Transport Mode Selection for Toxic Gases: Rail or Road?

A significant majority of hazardous materials (hazmat) shipments are moved via the highway and railroad networks, wherein the latter mode is generally preferred for long distances. Although the characteristics of highway transportation make trucks the most dominant surface transportation mode, should it be preferred for hazmat whose accidental release can cause catastrophic consequences? We answer this question by first developing a novel and comprehensive assessment methodology—which incorporates the sequence of events leading to hazmat release from the derailed railcars and the resulting consequence—to measure rail transport risk, and second making use of the proposed assessment methodology to analyze hazmat transport risk resulting from meeting the demand for chlorine and ammonia in six distinct corridors in North America. We demonstrate that rail transport will reduce risk, irrespective of the risk measure and the transport corridor, and that every attempt must be made to use railroads to transport these shipments.     

A GIS-Based Framework for Hazardous Materials Transport Risk Assessment

This article presents a methodology for assessment of the hazardous materials transport risk in a multicommodity, multiple origin-destination setting. The proposed risk assessment methodology was integrated with a Geographical Information System (GIS), which made large-scale implementation possible. A GIS-based model of the truck shipments of dangerous goods via the highway network of Quebec and Ontario was developed. Based on the origin and destination of each shipment, the risk associated with the routes that minimize (1) the transport distance, (2) the population exposure, (3) the expected number of people to be evacuated in case of an incident, and (4) the probability of an incident during transportation was evaluated. Using these assessments, a government agency can estimate the impact of alternative policies that could alter the carriers' route choices. A related issue is the spatial distribution of transport risk, because an unfair distribution is likely to cause public concern. Thus, an analysis of transport risk equity in the provinces of Quebec and Ontario is also provided.     

A Framework for Hazardous Materials Transport Risk Assessment

In this paper, we provide a framework for quantitative risk assessment in hazardous materials transport. We first outline a basic model where population centers are approximated by points on a plane with the assumption that in the case of an incident all residents in a population center will experience the same consequences. Different versions of this model have been used by other authors in the literature. This model may be valid if the hazardous materials route goes by small population centers. Then we extend this basic model to assess risks of shipping hazardous materials through large population centers that cannot be modeled as single points on a plane. In the extended model, large population centers are treated as two-dimensional objects on the plane, which allows for a more accurate treatment of consequences than the basic model. To the extent of our knowledge the extended model is novel. We provide numerical examples for both the basic and the extended models, and finish by discussing limitations of the suggested risk assessment framework.     

Predicting the Risk of Biological Invasions Using Environmental Similarity and Transport Network Connectedness

Understanding the risk of biological invasions associated with particular transport pathways and source regions is critical for implementing effective biosecurity management. This may require both a model for physical connectedness between regions, and a measure of environmental similarity, so as to quantify the potential for a species to be transported from a given region and to survive at a destination region. We present an analysis of integrated biosecurity risk into Australia, based on flights and shipping data from each global geopolitical region, and an adaptation of the “range bagging” method to determine environmental matching between regions. Here, we describe global patterns of environmental matching and highlight those regions with many physical connections. We classify patterns of global invasion risk (high to low) into Australian states and territories. We validate our analysis by comparison with global presence data for 844 phytophagous insect pest species, and produce a list of high‐risk species not previously known to be present in Australia. We determined that, of the insect pest species used for validation, the species most likely to be present in Australia were those also present in geopolitical regions with high transport connectivity to Australia, and those regions that were geographically close, and had similar environments.     

城市路网运输性能退化成本评估模型

路网的运行受到诸多因素的影响而使得路网运输性能发生退化,分析了路网运输性能退化的影响因素和作用机理,给出了路网运输性能退化及退化的极端情况路段失效的成本分析过程框架.基于BPR路阻函数和用户均衡分配理论分析路网运输性能退化的成本函数,建立了拥堵情况下城市路网路段失效的成本评估模型.最后,通过实例分析了路网运输性能退化对出行成本影响的变化规律,给出了路网运输性能退化的极端情况路段失效成本评估的具体过程,研究表明路网运输性能退化对出行成本具有很大的影响,二者成显著的正相关关系.     

