Platooning for sustainable freight transportation: an adoptable practice in the near future?

ABSTRACT

Platooning is an emerging transportation practice that has the potential to solve the problems of the burgeoning transportation industry. A platoon is a group of vehicles, with vehicle to vehicle communication, that travel closely behind one another such that the platoon can accelerate, brake and cruise together. Platoons can improve road safety, be energy efficient and reduce costs. Its complete socio-economic benefits include congestion mitigation, smoother traffic flow, better lane usage and throughput, incentives for green logistics and driver safety. The long-term effect of platooning on road transportation, if extensively deployed, would be better organised traffic flow and efficient tracking of vehicles on the road ushering a multilevel positive impact on the industry. In this study, we attempt to answer the critical question of whether platooning is an adoptable practice in the near future and discuss an agenda to take platooning closer to implementation on the ground by highlighting the opportunities for future research. We also present a conceptual framework to help researchers, academicians, policy makers and practitioners for the adoption of platooning into the transportation industry.     

Deregulating the bus industry in Britain: a reply

In the last four years, some 20 urban areas in the UK have commissioned or considered conducting Integrated Transport Studies, which are designed to develop a transport strategy for the next 20–30 years. Such studies represent a new approach to transport policy formulation, since they respond to a vision of the future for the area, treat a wide range of transport and land use policy instruments, emphasize synergy between those instruments, and provide a framework for facilitating action rather than a rigid blueprint for the future. They also differ from past studies in the speed with which they have been conducted, and in the analytical techniques which have made this possible. This paper reviews the background to these studies, the evaluation approach adopted, the policy instruments considered and the analytical methods developed for the studies. It concludes with an assessment of the policy implications stressing in particular the need to reduce trip length, the crucial impact of pricing as an instrument of transport policy, the importance of achieving synergy in strategy development, and the requirement for a common basis for evaluating and financing different transport policy instruments.     

Testing port choice models using physical and monetary data: a comparative case study for the Spanish container trades

ABSTRACT

Transport costs are useful explanatory variables in port choice research. Nevertheless, the availability of such information usually poses a problem. Thus, the formulation of an alternative approach, to be used as a proxy of these variables, would be desirable. The objective of this study is to improve the analysis of container port choice using logit models by adopting physical non-monetary indicators based on maritime distance and ship size. The statistical tests of logit models on port choice using these new variables are compared with the result of using cost variables for the same data set of choice positions. The statistical outcome is good and allows us to present this new approach as a contribution to the literature on port choice modeling.     

Visual landscape classification in the coastal strip of Santander (Spain)

Abstract

The coastal landscape in Santander, Spain, is analyzed in terms of landscape quality and fragility (or vulnerability). Quality is intended to indicate those areas of major landscape value for conservation purposes. Fragility is utilized to detect areas which could easily deteriorate if certain human activities are carried out. The authors’ study has three clearly differentiated phases. In the first, landscape units are defined and mapped. In the second, units are classified by computerized techniques and grouped according to significance. In the third phase, the true significance of the groups is interpreted. A mountainous, coastal zone in northern Spain was chosen for this study. Landscape units were determined by visual criteria with strong topographical bias. The area covered by each unit is that visible to an observer situated approximately in its center. Each unit is represented by certain biophysical and visual variables. Data were subjected to clustering analysis on the basis of using three ad casum defined “distances.”; The first distance gives unit classifications grouped according to similarity or proximity of their characteristic variables. In this case, inventory data only are used, no subjective value judgments were introduced in the process. Value judgments are made at the end on the resulting groupings of units. Two other distance classifications are determined by the similarity or proximity of the units making up each group according to the landscape quality and fragility values of each unit. In these latter cases, classification is influenced by value judgments introduced at the beginning of the process. These procedures are more subjective but give more congruent results. With each mathematical distance configuration, an analysis is made of the variables shown to be most representative and which have, therefore, shown greatest discriminatory power in selecting final groups. Finally, the different possibilities of the above techniques are discussed as well as their potential generalization to other fields demanding the treatment of qualitative landscape variables.     

Second international conference on new survey methods in transport Hungerford Hill,Australia 12–16 September 1983

The Second International Conference on New Survey Methods in Transport was held at Hungerford Hill, Australia in September 1983. The aims of the conference were to provide a focus for discussion of survey methodology and to establish bench‐marks with respect to the state of the art in various facets of transport surveys. The conference evolved around workshops in twelve key areas: sample design, survey needs for modelling, questionnaire design and piloting, perceptual studies, diary surveys, longitudinal studies, interactive survey methods, freight surveys, traffic surveys, total design concepts, response errors and data correction, and coding and computing.

