钢纤维喷混凝土应用之我见

软弱围岩隧道中的初期支护采用网喷混凝土已成定式.文章在论述钢纤维喷混凝土的作用机理、设计计算方法、耐久性以及与网喷混凝土经济比较的基础上,提出了全新的隧道初期支护的设计思路.     

Comments on flow characteristics on acceleration lanes

This paper deals with driver behavior while travelling on and merging from acceleration lanes. Two possible groups of drivers were identified: drivers who always perform the merging maneuver during the second part of the acceleration lane, regardless of whether an appropriate gap or lag was available to them previously. Three components of the aggregated delay for the merging process were suggested and evaluated. A method of estimating the random delay and travel time on acceleration lane was proposed and evaluated against an aggregated empirical data obtained on three freeway acceleration lanes. An evaluation of the contribution of the ramp volume to the traffic delay was also performed and discussed and a graph which may be of practical use for road and traffic engineers in assessing the expected influence of various ramp and freeway volume combinations is presented.     

关于盾构隧道楔形管片环的思考

文章从理论分析和工程实践的角度探讨盾构隧道楔形管片环的技术特点并总结相关规律,包括线路拟合、楔形方式和楔形量等,可供同行在设计与施工中借鉴或参考.     

对公路隧道施工监测的几点探讨

结合工程实例介绍了公路隧道施工监测的主要内容及其作用,并对施工监测中存在的一些问题进行了探讨,对提高公路隧道施工监控量测的质量具有一定的指导作用。     

隧道弃碴弃置处理应注意的几个问题

文章结合我国有关铁路隧道群地段隧道弃碴弃置情况的经验总结,指出了当前对隧道弃碴弃置处理应该重视的几个问题,并提出了有关建议.     

公路隧道围岩分级中存在问题的探讨

采用了国标的围岩分级方法进行隧道围岩分级.新规范实施后,很多建设业主反应采用新规范的隧道围岩分级普遍偏高,致使工程造价普遍增加.文章对围岩分级和原围岩分类进行了比较,对围岩分级的定性与定量数据进行了对比分析,阐明了出现这一现象的原因,提出了准确使用新规范围岩分级方法的几点建议.     

公路隧道施工地质工作的几点看法

文章简要地阐述了对公路隧道施工地质工作的几个问题的看法,包括隧道施工地质工作的现状、施工地质步骤与地质工作方法、超前地质预测的综合分析思路与方法,以及地质人员素质和地质知识技能的提高。     

浅埋暗挖法设计理论论述

王梦恕院士在多年工程实践和理论研究的基础上,著成我国第一部全面系统论述"浅埋暗挖法"理论、设计、施工的专著--<地下工程浅埋暗挖技术通论>,对浅埋暗挖技术的理论基础、工程理念、设计与施工方法进行了全面论述.浅埋暗挖设计理论其创新点可以概括为隧道埋深的界定及荷载计算、隧道断面型式确定、邻近地下工程及其穿越方式、断面衬砌设计、结构防水设计、结构设计计算、预支护设计及网构钢拱架设计,并提出了浅埋暗挖法理论设计原则,形成了一套完整的浅埋、超浅埋隧道与地下工程设计、施工理论体系.     

Effects of subsidies on urban public transport

Because of a general trend of increasing costs of public transport operations and higher subsidies (in some cases accompanied by falling patronage) the European Conference of Ministers of Transport (ECMT) initiated a study of subsidisation and sought the help of the Transport and Road Research Laboratory. The study, in which eighteen countries took part, was concerned with the aims of subsidy, the sources and conditions attached to subsidy, trends in subsidies and the effect of subsidies on patronage, fares, service levels, costs and productivity.The qualitative information concerning the aims of subsidy was analysed in relation to the likelihood of achieving such aims, taking into account current experience of attempts to switch car drivers to public transport. The quantitative information on trends referred to public transport stage services covering where possible the entire country and relating to the period 1965–77; these data were supplemented by data from 59 cities in different parts of the world collected in the course of a TRRL-sponsored study of travel demand factors. The relationship between patronage and service levels, and between subsidies and various operating factors, including costs and productivity, were studied using regression analysis and the general conclusion reached was that although the major part of the subsidy paid was reflected by reduced fares and improved service levels there may well have been some leakage into higher unit costs and manning levels.     

