A new simple methodology for evaluation of explosion risk in underground coal mines

The key objective of this paper is the presentation of a new risk assessment tool for underground coal mines based on a simplified semi-quantitative estimation and assessment method.In order to determine the risk of explosion of any work process or activity in underground coal mines it is necessary to assess the risk. The proposed method is based on a Risk Index obtained as a product of three factors: frequency of each individual scenario P_ucm, associated severity consequences C_ucm and exposure time to explosive atmospheres E_ucm. The influence of exposure time is usually not taken into account up to now. Moreover, the exposure to explosive atmospheres may affect factors of hazardous event probability as much as its consequences. There are many definitions of exposure to explosive atmospheres but in the case of underground coal mines the exposure is defined as frequency risk of firedamp and coal dust. The risk estimation and risk assessment are based on the developed of a risk matrix.The proposed methodology allows not only the estimation of the explosion risk but also gives an approach to decide if the proposal investment is well-justified or not in order to improve safety.     

Quantification of risk perception: Development and validation of the construction worker risk perception (CoWoRP) scale

Introduction: The construction sector is leading in the number of accidents and fatalities; risk perception is the key to driving these numbers. Previous construction safety studies on risk perception quantification have not considered affective risk perception of construction workers or conducted comprehensive reliability and validity testing. Thus, this study aims to fill this need by developing a psychometrically sound instrument – the Construction Worker Risk Perception (CoWoRP) Scale – to assess the risk perception of construction workers. Method: Four phases of scale development, namely, item development, factor analysis, reliability assessment, and validity assessment were conducted with the collection and testing of data from a group (n = 469) of voluntary construction workers in Hong Kong. Results: The CoWoRP Scale with 13 items was shown to have acceptable test–retest reliability, internal consistency reliability, as well as content, convergent, discriminant, and criterion-related validity. Also, the CoWoRP Scale was affirmed to have three dimensions of worker risk perception, namely risk perception – probability, risk perception – severity, risk perception – worry and unsafe. These three dimensions of worker risk perception were negatively correlated with their risk-taking behavior. Conclusions: The CoWoRP Scale is a reliable and valid instrument for measuring the risk perception of construction workers and is expected to facilitate the construction safety studies that take risk perception of construction workers into account. Practical applications: The CoWoRP Scale could serve as an aptitude test to identify the characteristics of construction workers most likely to perceive lower risk in risky work situations. In turn, this information could help safety management provide safety training programs to those workers to enhance their risk perception and thereby minimizing their risk-taking behavior, reducing unnecessary training costs, and improving the construction safety performance.     

Modeling crash severity by considering risk indicators of driver and roadway: A Bayesian network approach

Introduction: Traffic crashes could result in severe outcomes such as injuries and deaths. Thus, understanding factors associated with crash severity is of practical importance. Few studies have deeply examined how prior violation and crash experience of drivers and roadways are associated with crash severity. Method: In this study, a set of risk indicators of road users and roadways were developed based on their prior violation and crash records (e.g., cumulative crash frequency of a roadway), in order to reflect certain aspect or degree of their driving risk. To explore the impacts of those indicators on crash severity and complex interactions among all contributing factors, a Bayesian network approach was developed, based on citywide crash data collected in Kunshan, China from 2016 to 2018. A variable selection procedure based on Information Value (IV) was developed to identify significant variables, and the Bayesian network was employed to explicitly explore statistical associations between crash severity and significant variables. Results: In terms of balanced accuracy and AUCs, the proposed approach performed reasonably well. Bayesian modeling results indicated that the prior crash/violation experiences of road users and roadways were very important risk indicators. For example, migrant workers tend to have high injury risk due to their dangerous violation behaviors, such as retrograding, red-light running, and right-of-way violation. Furthermore, results showed that certain variable combinations had enhanced impacts on severity outcome than single variables. For example, when a migrant worker and a non-motorized vehicle are involved in a crash happening on a local road with high cumulative violation frequency in the previous year, the probability for drivers suffering serious injury or fatality is much higher than that caused by any single factor. Practical applications: The proposed methodology and modeling results provide insights for developing effective countermeasures to reduce crash severity and improve traffic system safety performance.     