基于交通量风险的PPP交通项目再融资产品设计

交通PPP项目的投资大、风险高。政府作为发起方,需要为项目提供担保以吸引社会资本方的参与,但过度依赖政府担保意味着：一旦发生数额较大的债务违约将会给财政造成巨大的负担,因此有必要谋求适宜的市场化融资渠道。为了协调PPP项目相关者的利益,本文在项目收益债的基础上嵌入了与项目未来收益挂钩的或有条款,并运用结构化方法中的Merton模型在风险中性情景下对融资产品进行了定价。最后,以某PPP交通项目为例,进行了具体的融资产品设计,计算了相应的产品价格和风险价差,并对某些关键条款进行了敏感性分析,结果表明该产品能够在有效减轻政府担保的基础上降低融资成本。     

A Risk Evaluation of the Chlorine Industry in North America

This study analyzes the risk involved in the chlorine industry in North America. A hypothetical chlorine plant with diaphragm electrolytic cells and a chlorine production of 300,000 metric tons per year was studied. Risk in terms of man-days lost per year was evaluated for nine stages in the manufacture and distribution of chlorine. The highest risk was found to be "Maintenance of the Chlorine Plant" (37.6% of total man-days lost per year). "Raw Material Acquisition for Materials in Chlorine Plant" (1.3%) and "Storage of Chlorine at Chlorine Plant" (0.3%) both had very little risk. "Transport of Chlorine to User by Rail, Pipeline, Barge, and Truck Combined" also gave relatively low risk (10.2%), an important result since this risk is involuntary and is the category that usually causes the most concern. The kind of risk evaluation presented here, while relatively new, should be helpful in identifying those areas in industry on which time and money can be spent with maximum benefit to reduce risk.     

Perceived Risks of Radioactive Waste Transport Through Oregon: Results of a Statewide Survey

Transportation of hazardous materials, and particularly radioactive wastes, on public highways has become an important risk management issue. The unfavorability of public attitudes regarding hazardous and nuclear wastes signals the potential for strong public opposition to programs for transporting these materials. This paper presents the results of a survey conducted to assess public reactions to a long-term nuclear waste transport program planned to follow a route through a portion of rural Oregon. The survey assessed a number of key risk perception issues, including perceived health and safety risks of nuclear waste transport, relative risks of transport vs. storage at an existing site, trust in state officials, and satisfaction with life in communities along the transport route. The survey identified a number of attitudes and concerns that need to be understood and considered by those in charge of designing and implementing the waste-transportation program.     

Using GIS in Risk Analysis: A Case Study of Hazardous Waste Transport

This paper provides an illustration of how a geographic information system (GIS) can be used in risk analysis. It focuses on liquid hazardous waste transport and utilizes records archived by the London Waste Regulatory Authority. This data source provides information on the origin and destination of each waste stream, but not the route followed during transport. A GIS was therefore employed to predict the paths used, taking into account different routing criteria and characteristics of the available road network. Details were also assembled on population distribution and ground-water vulnerability, thus providing a basis for evaluating the potential consequences of a waste spillage during transport. Four routing scenarios were implemented to identify sections of road which consistently saw heavy traffic. These simulations also highlighted that some interventions could lead to risk tradeoffs rather than hazard mitigation. Many parts of the research would not have been possible without a GIS, and the study demonstrates the considerable potential of such software in environmental risk assessment and management.     

双层规划在城市交通污染控制中的一个应用

本文从控制城市交通污染的角度出发,考虑到用户的路径选择行为,采用双层规划模型描述城市交通管理与污染控制问题,并给出了相应的启发式求解算法及算例,在此基础上,提出了城市交通管理与污染控制框架。     

Urban Risks of Truck Transport of Radioactive Material

Truck transport of radioactive material (RAM), e.g., spent nuclear fuel (SNF), normally maximizes use of Interstate highways, which are safer and more efficient for truck transport in general. In the estimation of transportation risks, population bordering a route is a direct factor in determining consequences and an indirect factor in determining exposure times, accident probabilities and severities, and other parameters. Proposals to transport RAM may draw intense resistance from "stakeholders" based on concern for population concentrations along urban segments but the length of a route segment is also a determinative factor in estimating the transport risks. To quantify the relative importance of these two factors, a potential route for transport of SNF (strict use of Interstate highways) was selected and compared with a modified version that bypassed urban areas. The results suggest that emphasis on Interstate highways minimizes total route and urban segment risks.     

