Risk informed optimization of a hazardous material multi-periodic transportation model

This paper presents a systematic framework toward the development of a Transportation Model for Hazardous Materials (HazMat). In practice, the proposed modeling framework is realized through an appropriate generalization of the traditional transportation network problem in the presence of safety constraints that need to be satisfied. The objective is to minimize transportation cost while reducing risks at the desired levels.In particular, the present research study identifies and evaluates different risk factors that influence the HazMat transportation network. Next, the transportation model is depicted graphically using nodes and arcs and optimal conditions are identified by solving the associated minimum cost flow network problem. The results show safety levels that help making informed decisions on choosing the optimal transportation configuration for hazardous material shipments.Within the proposed methodological context, appropriately parameterized simulation studies elucidate the effects of occurrence probabilities of the different risk events on transportation cost. Furthermore, as the appropriate management decisions must consider the effect of actions in one time period on future periods, the proposed model is structured as a multi-periodic model.Finally, the proposed methodological approach is employed to demonstrate the utility of proper analytical tools in decision making and particularly in ensuring that scientifically informed safety procedures are in place while transporting goods that can be potentially proven dangerous to the public and the surroundings.     

时变条件下公路危险品罐车运输路线选择

为合理选择公路运输危险品路线,保障运输安全,将用于求解静态路径规划问题的Diikstra标号法进行推广和改进,提出指标累积值标号法,运用该方法并依据危险品罐车运输事故统计数据,建立了时变条件下以路段泄漏事故率、路侧人口密度及路段运输费用为指标的危险品罐车公路运输路线选择模型.并给出待选路线对比原则.实例应用表明,该模型充分考虑了事故概率、事故后果及运输成本3大危险品运输路线选择影响因素,使用方便且受主观因素影响小,具有较好的实用性.     

危险品道路运输选线问题分析

从运输网、运输危险源、影响区域3方面提出了危险品道路运输风险分析的框架.将道路固有特征、气象条件、交通状况和人口密度分布等风险减缓或扩大因素划分为8类,重点讨论了主要路线的自变量和因变量因素.采用双层选线管理模式,深入分析了最小化运输事故概率和暴露人口风险模型.应用权数调整节点标号算法和边线标号算法解决危险品道路运输选线问题.对影响区暴露人口的选取做了深入探讨,考虑了邻接交迭路段暴露人数的误差,对准确计算危险品运输风险有重要价值.     

Trends of hazardous material accidents (HMAs) during highway transportation from 2013 to 2018 in China

Statistical analysis of hazardous material accidents (HMAs) in China from 20013 to 2018 related to characteristics and consequences is discussed in this study, revealing different time volatility, spatial distribution and accident consequence features. Yearly, monthly, weekly and hourly levels of HMAs are analysed, and the corresponding factors are discussed. The trends of HMAs are affected by different factors, such as efforts toward safety-specific rectification by the government, holidays, five-day workweek systems and daily traffic peaks. The spatial distribution trends indicate that highway transportation of hazardous materials is mostly short-distance transport. The accidents that occurred on normal road sections account for 82.76% of the total HMAs during transportation. Leaking accidents caused by HMAs account for 79.35% of the total accidents. Countermeasures focusing on improving highway transportation safety for hazardous materials are recommended.     

零星危险化学品快递运输风险博弈分

针对零星危险化学品运输中的安全隐患问题,应用博弈理论构建了政府、快递企业、零星危险化学品托运人的三方博弈模型,对零星危险化学品安全运输问题进行了研究。在求得博弈模型均衡解的基础上,对均衡解进行了深入分析,研究结果表明:政府的最优检查概率与快递企业的安全管理成本正相关,与快递企业发生事故时的损失负相关;快递企业实施安全管理的概率与政府对快递企业的惩罚、快递企业发生事故时政府的损失正相关,与政府的检查成本、托运人选择托运且安全运输时的收益负相关;托运人选择托运的概率与快递企业实施安全管理的成本正相关。最后为有效杜绝零星危险化学品运输事故的发生提出了相应对策。     

交通信息下危险品道路运输动态路径选择研究

根据影响危险品道路运输路径选择的风险、经济及时间因素,构建了包含风险、经济及时间的广义运输时间函数.将出行者对路段的广义运行时间预测看作随机过程,对出行路径上节点到达广义时间取期望值,利用一阶近似,建立基于广义时间最短的动态路径选择模型.研究表明,在交通信息可获知条件下,只要给定起讫点对(Origin-Destination,简称OD)中起点的出发时间,就可通过基于广义时间最短的动态路径选择模型求解通过某一路径到达终点的期望时间,而最小期望时间所对应路径即是危险品道路运输动态最短路径.     