基于模糊保护层的池火灾事故风险分析

为计算引发池火灾事故的风险值,提高事故风险的量化水平,判断现有风险控制措施是否满足风险容忍度的要求,为制定减缓风险措施提供依据,给出了新的池火灾风险评估模型。基于传统的保护层分析模型(LOPA),结合模糊集合理论,引入模糊风险矩阵进行风险评估,构建适用于引发池火灾事故的模糊保护层(fL OPA)风险分析模型。该模型的特点是将模糊逻辑和保护层分析结合,减少了传统保护层分析方法计算过程中的不确定性因素,引入严重度减少指数(SRI)概念,使严重度计算、风险评估更加准确。运用该模型对原油储罐泄漏池火灾事故风险进行分析,给出风险决策方案,判断现有保护措施是否能控制风险在可容忍范围内,实例验证了模型的可行性。     

基于风险矩阵的水电站项目风险分级评估方法研究——以乌东德水电站为例

为了解决千万千瓦级巨型水电站项目建设过程的风险分析问题,以我国目前在建的千万千瓦级水电站重要项目—乌东德水电站为例,对水电站项目存在的隐患进行排查和梳理,找出影响安全施工的危险源,并采用风险矩阵法对其进行风险评估,将存在的风险按照其造成的影响后果不同分成可忽略（Ⅰ级）、可接受（Ⅱ级）、有条件可接受（Ⅲ级）和不可接受（Ⅳ）4个等级。研究结果不仅可用于查找、分析整个水电站项目建设过程中存在的重大风险,对风险进行有效、科学、简捷地评估,还可将各个风险点进行明确划分,对同类千万千瓦级巨型水电站的风险分析和安全管理工作具有参考和借鉴作用。     

The role of risk perception and other risk-related judgements in transportation mode use

AimsThe core aim of the present study was to examine the role of risk perception in use of private and public modes of transportation. An additional aim was to examine the relative importance of perception of transport risks with risk perception of non-transport factors and also to investigate differences in worry, perceived control of transportation modes, as well as trust in authorities’ risk handling, safety motivation, and attitudes towards transport safety.SampleThe results are based on a mailed self-completion questionnaire survey carried out among a representative sample of the Norwegian public aged from 18 to 65 years (n = 1864). Data collection was carried out during October–December 2008.ResultsPerceived control related to private modes of transportation, knowledge about safety and trust in authorities were found to be significantly different among respondents who often used private modes of transportation compared to those who most often used public modes. It was no significant difference in severity of consequences due to which transport modes that the respondents used most frequently.ConclusionIt may be that conclusions of previous research about the role of consequence judgement for precautionary action and demand for risk reduction are misleading when generalised to decisions about transport mode use.     

Workplace bullying in risk and safety professionals

IntroductionPrevious research demonstrates that workplace bullying impacts the welfare of victimized employees, with further consequences for the organization and profession. There is, however, a paucity of information relating to the bullying directed at risk and safety professionals. The present study was conducted to address this issue.MethodRisk and safety professionals (N = 420) completed the Negative Acts Questionnaire – Revised and Brief Cope, and reported the extent to which they had been pressured to make or amend a risk or safety based decision.ResultsThose experiencing workplace bullying were more likely to engage in a range of coping behaviors, with exposure to work-related and personal bullying particularly influential. Workplace bullying also predicted pressure to make or change a risk or safety based decision. Work related and physically intimidating bullying were particularly important for this aspect of professional practice.ConclusionsFindings are discussed with regard to current practice and the support available to risk and safety professionals.Practical applicationsRisk and safety professionals require additional support in relation to workplace bullying and specifically guidance to resist pressure to make or change a risk or safety based decision.     