An Integrated Approach for Assessing the Impact of Large-Scale Future Floods on a Highway Transport System

The negative impact of climate change continues to escalate flood risk. Floods directly and indirectly damage highway systems and disturb the socioeconomic order. In this study, we propose an integrated approach to quantitatively assess how floods impact the functioning of a highway system. The approach has three parts: (1) a multi-agent simulation model to represent traffic, heterogeneous user demand, and route choice in a highway network; (2) a flood simulator using future runoff scenarios generated from five global climate models, three representative concentration pathways (RCPs), and the CaMa-Flood model; and (3) an impact analyzer, which superimposes the simulated floods on the highway traffic simulation system, and quantifies the flood impact on a highway system based on car following model. This approach is illustrated with a case study of the Chinese highway network. The results show that (i) for different global climate models, the associated flood damage to a highway system is not linearly correlated with the forcing levels of RCPs, or with future years; (ii) floods in different years have variable impacts on regional connectivity; and (iii) extreme flood impacts can cause huge damages in highway networks; that is, in 2030, the estimated 84.5% of routes between provinces cannot be completed when the highway system is disturbed by a future major flood. These results have critical implications for transport sector policies and can be used to guide highway design and infrastructure protection. The approach can be extended to analyze other networks with spatial vulnerability, and it is an effective quantitative tool for reducing systemic disaster risk.     

基于合作性投资和价格策略的多式联运企业协作行为博弈分析

本文对联合运输中不同运输企业间的协作行为进行了研究。考虑了两家提供互补运输服务的寡头运输企业之间的合作和竞争的博弈决策问题,通过定义合作强度参数,并将其引入收益函数,构造了合作性投资和价格策略的两阶段动态博弈模型,讨论了该博弈子博弈完美Nash均衡解的存在条件,推出了一些重要的结论。研究发现:当双方投资效果系数组合在(0,1)区间时,随着市场潜量的增加,投资增长;随着价格弹性的增加,投资下降。而当双方投资效果系数组合在(1,2)区间时结论相反。最后通过算例和所设计的免疫遗传算法进行了不同参数环境下的数值模拟,验证了结论的正确性。     

基于平均最小间隔的城际铁路线路运输能力计算模型

在城市群交通一体化迅速发展的大背景下,本文针对城际铁路的运输能力计算问题提出一种与之相适应的计算模型。首先,文章在分析城际铁路运营特点基础上,基于整数线性规划建立计算模型,该模型利用平均最小间隔时间法中将两列相邻的列车组合为运行列车组作为运行图结构单元的思想来计算列车占用运行图总时间,并以最大化运行列车组总数为目标函数,以规定列车占用运行图总时间的有效时间范围为约束条件。最后,文章通过京津城际实际数据算例,验证了文章所提计算模型相较于传统计算方法更切合城际铁路运营实际。该模型大幅简化了城际铁路线路运输能力的计算步骤,提高了计算效率,能够助力于改善城际铁路运输能力及其运营服务水平。     

我国综合客运需求函数及各种客运方式的需求格局

分析了我国客运需求的主要影响因素,提出基本需求和活动需求概念,研究了我国客运需求函数的一般表达式和实证形式。认为各客运方式的需求应依赖于其竞争的状态,各客运方式将主要集中在典型竞争因素上开展竞争,其各自的市场需求份额将趋于一个较合理的比例。用AHP定量方法并结合定性方法推算出了这一比例。     

Accidents and Unpleasant Incidents: Worry in Transport and Prediction of Travel Behavior