危险品航空运输事故的改进贝叶斯网络分析

以危险品航空运输事故树为基础,建立了贝叶斯网络(BN).运用贝叶斯原理以及推理计算,找出了危险品航空运输事故的主要致因,并分析了改进措施对危险品航空运输系统的影响程度.结果表明,引进改进措施后,事故一发生就已经超出可控范围的后验概率最大,将成为预防危险品航空运输事故的工作重点.研究表明,风险评价领域中的贝叶斯网络分析法是对事故树方法的有益改进.     

STAMP模型在危化品道路运输事故分析中的应用研究

为保障危化品道路运输行车安全,基于STAMP模型构建危化品道路运输的分层安全控制结构,将安全问题看作是控制问题,并将系统工程思想融入事故预防中。在此基础上,引入沪昆高速湖南邵阳段“7.19”特别重大道路交通危化品爆燃事故并对其进行实证分析,从物理层、基础层、运营层及监管层动态分析导致事故发生的控制缺失。结果表明:基于STAMP模型的安全分析方法不仅可考虑由组件失效引起的事故,还可发现组件之间的组织问题及决策背景,并对事故致因做出更为详细的解释,为类似事故的分析和预防提供思路与参考。     

Analysis of factors that influence hazardous material transportation accidents based on Bayesian networks: A case study in China

In this study, we applied Bayesian networks to prioritize the factors that influence hazardous material (Hazmat) transportation accidents. The Bayesian network structure was built based on expert knowledge using Dempster-Shafer evidence theory, and the structure was modified based on a test for conditional independence. We collected and analyzed 94 cases of Chinese Hazmat transportation accidents to compute the posterior probability of each factor using the expectation-maximization learning algorithm. We found that the three most influential factors in Hazmat transportation accidents were human factors, the transport vehicle and facilities, and packing and loading of the Hazmat. These findings provide an empirically supported theoretical basis for Hazmat transportation corporations to take corrective and preventative measures to reduce the risk of accidents.     

基于多商品流理论与成本效益分析的公路危险品运输路径优化研究

风险是危险品运输区别与普通货物运输的基本要素,因此,危险品运输既要实现经济目标,又要满足安全的需要。危险品运输其路径优化问题的关键在于在经济性与安全性间取得平衡。为此,在运输成本与风险值间引入权重参量,并充分考虑到路网容量及个别路段最大期望风险等限制因素,运用多商品流理论建立了基于运输成本和运输风险最小化的双目标路径优化模型。进一步地,运用成本效益分析法,并从全局角度对不同解所对应的路径优化方案进行比较,提出了相应的比选准则。最后,通过算例分析证明了该方法的有效性。     

A transportation network assessment tool for hazardous material cargo routing: Weighing exposure health risks,proximity to vulnerable areas,delay costs and trucking expenses

The inherent risks associated with accidental releases of hazardous materials during transport have drawn attention and concerns in the recent decades. The aim of this study is to propose a tool for evaluation and comparison of the transportation networks which can be used to assess the routing options between origins and destinations of the cargos for their suitability for transporting hazardous material cargos by tanker trucks and to identify routes which provide lower accidental release risks, lower public exposure risks, and offer economical benefits. Each route segment of transportation networks were evaluated using specific criteria which included health risk and cost of delay in case of an accidental release of materials, trucking cost and proximity to vulnerable areas. Since, the health impact of hazardous materials differ depending on the characteristics of the material being transported as well as release quantities and atmospheric conditions; this paper aimed in providing a tool that can be used to estimate the impact radius (for health risks) after accidental release of hazardous materials by taking into account different atmospheric conditions based on the meteorological data and solar elevation angle. The Gaussian air dispersion model paired with ArcGIS using Python programming were employed to estimate the health risk impact zones by considering the meteorological data, and accordingly to analyze road segments for cost impacts (delay and trucking costs), and the proximity to vulnerable areas. The route assessment tool was demonstrated with a case study. The results of this study can efficiently aid decision makers for transportation of hazardous materials.     