对青岛胶州湾隧道超前地质预报工作的思考及建议

超前地质预报工作应当编制相应的地质预报方案,海底隧道尤应如此.地质预报方案编制前,必须充分掌握熟悉隧道施工场区的地质背景条件,不同的地质背景,地质条件不同、地质复杂程度不同、勘察难度不同,因此有不同的地质预报方案.文章阐述了隧道超前地质预报工作的目的、性质以及编制超前地质预报方案的指导思想,着重强调地质观察研究在地质预报工作中的重要性.通过对超前预报相关合同文件所规定的预报手段的效用及特点的阐述以及人们对地质背景条件的不同认识,提出了胶州湾隧道不同的地质预报方案,同时对地质预报工作提出了建议.     

Reflections on Travel Time Savings: Comments to David Metz

Shipping companies frequently outsource the management of their vessels. In this paper, we use data from Lloyd's Register Fairplay [(2009) IHS Fairplay World shipping encyclopaedia. Available at http://www.ihs.com/products/maritime-information/ships/world-shipping-encyclopedia.aspx?pu=1&;rd=ihsfairplay_com] on 45 456 vessels belonging to 9580 different ship-owners to investigate the extent of outsourcing in shipping and to identify the key factors affecting the likelihood of outsourcing. The results of our econometric analysis indicate that ship-owners' decisions to outsource are explained by the characteristics of the vessels in question (age, type and size) and the characteristics of the ship-owner (country of domiciliation and number of vessels). In addition, a specific country effect is identified for Greek ship-owners, which is in line with the findings of previous studies.     

Reflections on transport in the future

Abstract

The first INTRA Seminar, held at the College of Europe, Bruges, in April 1982, was on the theme Transport in the Future: some possibilities and their implications. This theme was chosen to give an opportunity to consider transport requirements and resources in the broadest possible way, and as a prelude to later Seminars on more specific subjects. Throughout, the emphasis was on major trends and possible discontinuities which may have important policy consequences. The seminar also aimed to help participants—who attended by personal invitation—to broaden and deepen their understanding of the role and nature of transport and its internal and external relationships.

These ‘reflections’ are intended for wider circulation, particularly for senior officials in national and international organizations not directly or regularly involved in transport but who may find it helpful in their own activities. They are not intended to be either complete or comprehensive, but deliberately emphasize those aspects which participants identified as requiring more consideration and examination. The opening section, entitled Overall Impressions, is a brief general statement. The fuller account of the Seminar which follows is largely based on the Working Paper circulated before the Seminar, on introductory Statements on particular topics prepared by participants, and on the reports by the Moderators of Study Groups; it has also benefited from advice and suggestions from others who intended to take part but who were prevented from doing so.

Since this account has been prepared by the two INTRA organizers, it naturally reflects their views of these papers, discussions and suggestions. Equally, any views expressed are not necessarily those of all participants—or, indeed, of any individual participant—nor of the organizations or institutions with which they are associated.     

2006春运评弹

2006春运特点 胡佛如:在座有来自运管部门的领导,有客运站和客运企业的经理,还有专家,相信您们对春运都感受颇深,所以,本期沙龙,我们以"2006年春运的特点"作为开篇话题,请大家谈谈感受……     

Feasible provision of targeted traveler information in public transportation: Segmentation based on functional limitations

This paper presents findings on the need for traveler information among people with functional limitation(s), and how the need varies between groups with different functional limitation(s). Chi-Squared Automatic Identification Detector (CHAID) was used to identify groups (segments) in order to understand how functional limitations contribute to the need for traveler information. The key findings suggest that people with functional limitations have a greater need for traveler information concerning different aspects of travel beyond traveler information that relates to their functional limitation(s); this greater need also relates to groups of people with covert functional limitations to which little consideration is usually given. Further, it is feasible to consider the need of traveler information generated by functional limitation(s) in providing traveler information in public transportation, and people with combinations of functional limitations that include loss of lower extremity skills and prevalence of poor balance are particularly in need of relevant traveler information.     