Worry on nine different means of transport was measured in a Norwegian sample of 853 respondents. The main aim of the study was to investigate differences in worry about accidents and worry about unpleasant incidents, and how these two sorts of worry relate to various means of transport as well as transport behavior. Factor analyses of worry about accidents suggested a division between rail transport, road transport, and nonmotorized transport, whereas analyses of worry about unpleasant incidents suggested a division between transport modes where you interact with other people and "private" transport modes. Moreover, mean ratings of worry showed that respondents worried more about accidents than unpleasant incidents on private transport modes, and more about unpleasant incidents than accidents on public transport modes. Support for the distinction between worry about accidents and unpleasant incidents was also found when investigating relationships between both types of worry and behavioral adaptations: worry about accidents was more important than worry about unpleasant incidents in relation to behavioral adaptations on private means of transport, whereas the opposite was true for public means of transport. Finally, predictors of worry were investigated. The models of worry about accidents and worry about unpleasant incidents differed as to what predictors turned out significant. Knowledge about peoples' worries on different means of transport is important with regard to understanding and influencing transport and travel behavior, as well as attending to commuters' welfare.     

客运交通需求分析

文章针对客运交通的特点,分析了客运交通需求的几个主要影响因素,提出稳定需求和活动需求概念,并探讨了这两种需求的需求特征、时间函数、增长特征及其最优定价规律。在此基础上探讨了客运交通系统需求函数的一般表达式并给出了近年来我国客运交通系统需求函数的实证形式。     

A Bayesian Network Estimation of the Service‐Profit Chain for Transport Service Satisfaction

Bayesian network methodology is used to model key linkages of the service‐profit chain within the context of transportation service satisfaction. Bayesian networks offer some advantages for implementing managerially focused models over other statistical techniques designed primarily for evaluating theoretical models. These advantages are (1) providing a causal explanation using observable variables within a single multivariate model, (2) analysis of nonlinear relationships contained in ordinal measurements, (3) accommodation of branching patterns that occur in data collection, and (4) the ability to conduct probabilistic inference for prediction and diagnostics with an output metric that can be understood by managers and academics. Sample data from 1,101 recent transport service customers are utilized to select and validate a Bayesian network and conduct probabilistic inference.     

Quantitative Risk Analysis on the Transport of Dangerous Goods Through a Bi‐Directional Road Tunnel

A quantitative risk analysis (QRA) regarding dangerous goods vehicles (DGVs) running through road tunnels was set up. Peak hourly traffic volumes (VHP), percentage of heavy goods vehicles (HGVs), and failure of the emergency ventilation system were investigated in order to assess their impact on the risk level. The risk associated with an alternative route running completely in the open air and passing through a highly populated urban area was also evaluated. The results in terms of social risk, as F/N curves, show an increased risk level with an increase the VHP, the percentage of HGVs, and a failure of the emergency ventilation system. The risk curves of the tunnel investigated were found to lie both above and below those of the alternative route running in the open air depending on the type of dangerous goods transported. In particular, risk was found to be greater in the tunnel for two fire scenarios (no explosion). In contrast, the risk level for the exposed population was found to be greater for the alternative route in three possible accident scenarios associated with explosions and toxic releases. Therefore, one should be wary before stating that for the transport of dangerous products an itinerary running completely in the open air might be used if the latter passes through a populated area. The QRA may help decisionmakers both to implement additional safety measures and to understand whether to allow, forbid, or limit circulation of DGVs.     

多元化集成模式下交通基础设施建设融资风险识别研究

从单一模式向多元化集成模式转变已成为新形势下拓宽交通基础设施建设融资渠道的必然选择,在规避单一模式局限、形成多元模式优势合力的同时,也加剧了融资不确定性和复杂性,从而对融资风险识别提出了更高的要求。综合考虑多元化集成模式下交通基础设施建设融资风险的多源性、关联性、模糊性、随机性等典型表征,设计了与典型表征相匹配的融资风险识别框架,并构建了融资风险识别两阶段模型。在该模型中,明确了融资风险因素确定流程和维度划分规则,并提出了基于随机二元语义DEMATEL的风险因素关联分析方法进行融资风险因素的研判与诊断。最后,以“PPP+ABS”模式下大成西黄河大桥收益权计划为例开展了计算实验,验证了所构建模型的有效性,并给出了融资风险应对与化解的启示与建议。研究成果能够为相关利益主体明晰融资风险因素构成、研判融资风险因素影响力、诊断融资风险因素可控性、有效应对与化解融资风险提供系统性解决方案。