Insights into process safety incidents from an analysis of CSB investigations

Many incidents have helped to define and develop process safety. Each has provided valuable learning opportunities. However, it is even more important to identify insights that can be obtained from an analysis of a large set of incidents that represents those that typically occur. This larger picture illuminates trends and commonalities and provides learning opportunities that are even more important than the causes of any one individual incident.The Chemical Safety Board has published the results of over 60 investigations of process safety incidents. These data have been analyzed to identify commonalities and trends so that measures to help protect against future incidents can be developed. Recommendations are made to address key issues identified.     

基于火灾监控视频的人员疏散行为统计分析

火灾中人员的疏散行为是一个极为复杂的过程,受到众多外界刺激的干扰。通过对某真实火灾监控视频中人员疏散行为的统计分析,还原了火灾现场部分人员从发现火灾、观望等待、准备撤离到安全疏散全过程的心理状态,以及疏散过程中典型外界刺激对人员疏散心理状态的改变,提出火灾中听觉刺激对人员产生的心理冲击最为强烈,直接影响了人员疏散行为的实施。疏散过程中样本人群还表现出典型的羊群效应。     

Dangerous good transportation by road: from risk analysis to emergency planning

Despite the relative recent move towards inherent safe materials, the relentless drive of consumerism requires increased quantities of dangerous goods to be manufactured, transported, stored and used year on year. The safety and effectiveness of road transport systems is to be considered a strategic goal in particular in those countries, like Italy, in which 80% of goods are transported by this means. In this paper, we face the risk from dangerous good transport by presenting a site-oriented framework for risk assessment and developing a theoretical approach for emergency planning and optimisation. In the first step, we collected field data on a pilot highway and developed a database useful to allow a realistic evaluation of the accident frequency on a given route, by means of multivariate statistical analysis. To this end, we considered both inherent factors (such as tunnels, bend radii, height gradient, slope etc), meteorological factors, and traffic factors (traffic frequency of tank truck, dangerous good truck etc.) suitable to modify the standard national accident frequency. By applying the results to a pilot area, referring to flammable and explosive scenarios, we performed a risk assessment sensitive to route features and population exposed. The results show that the risk associated to the transport of hazardous materials, in some highway stretches, can be at the boundary of the acceptability level of risk set down by the well known F/N curves established in the Netherlands. On this basis, in the subsequent step, we developed a theoretical approach, based on the graph theory, to plan optimal emergency actions. The effectiveness of an emergency planning can normally be evaluated in term of system quickness and reliability. As a case study, we applied the developed approach to identify optimal consistency and localisation in the pilot area of ‘prompt action vehicles’, properly equipped, quick to move and ready for every eventuality. Applying this method results in an unambiguous and consistent selection criterion that allows reduction of intervention time, in connection with technical and economic optimisation of emergency equipment.     

Developing a chaotic pattern of dynamic risk definition for solving hazardous material routing-locating problem

In the case of determining routes and locations for constructing distribution centers on hazardous materials (Hazmat) transportation, risk and cost are considered as the main attributes for developing mathematical models. Since, Hazmat transport risk may be defined as a chaotic factor, using dynamic risk changes the selected routes and optimized locations for constructing distribution centers.In the present paper, an iterative procedure has been proposed to determine the best routes and optimized locations of distribution centers for transporting hazardous materials based on the concept of chaos theory in which hazmat transport risk is defined as a dynamic variable. A mathematical model has been developed for solving Hazmat routing and locating problems, simultaneously. Daily transport risk, defined as a chaotic variable, is iteratively updated using one-dimensional logistic map equation over the time period (year). An experimental road network, consists of eighty nine nodes and one hundred and three two-way edges, has been selected for analytical process and model validation. Results revealed that although different amounts of risk and cost priorities change optimized locations of distribution centers and their associated supplies, but the most frequent set of optimized centers remains independent. Therefore, the proposed procedure is capable to determine the best routes and optimized locations for distributing hazardous materials. While risk is iteratively updated over a specific time period, results show that the main property of chaos theory known as dependency upon initial condition would not be a serious concern for decision makers who are dealing with Hazmat management.     