基于风险等值线的职业安全评价分级方法

依据危害因素引发工伤、职业危害事件的后果严重度和可能性来开展职业安全评价,在严重度和可能性的定量评价基础上,引入等值风险线的概念,建立风险评价分级方法,并在单一危害因素的职业安全评价基础上建立了作业场所、工厂、企业的职业安全(风险)评价分级方法.通过应用实例分析,验证了该方法的可操作性.     

The insurance market’s influence on investments in safety measures

In a risky process there are three alternative ways to treat the negative consequences of the risk or the accident. We can: (1) take all the consequences when an accidental event occurs, (2) reduce the probability and/or the consequences of an accidental event by safety measures or (3) transfer the consequences of the occurrence to parties better able to carry them (i.e. buying insurance). In safety management a prevailing practice is that access to an insurance market does not affect the investment in safety measures. In this paper we discuss what the consequences are of this common practice in relation to insurance and mandatory safety requirements. We conclude that an overinvestment in safety measures is very likely if insurance is not taken into account. Moreover, mandatory safety measures and insurance can lead to both over- and underinvestment in safety measures.     

How to treat expert judgment? With certainty it contains uncertainty!

To be acceptably safe one must identify the risks one is exposed to and decide what risk reducing measures are required. It is uncertain whether the threat really will materialize, but determining the size and probability of the risk is also full of uncertainty. When performing an analysis and preparing for decision making under uncertainty, quite frequently failure rate data, information on consequence severity or on a probability value, yes, even on the possibility that an event can or cannot occur, is lacking. In those cases, a possible way and sometimes the only way to proceed is to revert to expert judgment. Even in case historical data is available, an expert can be asked whether and to what extent such data still hold in the current situation.Anyhow, expert elicitation comes with an uncertainty depending on the expert's reliability, which becomes very visible when two or more experts give different answers or even conflicting answers. This is not a new problem, and very bright minds have thought how to tackle this in a rational and objective way. But so far, however, the topic has not been given much attention in daily process safety and risk assessment practice. Therefore, this paper has a review and applied character and will present various approaches with detailed explanation and examples.     

Differences in risk perception,priorities, worry and demand for risk mitigation in transport among Norwegians in 2004 and 2008

The present study aimed to investigate differences in risk perception, the demand for risk mitigation, priorities and worry related to transport among the Norwegian public in 2004 and 2008. Age, gender, education, driver licence and number of injuries in transport were controlled for. The comparison was carried out with questionnaire surveys among representative samples of the Norwegian public in 2004 (n = 1730) and 2008 (n = 1864). The results showed that the perceived probabilities of transport accidents decreased, whereas the perceived severity of consequences increased during this period. Both samples estimated higher probabilities of accidents by private means of transport. The demand for risk mitigation and priorities related to transport safety increased significantly in the same period. The 2008 sample also reported more worry regarding accidents by private transport. Results were discussed in relation to transport safety campaigns, safety measures and significant accidents which occurred in this period.     

Does longevity impact the severity of traffic crashes? A comparative study of young-older and old-older drivers

Introduction: This article analyzes the effect of driver’s age in crash severity with a particular focus on those over the age of 65. The greater frequency and longevity of older drivers around the world suggests the need to introduce a possible segmentation within this group at risk, thus eliminating the generic interval of 65 and over as applied today in road safety data and in the automobile insurance sector. Method: We investigate differences in the severity of traffic crashes among two subgroups of older drivers –young-older (65–75) and old-older (75+), and findings are compared with the age interval of drivers under 65. Here, we draw on data for 2016 provided by Spanish Traffic Authority. Parametric and semi-parametric regression models are applied. Results: We identified the factors related to the crash, vehicle, and driver that have a significant impact on the probability of the crash being slight, serious, or fatal for the different age groups. Conclusions: We found that crash severity and the expected costs of crashes significantly increase when the driver is over the age of 75. Practical Applications: Our results have obvious implications for regulators responsible for road safety policies – most specifically as they consider there should be specific driver licensing requirements and driving training for elderly – and for the automobile insurance industry, which to date has not examined the impact that the longevity of drivers is likely to have on their balance sheets.     

