A bi-objective model for planning and managing rail-truck intermodal transportation of hazardous materials

We propose a bi-objective optimization framework for routing rail-truck intermodal shipments with hazardous materials, when shippers and receivers have access to alternate intermodal terminals. A tabu-search based solution methodology is developed, which together with the optimization framework is applied to realistic size problem instances to gain managerial insights. Our analysis indicates that drayage accounts for a significant portion of transport risk and that it can be reduced by scheduling direct and faster trains; and, that the mix of intermodal trains depends on the interest of the decision-makers, where the resulting traffic can facilitate planning emergency response systems.     

可能速度在交通安全评价中的应用

借助可能速度这一能够直观反映道路线形状况的指标,建立基于可能速度突变量的路段交通事故预测模型,预测得到的事故率可以作为安全系数,依照文中初定的评价标准,可评价突变处对应桩号位置的交通安全状况。     

区域运输结构的自组织演化机制研究——基于logistic模型的分析

运输结构是指各种运输方式在运输过程形成的功能构成和资源配置。本文尝试运用自组织理论的原理和方法,探讨了区域综合运输体系结构变化的影响因素和自组织机制,应用涌现原理、反馈原理、涨落原理和环境选择原理分析运输系统结构演化的过程,建立了运输结构自组织演化的Logistic模型,并结合湖北省沿江经济带的案例,对区域货物运输结构演化的过程和趋势以及各种运输方式之间的相互影响关系进行了分析,同时提出了自组织理论对区域运输体系建设发展的启示。     

Estimating visitors’ travel mode choices along the Bear Lake Road in Rocky Mountain National Park

The National Park Service (NPS) in the United States of America (USA) is looking to alternative transportation systems to provide visitors access to the national parks in a manner that potentially reduces traffic congestion, enhances visitors’ experiences, and more effectively protects park resources. However, shuttle bus systems without adequate planning and management may lead to unintended consequences such as eliminating the constraint to visitor use levels associated with parking lot capacities. As a consequence, the demand for recreation use in the area increases the potential impacts to the visitor experience and park resources. This study examined the trade-offs Rocky Mountain National Park visitors were willing to make about transportation mode choice using a stated choice survey to inform park managers about visitor acceptance of potential transportation related management actions. Results indicate that visitors prefer to use their private vehicles over the parks transit system but are willing to make trade-offs to ride the shuttle bus in order to avoid crowding along the trail at Bear Lake and vehicle traffic along the Bear Lake Road. In addition, there were statistically significant differences among choices of transportation mode trade-offs among different age groups (i.e., less than 40 years of age, 40–60 years of age, and more than 60 years of age) Specifically, results suggest that visitors less than 40 years are more willing than the older age groups to make trade-offs among transportation options to enhance their chances of being on the trail system at Bear Lake with fewer other people. The significant and interacted relationships with shuttle bus use, visitor use, and vehicle traffic levels found in this study provide RMNP managers opportunities to influence visitors’ transportation mode choices.     

从"畅通工程"看我国城市建设和交通管理等部门的合作协调机制

近10年来,以北京、上海、广州等为典型代表的中国城市所出现的交通问题是空前严重的.所以, 国家在2000年提出了"畅通工程"作为一个重要对策.目前,"畅通工程"已实施1年多,它给人们以什么启示?在此基础上,今后我国城市建设和交通管理等部门的合作协调又该如何进行?对此,作者进行了探讨.     

杭州的低碳城市交通实践与发展对策

在论述杭州迫切需要发展低碳交通后,对杭州实施低碳城市交通的基础与实践进行了分析,并提出了进一步实施城市低碳交通的建议.     

国内交通基础设施与出口国内增加值率——对构建“双循环”新发展格局的启示

出口增加值的国内份额能够良好地反映企业参与国内国际双循环的状况.基于2000—2013年中国微观企业数据,本文研究了交通基础设施对企业出口国内增加值率的影响与机制.研究发现,国内交通基础设施改善会对企业出口国内增加值率产生双向效应:一方面会提高企业成本加成率与国内中间品投入,进而提高企业出口国内增加值率,促进企业参与国内大循环;另一方面则会增加企业从事加工贸易的比重与进口中间品投入,进而降低企业出口国内增加值率,推动企业嵌入国际大循环.交通基础设施对企业出口国内增加值率的总体影响则取决于以上两个效应的相对大小.实证结果显示,负向效应大于正向效应,交通基础设施对企业出口国内增加值率的总体影响显著为负,且企业异质性特征显著.本文从微观层面上解释了我国"内外循环"联动发展的经济事实,为构建"双循环"新发展格局提供了有益的启示.     

IS POOLING LEAD‐TIME RISK BY SPLITTING ORDERS SIMULTANEOUSLY WORTHWHILE?

A large body of research is based on the proposition that pooling lead‐time risk by splitting orders simultaneously can offer significant opportunities to reduce inventory system costs. This paper investigates that proposition for a broad range of industry conditions, as well as for a high‐tech company in a global setting. The investigation considers important cost elements not included in previous work to conduct a realistic assessment of the value proposition. The results indicate that, even under favorable conditions, the proposition is worthwhile only when lead‐time variability and unit values are unusually high. Managerial implications and new research directions are discussed in light of these findings.     

Optimisation of the exploitation period of individual vehicles in freight transportation companies

The individual vehicle replacement problem typical for freight transportation companies is discussed in the paper. Two characteristic features of such problem are that transportation companies utilise vehicles with intensity decreasing with an age of vehicles and that managers of such companies first of all take into account economical criteria when planning vehicle replacements. The paper presents a single criterion, nonlinear, deterministic and discrete mathematical model of such a problem that minimises a total exploitation and ownership costs calculated per kilometre. The exact solution procedure is proposed here. The problem is solved as a real life case study. As a result, an average, economically optimal 5-year exploitation period of vehicles has been determined.