks

The meaning of prevention has changed as new applications of the concept have appeared. Ideas presented in eleven different conceptual frameworks are compared. Identification of the frameworks took place through searches in databases and relevant literature. Five are general by nature, while six relate to injuries and accidents. All are supported by just a few parameters, the time dimension being the most prominent. Compatibility was established on three additional dimensions: level (individual, organizational or societal); direction (“bottom-up” or “top-down”); and in relation to the trichotomy “host-agent-environment”. An attempt to synthesize all these dimensions into one general model of accident and injury prevention is presented.     

Comparison groups in road safety studies: An analysis

When the safety effect of some treatment is to be estimated, one has to answer the question: “what would have been the ratio of the expected number of accidents ‘before’ and ‘after’ had the treated group been left without treatment? ” In retrospective observational studies, the count of accidents on a “comparison group” is often used to provide an answer. In consequence, the estimate of the safety effect depends on which of several comparison groups is chosen. It is therefore important to have guidance for this choice. The empirical inquiry in the companion paper led to several conclusions. The explanation of what has been noted by the examination of data requires analysis and is taken up in this paper.     

A typology for drinking driving offenders: Methods for classification and policy implications

Comprehensive arrest histories were obtained for 353 DUI offenders who were referred to a probation and rehabilitation demonstration program. The average number of total offenses was 7.9, with 89% of all tracked offenders having more than one offense. Approximately 63% of all recorded offenses were other types of offenses besides DUI. The overall arrest history profile of the group suggested that many DUI offenders are habitual violators of other laws as well. To identify distinctive arrest profiles within the referral sample, a Q mode factor analysis followed by a discriminant function analysis was used to classify offenders into profile subgroups. Five distinctive subgroups emerged. A “low offense” group was characterized by the lowest average number of overall arrests and also contained all offenders with no arrest besides the index DUI arrest. A “mixed” group had a higher average number of total arrests than the “low offense” group and diverse types of offenses. A young “traffic” group was distinguished by many hazardous moving violations other than DUI. Two smaller and older groups—a “public drunkenness” group and a “license” group—had the highest average number of arrests including DUI, public drunkenness, license violations, equipment violations, disturbance arrests and assault arrests. These subgroups were found to differ on demographic variables and drinker status variables. The “public drunkenness” group was found to have the highest accident rate. Groups were compared to groups found in other cluster analyses. Also, treatment implications were discussed. It was suggested that treatment programs focusing exclusively on changing alcohol consumption behavior are not likely to reduce accident risk for some of the offender groups. For example, it was suggested that effective intervention for the “traffic” group should target driving behavior, whether drunk or sober, rather than focus exclusively on consumption behavior. Other alternatives are also discussed.     

Measuring accident risk exposure for pedestrians in different micro-environments

Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the concept of risk exposure used in environmental epidemiology, such as in the case of exposure to pollutants. This type of indicator would be useful for comparing the effects of urban transportation policy scenarios on pedestrian safety. The first step is to create an indicator of pedestrians’ exposure, which is based on motorised vehicles’ “concentration” by lane and also takes account of traffic speed and time spent to cross. This is applied to two specific micro-environments: junctions and mid-block locations. A model of pedestrians’ crossing behaviour along a trip is then developed, based on a hierarchical choice between junctions and mid-block locations and taking account of origin and destination, traffic characteristics and pedestrian facilities. Finally, a complete framework is produced for modelling pedestrians’ exposure in the light of their crossing behaviour. The feasibility of this approach is demonstrated on an artificial network and a first set of results is obtained from the validation of the models in observational studies.