The effect of speed limit reductions in urban areas on cyclists’ injuries in collisions with cars

Abstract

Objective: Impact speed is one of the most important factors explaining the severity of injuries to cyclists when they collide with passenger cars. To reduce injury severity (especially for vulnerable road users), since 2008, Swedish municipalities have the authority to lower the speed limit to 30 or 40?km/h in urban areas as appropriate. The aim of this study was to evaluate how this speed limit reduction has influenced the injury severity for cyclists in this type of collision.

Method: Data from 1,953 collisions between bicycles and passenger cars were collected using information from third-party-liability insurance claims from 2005 to 2017. The change of speed limit distribution, influenced by the reduction of speed limits in urban areas, where car-to-cyclist collisions occurred was studied. Following that, injury severity for cyclists was evaluated regarding collisions occurring in areas with different speed limits.

Results: The results show that, in collisions with cars, cyclists have a significantly lower risk of a moderate-to-fatal (MAIS 2+) injury when the speed limit is 30–40?km/h compared to 50–60?km/h. During the last decade, while the speed-limit has been lowered on many road-sections in urban areas from 50–60?km/h to 30–40?km/h the risk of a cyclist getting a MAIS 2+ injury decreased by 25%. In 2005 to 2011, 16% of the crashes happened on a road with a speed limit of 30–40?km/h; in 2016–2017, this percentage had increased to approximately 50%. Thus, in recent years more crashes occurred on roads with lower speed limits, and in these crashes, there was a lower risk of severe injuries to cyclists. Unfortunately, it was not possible to evaluate the risk of a crash for specific speed limits; since one limitation of this study was the lack of exposure data, nor do we know the impact speed or the actual speed of the vehicles.

Conclusions: This study is an important follow-up on the implementation of measures that can influence bicycle safety. The insurance data used, made it possible to quantify a positive effect on injury severity for cyclists in passenger car-to-cyclist collisions when the speed limit was reduced in urban areas. Insurance claims cover collisions of all crash severity, so they include data covering all types of injuries—not just the most severe/fatal ones. This aspect is especially important in the speed intervals evaluated here, since moderate (MAIS 2) injuries are very frequent in lower-speed crashes and even these injuries can result in long-term consequences.     

3-Parameters SPW technique: A new method for evaluation of target safety integrity level

Introduced by IEC-61508 standard, safety integrity levels (SIL) have been used for assessing the reliability of safety instrumented functions (SIF) for protection of the system under control in abnormal conditions. Different qualitative, semi-qualitative and quantitative methods have been proposed by the standard for establishing target safety integrity levels amongst which “Risk Graph” has gained wide attention due to its simplicity and easy-to-apply characteristics. However, this method is subject to many deficiencies that have forced industry men and experts to modify it to fit their demands. In this paper, a new modification to risk graph parameters has been proposed that adds more flexibility to them and reduces their subjective uncertainties but keeps the method as simple as before. Three parameters, namely severity (S), hazard avoidance probability (P), and demand rate (W) are used instead of former four parameters. Hence, the method is named SPW. The outcome results of this method can be directly converted to probability of failure on demand (PFD) or risk reduction factor (RRF). The proposed method has been tested on an example case that has been studied before with conventional risk graph and LOPA techniques. The results show that new method agrees well with LOPA and reduces costs imposed by conservative approximations assumed during application of conventional risk graph.     

Application of dynamic risk analysis in offshore drilling processes

Process safety is the common global language used to communicate the strategies of hazard identification, risk assessment and safety management. Process safety is identified as an integral part of process development and focuses on preventing and mitigating major process accidents such as fires, explosions, and toxic releases in process industries. Accident probability estimation is the most vital step to all quantitative risk assessment methods. Drilling process for oil is a hazardous operation and hence safety is one of the major concerns and is often measured in terms of risk. Dynamic risk assessment method is meant to reassess risk in terms of updating initial failure probabilities of events and safety barriers, as new information are made available during a specific operation. In this study, a Bayesian network model is developed to represent a well kick scenario. The concept of dynamic environment is incorporated by feeding the real-time failure probability values (observed at different time intervals) of safety barriers to the Bayesian network in order to obtain the corresponding time-dependent variations in kick consequences. This study reveals the importance of real-time monitoring of safety barrier performances and quantitatively shows the effect of deterioration of barrier performance on kick consequence probabilities. The Macondo blowout incident is used to demonstrate how early warnings in barrier probability variations could have been observed and adequately managed to prevent escalation to severe consequences.     