The effect of non-recreational transport cycling on use of other transport modes: A cross-sectional on-line survey

Accurate modelling of the health and environmental benefits of non-recreational transport cycling requires information about its effects on the use of other transport modes. Relevant research has not focussed on cycling for transport in a general context (as opposed to bikeshare), nor allowed for multi-modal trips. The influence of trip- and personal-characteristics on whether cycling replaces car-driving have yet to be considered. The present study aimed to address these research gaps. An on-line cross-sectional survey was completed by 1525 Australians who cycle for transport at least once per week. For the most recent trip completed (at least partly) by bicycle participants provided trip distance, and percentage travelled by car, public transport (PT), and walking. They also provided the percentage travelled by each mode for the same trip before taking up transport cycling; and a hypothetical future trip when riding is not possible. Compared to the same trip before, fifty percent of recent trips reduced car use, and around 1/3 eliminated a 100%-car trip. Reduced car use was significantly less likely for trips under 7.5 km, commuting, females, respondents under 55, and regular cyclists. Reduced car use was less likely for respondents who started riding because it is flexible, and more likely for those who started riding to avoid parking. Car-use was reduced by an average of 6.2 km per trip, and each bicycle-km cycled replaced 0.5 car-km. Participants report that since taking up cycling, even when they cannot use their bike, they use cars less and use PT more compared to before they took up cycling. Results suggest that previous studies underestimated the extent to which transport cycling replaces car travel, and highlights trip types and population groups to target with cycling promotion strategies. Information about the per-trip and per-bicycle-km replacement of car, PT and walking may be used for more accurate estimation of the benefits of transport cycling than has hitherto been possible.     

Impact of information and communications technology on transport

The impacts of information and communications technologies on transport are examined. First, the wider context of global change is outlined with the growth in the service and knowledge‐based economy, the breakdown of trade barriers, and the development of new patterns of travel. The more traditional views are briefly covered and discussed, and a case is made for longer term, more subtle direct and indirect effects of technological innovation on transport. Three spheres of influence are considered (production, living and working) to help structure the argument and to provide a framework within which to investigate the different information and communications technology applications in terms of their roles and impacts on transport. The review ends with three key unresolved questions that relate to the future of transport demand and analysis, and three further opportunities for using information and communications technology substantially to increase transport efficiency.     

汽车运输企业的融资策略

运输生产不改变劳动对象的属性或形态,是不具有实物形态的商品.其生产过程与消费过程同时进行,流动、分散、点多、线长、面广,是汽车运输企业的行业特性.它在发展中不同于其它行业的企业:其一,它是从事公路、城市道路货运和公路客运的企业,有较好的设施、设备,有一定的专业优势.大多是公有制企业和中小企业,属于劳动密集型,技术含量和附加值较低.其二,大多是老企业,有一定的品牌优势,生存、发展仍有前途.     

Knowledge-based systems for transport network analysis: A fifth generation perspective on transport network problems

This paper considers the formative steps in the development of an expert system for route selection in transport networks. It discusses the application of knowledge-based system (KBS) technology to the production of an expert system to provide route guidance information for some groups of urban travellers. There is a focus on the possibilities for applying a ‘fifth generation’ programming language, such as PROLOG, to the solution of network path selection problems, and the maintenance of a dynamic network database. There are significant arguments both for and against the use of the fifth generation languages, and the alternatives are discussed in speculative terms, on the basis of trials and experiments with PROLOG. The paper develops the specifications for a route guidance KBS for urban road travel, noting that one particular concern is that of providing the most suitable advice to a given traveller, rather than the system-wide rating of ‘best’ advice. Driver attitudes, behaviour, preferences, and vehicle characteristics differ widely, and the degree of satisfaction with any advice provided would depend largely on how closely the expert system could match the preferences of the individual traveller. Thus the system would need to gauge the characteristics of the user as well as those of the network under consideration. Further, prototype route guidance KBS are probably better directed at some clearly defined groups of urban travellers, such as commercial vehicle operations, rather than as community-wide systems.