An integrated approach to the analysis of incident causes

Root cause analysis (RCA) is a well-established method for the determination of incident causes. However, the application of the method, especially for accidents in complex socio-technical systems, encounters limitations. It cannot identify some types of causes. This article finds ways to deal with the limitations, and integrates them into the RCA procedure. It results in the proposal of the Integrated Procedure of Incident Cause Analysis (IPICA). The integrated approach is based on the integration of assumptions about the structure of safety management in the investigated process into a comprehensive picture. It offers an integrated view of various types of causes. To a necessary extent, it integrates a non-linear incident model into the RCA procedure. The example – an analysis of the Walkerton tragedy from 2000 – illustrates the application of the integrated approach. IPICA is shown to be more universal than RCA, just as effective, and not excessively complicated.     

放射性材料运输事故泄漏概率分析

根据放射性材料运输事故过程探讨了放射性材料道路运输导致放射性泄漏污染事故的风险评价模型,基于运输事故统计数据和事故载荷环境严重度分类建立了放射性材料运输泄漏事故发生率的定量评估方法.应用结果表明,该方法能对放射性材料运输泄漏事故概率进行初步定量估算.     

The acceleration of flames in tube explosions with two obstacles as a function of the obstacle separation distance

The separation distance (or pitch) between two successive obstacles or rows of obstacles is an important parameter in the acceleration of flame propagation and increase in explosion severity. Whilst this is generally recognised, it has received little specific attention by investigators. In this work a vented cylindrical vessel 162 mm in diameter 4.5 m long was used to study the effect of separation distance of two low blockage (30%) obstacles. The set up was demonstrated to produce overpressure through the fast flame speeds generated (i.e. in a similar mechanism to vapour cloud explosions). A worst case separation distance was found to be 1.75 m which produced close to 3 bar overpressure and a flame speed of about 500 m/s. These values were of the order of twice the overpressure and flame speed with a double obstacle separated 2.75 m (83 characteristic obstacle length scales) apart. The profile of effects with separation distance was shown to agree with the cold flow turbulence profile determined in cold flows by other researchers. However, the present results showed that the maximum effect in explosions is experienced further downstream than the position of maximum turbulence determined in the cold flow studies. It is suggested that this may be due to the convection of the turbulence profile by the propagating flame. The present results would suggest that in many previous studies of repeated obstacles the separation distance investigated might not have included the worst case set up, and therefore existing explosion protection guidelines may not be derived from worst case scenarios.     

Consequence analysis by means of characteristic curves to determine the damage to humans from the detonation of explosive substances as a function of TNT equivalence

In a previous paper, the characteristic overpressure–impulse–distance curves for the detonation of explosive substances were presented. They allow the overpressure and impulse to be determined at each distance from the detonation. When combined with damage criteria (such as those shown by the Probit equations), the characteristic curves allow consequence analysis for this kind of explosion to be carried out in only one step, as the damage is shown in the same diagram as the overpressure, impulse and distance. In this paper, diagrams and equations are presented to determine the damage to humans (eardrum rupture, death due to displacement and skull fracture, death due to displacement and whole body impact, and death due to lung damage or lung haemorrhage).     

Consequence analysis of an open fire incident in a pesticide storage plant

This paper deals with the consequence assessment of an open fire incident in a Pesticides Storage Facility. Consequences are mainly caused by the atmospheric dispersion of toxic substances produced during the fire and transported downwind to considerable distance. An integrated methodology, based on Computational fluid Dynamics (CFD) techniques and the dimensionless buoyancy flux number, F/U³L, a parameter that can be associated with the flow characteristics, taking advantage of the dynamic similarity of the flow domain, is presented and used for the simulation of the plume dispersion.Rise to the present study gave a real incident, which happened in northern Greece in the beginning of 2004 and constituted the basis for the development of the accident scenarios eventually studied. Owing to the uncertainty in the estimation of source term strength and specifically of the magnitude of the heat released during the incident together with the variation in wind velocity, a parameterization of these two quantities has been applied. Four typical accident scenarios have been designed and studied.It is concluded that the proposed methodology allows for the calculation of the ground level concentration of any non-reactive substance dispersed in the atmosphere and constitutes a complementary approach in the consequence analysis of accidents in agrochemical (pesticides) plants.