大坝安全评价的可接受风险研究与评述

评述了国内外安全领域可接受风险研究的历史和现状.根据事故后果对风险进行分类,对不同类型风险给出风险定量表示方法,针对不同的风险定量表示方法,应用F-N曲线和ALARP准则研究相应的可接受风险确定方法,并就其在大坝安全风险评价领域的应用进行探讨.     

基于Bowtie模型的机场安全风险分析

运用Bowtie模型对隐患、可能的事故原因以及后果进行评判,分析重点放在风险控制和组织控制的薄弱环节上。利用Bowtie模型,分析机场安全风险,以跑道侵入事件为算例进行深入分析,探讨影响机场安全风险的组织因素。量化影响跑道侵入的结构重要度,计算不同阶段、不同条件下,可能导致跑道侵入事件发生的概率。从风险管理和组织安全的角度,预防跑道侵入事件的发生提供理论依据和实际指导。     

基于模糊数学的石油化工装置HAZOP风险分析技术研究

对传统的HAZOP分析中偏差原因发生可能性进行量化。对于有统计数据的,根据行业数据、公司经验及企业事故建立HAZOP风险分析统计数据库;对于没有统计数据的HAZOP分析偏差原因发生概率,通过专家主观评判,用模糊数理论将专家自然语言转换为模糊数,采用左右模糊排序法将模糊数转换为模糊失效概率值。研究了偏差后果严重程度的划分标准,并根据偏差原因概率和偏差后果严重程度确定风险等级,利用风险矩阵得出偏差风险的大小。从而把HAZOP分析方法从定性改进为半定量的分析方法。据此对石油化工装置进行了HAZOP风险分析。     

On the ontological status of the concept of risk

In this paper we review a set of frequently used risk definitions and analyze their ontological status, i.e. to what extent risk exists in itself independent of any specific assessor. According to some prevailing risk perspectives in the social sciences, risk exists as objective states of the world, but for other common risk perspectives the status of risk is not as clear, for example if risk is viewed as uncertainty about and severity of the consequences of an activity with respect to something that humans value. The principal aim of this paper is to contribute to a clarification of the issue in order to strengthen the foundations of the meaning of risk.     

Thermal hazard analysis of triacetone triperoxide (TATP) by DSC and GC/MS

Thermal degradation of triacetone triperoxide (TATP) was studied using differential scanning calorimetry (DSC) and gas chromatography/mass spectrometry (GC/MS). TATP, a potential explosive material, is powerful organic peroxide (OP) that can be synthesized by available chemicals, such as acetone and hydrogen peroxide in the laboratory or industries. The thermokinetic parameters, such as exothermic onset temperature (T₀) and heat of decomposition (ΔH_d), were determined by DSC tests. The gas products from thermal degradation of TATP were identified using GC/MS technique.In this study, H₂O₂ was mixed with propanone (acetone) and H₂SO₄ catalysis that produced TATP. The T₀ of TATP was determined to be 40 °C and E_a was calculated to be 65 kJ/mol. A thermal decomposition peak of H₂O₂ was analyzed by DSC and two thermal decomposition peaks of H₂O₂/propanone were determined. Therefore, H₂O₂/propanone mixture was applied to mix acid that was discovered a thermal decomposition peak (as TATP) in this study. According to risk assessment and analysis methodologies, risk assessment of TATP for the environmental and human safety issue was evaluated as 2-level of hazard probability rating (P) and 6-level of severity of consequences ratings (S). Therefore, the result of risk assessment is 12-point and was evaluated as “Undesirable” that should be enforced the effect of control method to reduce the risk.