A number of plenary keynote papers were also presented describing the state of the art in cross‐sectional, longitudinal and interactive survey methods. Emerging from the conference discussions, six key issues were prominent; the gap between the state of the art, as espoused by researchers, and the state of practice, as employed by practioners; the differences in results obtained when employing different survey methods to collect essentially the same data; the emerging use of the telephone for the conduct of interview travel surveys; the interaction between survey methods and demand modelling and the disparate levels of sophistication in the two areas; the role of microcomputers in the design, conduct and analysis of transport surveys; and the need for practitioners to engage in controlled experimentation, so that methodological advances may continue to be made in the field of transport surveys.     

Nigerian railways: problems and prospects

The very special topography of Greece with the hundreds of mainland and island ports generates vast possibilities for developing routing networks to link the ports to each other while satisfying total demand. An algorithm which minimizes total operating costs (fixed and variable) has been adapted and used to determine an optimal network solution. The total operating costs of this solution is compared to the total operating costs of the existing (1964 data) network and the optimal networks when fixed and variable costs are minimized independently. It is found that the actual network follows the minimal total operating costs solution quite closely.     

Sea space capacity and operation strategy analysis system

Sea space planning and congestion management is receiving more attention. However, little work on sea space capacity and strategy analyses can be found in the literature. Compared to other transportation systems, a sea space system has some special features that require consideration. The system capacity also depends on the pattern of traffic using the system. In this paper, we model a sea space as a directional network and capacity models for berthing areas, anchorage areas, fairways and their intersections, as well as the entire sea space system are developed. These models can be used to compute capacity for any given traffic pattern which can be extracted from vessel trip records or from traffic forecasts. To implement these models, a software system called Sea Space Capacity and Strategy Analysis System (SCSAS) has been developed in Visual C + + and is now being used in Singapore.     

Structure,conduct and performance on the major liner shipping routes 1

Market concentration on the major container shipping routes has the potential to reduce contestability, impede effective competition and, as a consequence, inhibit the positive relationship between trade and economic growth. This development could also hamper the ability of economic regions to realize their respective competitive and comparative advantages. Within this context, the structure-conduct-performance (SCP) framework is used to analyse liner shipping dynamics in the transpacific, Europe–Far East and transatlantic trade routes. The analysis finds no conclusive evidence that either the increased concentration of slot capacity or the attempts by shipping lines to boost potential slot capacity (mainly through collaborative arrangements) lead to improved financial performance. The paper concludes that, despite high and increasing concentration among carriers on each of the trade routes analysed, these markets remain contestable.     

软弱地层浅埋大跨隧道跳仓法拆撑空间效应研究北大核心CSCD

对于在软弱、破碎、富水地层中采用双侧壁导坑法修筑的暗挖大跨隧道,跳仓法施工依赖于初期支护的“棚护效应”维持拆撑后大跨结构的稳定性,常常面临拆撑步距小、风险高、效率低、代价大的困境,一旦拆撑方案采取不当,极易造成塌方安全事故。针对这一问题,以青岛地铁4号线错埠岭站为依托工程,通过理论分析与数值计算相结合的手段,论证了拆撑后初期支护“空间棚护效应”主要由“横向成拱效应”和“纵向成梁效应”组成,二者共同维持大跨结构的安全性与稳定性;同时确定了合理、安全、高效、快速的拆撑分区长度与隔仓分区长度,分别为L=9 m、S=18 m,并顺利通过了现场施工的检验。结果表明:软弱地层大跨隧道采用“隔二拆一、先内部后洞口”的拆撑方案是切实可行的,可为后续工程提供借鉴与指导。     

Research developments in numerical methods of fluid-structure interactions in naval architecture and ocean engineering北大核心CSCD

流固耦合问题较为复杂,通常难以通过理论推导求得,而数值模拟则能提供一种有效的解决方案,并被广泛用于船舶与海洋工程领域。流固耦合数值方法根据其网格离散方式,可以分为贴体网格方法、非贴体网格方法、重叠网格方法和粒子类方法 4类,对这4类方法的特点及研究进展进行概述并总结得出:贴体网格方法和重叠网格方法均能精确捕捉界面的变形和演化,适合高雷诺数流动问题,在考虑结构变形时一般采用贴体网格方法,而考虑复杂几何形状的刚体运动时则常采用重叠网格方法;非贴体网格方法能够避免网格的更新操作,使计算较为简单,目前多用于模拟流动控制、水下柔性仿生航行器的研发以及多体运动干扰等问题;粒子类方法因其固有的拉格朗日属性,在模拟涉及自由液面剧烈变形、砰击、爆炸等强非线性流固耦合问题中发挥着重要作用。不同的流固耦合问题属性决定了不同方法的适用性,如何选取适合的数值方法,同时结合各类方法的优势开发新的计算方法以应对更为复杂的问题,是流固耦合算法开发的重要发展方向。