大规模多式联运复杂网络系统模型

与其他优化问题相比,多式联运网络路径优化问题面临着变量较多且其结构、关系复杂的困扰．然而,现有的多式联运网络只能对网络属性逐一计算,难免重复冗余,效率偏低,只适用于小型网络．提出了不规则棱柱网络模型．采用相对编码设计,通过搜索判断余子式进行网络初始化,将网络中不同类别的弧线解释成满足某种约束条件的量,通过设计底边判断函数和侧棱判断函数,实现了网络中弧线的智能分类．该模型取消了运输网络阶段划分的限制;其节点与现实运输的地理坐标相对应;分类判断可以对网络进行群体修建与更新．通过对比各网络的时间频度,说明在多属性变量复杂且多样性的大规模多式联运网络中,该网络能够极大地提升网络构建和更新效率．     

三体高速客货运输船设计方案概要

多体船与同吨位单体船相比,前者可获得单位面积排水量时更大的甲板面积、良好的横稳性、优良的抗沉性和适航性。高速水运相对于其他运输方式而言,具有装载量大、营运成本低、初始投资少等显著优势。文中以某型具有特定滚装功能(可携带冷藏集装箱、汽车等)的三体客货运输船为例,详细介绍其主要技术参数、设计方案、材料和动力装置的选取情况,总结了三体船的受力特点,对同类型船设计中危险工况确定的强度分析和结构优化具有一定的指导意义。     

施工产生的悬浮泥沙对附近海域水质影响的定量预测分析

为了全面地了解珠海港LNG航道附近海域的潮流分布特征,在查阅有关该海域及其附近海域水文特征的基础上,结合模拟区附近的测流站、验潮站资料以及有关前期工作资料,采用数值模拟方法对工程海区及其附近海域的潮流场状况进行了数值模拟计算,再现了模拟区的潮流运动过程和特征。在海域潮流场进行模拟计算的基础上,对挖泥施工过程产生的悬浮物的扩散浓度场进行预测,以此来分析建设施工期间对附近海域水质的影响。     

Calculation of external costs for freight transport

Abstract

The negative impacts of transport are in general associated with costs. These costs are usually denoted as ‘external costs’ or ‘externalities’. This paper presents a tool for calculating external costs for freight transport together with its application to a number of case studies. The categories considered include: air pollution, greenhouse gases, noise, accidents and congestion. Results are presented for a number of different transport alternatives as total costs and divided into categories. The uncertainties in the results are discussed. The assessment of these costs is essential for predicting future transport costs.     

New operating concepts for intermodal transport: The mega hub in Hanover/Lehrte in Germany

In intermodal logistics, combined transport operators and railway companies are engaged in the development of efficient block train concepts. The proportion of transport using single railway wagons is decreasing because of its poor time-quality ratio. In future, transport services will be focussed on industrial zones and large cities that offer the transport volumes required for direct train operation. In this regard, it will become more difficult for regions with smaller load volumes to be integrated into a combined transport network. In order to confront this trend, new concepts for bundling transport volumes have to be developed. One such concept is the 'mega hub'. The core idea is to interchange load units between several block trains during a short stop at an intermodal terminal. The paper provides an overview of the operating concept of the mega hub and the opportunities for intermodal transport operators.     

Evaluation of the Transferability of Incident Detection Algorithms Developed for Singapore Expressways

ABSTRACT

Two new detection algorithms, single-station DV (dual-variable) and dual-station CODE (COmbined Detector Evaluation) were developed earlier using 160 incidents collected along Singapore's Central Expressway (CTE). The transferability of these CTE-developed algorithms is assessed, as a case study, using 100 incidents collected from the Tullamarine Freeway and South Eastern Freeway in Melbourne, Australia. The investigation covers the differences in traffic detector systems (loop detectors versus video-based), road geometry and behaviour between drivers in Singapore and Australia. The re-calibrated application of these algorithms to freeways in Melbourne yielded a reasonably good detection performance as well as satisfying the average expected performances of seven traffic management centres surveyed in the USA. The results suggested that the detection logic of the algorithms developed for CTE possessed reasonably good transferability and are also suitable for receiving traffic inputs from video-based detectors as well as from loop detectors.     

A Stated Preference Experiment for Measuring Service Quality in Public Transport

Abstract

This paper develops a Stated Preference (SP) experiment that provides a way to measure service quality in public transport. The paper introduces an empirical procedure for optimising the SP experiment. This procedure permits the identification of the choice alternatives defining the experiment by simulating the choices of a user sample. By using the data collected from an experimental survey, a Multinomial Logit model was calibrated. This model is a way of identifying the importance of service quality attributes on global customer satisfaction and calculating a Service Quality Index, which provides an operationally appealing measure of current or potential service effectiveness.     

Modelling greenhouse gas emissions from cars in Great Britain

This paper outlines the issues involved in the problem of global warming. The road transport sector's contributions to this problem are then detailed and various policy options to reduce greenhouse gas emissions from private cars are discussed. The paper then describes a model which forecasts greenhouse gas emissions from cars. The effects of various policy options are then modelled and the results compared. Policies considered include: raising fuel prices in terms of the UK government's commitment to increase road fuel duties; subsidising public transport in terms of reduced public transport fares; and a tax differentiated by engine size.     

Monopoly,Subsidies and the Mohring Effect: A Synthesis

Abstract

This paper provides a unifying framework to analyze whether a monopoly transit provider will under or over-supply frequency. To this end we couch the problem in term of Spence [(1975). Monopoly, quality and regulation. The Bell Journal of Economics, 6, 417–429] who analyzed the incentives to provide quality by a monopolist. We show that all of the results of a recent academic exchange discussing this topic are special cases of Spence [(1975). Monopoly, quality and regulation. The Bell Journal of Economics, 6, 417–429], albeit with an adjustment in order to take into account the cost structure of frequency provision in the case of public transport. In theory then, there are cases when a monopolist may offer optimal or above optimal levels of frequency without requiring subsidies. However, public transport is rarely provided by an unregulated monopolist. Rather, these services are usually provided either by an exclusive operator under regulated fares or by a group of competing operators, with or without fare regulation. We show that in the first case frequency will always be below the social optimal level.     

Approaches and Techniques for Modelling CO2 Emissions from Road Transport

Abstract

Transport accounts for around a quarter of CO₂ emissions globally. Transport modelling provides a useful means to explore the dynamics, scale and magnitude of transport-related emissions. This paper explores the modelling tools available for analysing the emissions of CO₂ from transport. Covering a range of techniques from transport microsimulation to global techno-economic models, this review provides insights into the various advantages and shortcomings of these tools. The paper also examines the value of having a broad range of perspectives for analysing emissions from transport. The paper concludes by suggesting that the broad range of models creates a rich environment for exploring a spectrum of policy questions around the emissions from transport, and the potential for combining modelling approaches further enhances the understanding that can be attained.