沥青混凝土路面就地热再生施工工艺探讨

沥青混凝土路面就地热再生技术在废料利用、资源节约和生态环境保护等方面具有显著的技术和经济优势,具有广阔的应用前景。本文从沥青混凝土路面就地热再生主要工艺类型、加热方式、翻松方式、再生剂添加方式及施工过程等方面分析了沥青路面就地热再生技术施工工艺方面的要点及注意事项,以期为就地热再生技术的现场施工提供指导。     

沥青路面就地热再生技术在武黄高速公路养护工程中的应用与反思

为减少公路沥青路面养护工作中沥青废料的产生,循环利用沥青路面材料,武黄高速公路使用沥青就地热再生技术对路面进行了养护。经过5年的观测,试验路段总体情况良好,不足之处可通过优化方案设计、控制施工质量进行解决。     

高速公路改扩建工程废旧道路材料再生利用技术

本项目分别采用泡沫沥青冷再生和水泥稳定冷再生技术对现有道路进行改造扩建,针对废旧沥青路面各结构层材料铣刨工艺、回收路面材料性能、再生混合料组成设计和施工工艺等关键技术问题进行了系统研究,编制了沥青路面泡沫沥青冷再生技术规范和沥青路面再生施工技术指南,实现了资源循环利用、节能减排,经济社会效益显著,推广应用前景广阔。     

浅谈公路沥青路面的再生

沥青路面在使用一定时间后,出现的路面病害使其整体性能将不能满足路用要求,但作为路用材料仍有很高的利用价值。通过路面再生,可以使其重新满足路用性能要求,既能节省大量资金,也能保护环境、节约建筑材料、有利于废料的处理,实现循环经济发展模式和可持续发展。简单介绍了几种常用的道路再生施工技术,结合青海现有的公路现状及施工机械情况,重点推荐厂拌热再生技术的应用。     

公路工程沥青路面热再生施工技术的应用

公路沥青路面热再生技术是将破损路面的沥青混凝土现场再生或者回收再利用,能有效地节约资源。通过对沥青路面热再生技术的工艺及其优缺点的分析,可为该技术的改进和应用提供参考。     

就地热再生技术在高速公路沥青路面养护中的应用

就地热再生技术作为我国道路材料回收的一项重要技术,能够将废旧沥青经简单处理后用于损伤路面的修复。基于泉州某高速公路沥青路面就地热再生工程实例,首先通过实地调研研判原有道路工程路面性能,结合混合料回收评价对再生沥青混合料材料进行组成设计;其次对施工所涉及到的各类质量控制要点展开分析;最后对热再生的质量做出检验评价。     

沥青路面再生技术在公路改造维护中的应用

文章通过马歇尔击实试验,将沥青路面再生技术应用于公路项目旧沥青路面回收试验,提出了沥青混合料路面再生技术的特点和施工方法,并结合具体项目现场情况,阐述了沥青混合料再生技术的实用性。     

沥青路面热再生技术在柳南高速改扩建工程中的应用

沥青路面热再生技术是将废旧沥青混合料按一定条件进行二次利用的技术,是资源节约和绿色低碳的体现。文章通过对0、20%、30%、40%、50%、60%掺量下的废旧沥青混凝土进行再生沥青混合料配合比设计,研究再生沥青混合料的高温稳定性、水稳定性和低温抗裂性能,推荐合适的旧料掺量范围;根据柳南高速改扩建工程路面施工要求和质量要求,选取35%掺量的旧料进行再生沥青路面试验段铺筑。该研究对于促进沥青路面热再生技术在高速公路中的推广应用具有重要意义。     

隧道沥青路面环保铺筑技术研究

针对隧道沥青路面铺筑施工中存在的环境污染问题和路面结构的耐久性问题,《隧道沥青路面环保铺筑技术研究》课题开展了温拌降粘材料开发和使用性能研究与沥青路面施工过程中的通风技术研究,以减少隧道沥青路面铺装过程中的环境污染(包括施工过程污染和路面使用期间污染)、降低施工难度;同时研究了隧道沥青路面结构水泥混凝土基层与沥青层间的适宜粘结型式,力争提高隧道路面的使用耐久性。文章对该课题研究的内容、技术路线、试验方法及经济社会效益进行介绍,为隧道沥青路面铺筑施工提供借鉴。     

厂拌热再生沥青路面施工技术应用

在沥青路面使用一段时间后,由于车辆载荷或自然因素必然会产生较大的影响,进而产生老化、裂缝、车辙之类的问题,为了进一步提升厂拌热再生沥青路面施工技术的应用效果,结合相关人员的工作经验,对厂拌热再生沥青路面施工技术相关内容进行了详细探讨,分析可知厂拌热再生沥青路面施工技术要点包括回收旧沥青混合料、加热拌和、再生沥青混合料运输以及再生沥青混合料摊铺压实,厂拌热再生沥青路面施工质量控制的关键在于再生混合料拌和温度的控制及摊铺、压实工艺参数的控制。     

Survey of R&D in PRT systems

A survey of research and development in advanced transit has been made by Chalmers University of Technology in Gothenburg in cooperation with Trans21 in Boston. Summary findings are reported for fourteen academic research programs and ten development programs for PRT. An earlier version of this paper was presented at the International Conference of PRT and other Emerging Systems held in Minneapolis in 1996.     

The Impact of Container Type Diversification on Regional British Port Development Strategies

Abstract

Despite a concentration of container traffic in the southeast of the UK over the last few decades, regional ports are attempting new development strategies to capture or retain specific traffic segments. These include intra-European short-sea traffic and a potentially increasing feeder market. These trends are reflected in the movement of different container types, which result in a number of planning challenges related to changing infrastructural and operational requirements. This paper uses highly disaggregated data on container type movements to address three issues that can inform these planning challenges. First, the imbalance of trade resulting in empty container repositioning; second, the requirement for gauge-cleared rail routes to cater for the increasing proportion of high-cube containers; and third, the specialisation of European short-sea traffic at secondary UK ports. The results reveal the disproportionate repositioning of empty containers at Scottish ports and the importance of 45?ft, high-cube and pallet-wide containers at regional ports, highlighting their focus on intra-European short-sea traffic and raising difficulties relating to their lower quality of landside infrastructure (particularly rail) in comparison to the large south-eastern ports. The potential repercussions on hinterland infrastructure development raise questions about both public and private sector responses to regional port development.     

Modular route bus design – A method of meeting transport operation and vehicle manufacturing requirements

This research examines the problem of route bus specification and vehicle manufacturability. In order for bus operators to provide transport services, a range of vehicle configurations must be available from bus manufacturers, generating variety which has a negative impact on the manufacturing process. Larger part inventories, uncontrolled labour tasks and more troublesome maintenance are known impacts of this variety. This research identifies the functional necessities in route bus interior design and reduces the problems in bus manufacture and operation caused by specification diversity by proposing a modularised system of bus design. In particular, it makes recommendations as to how bus configuration should be carried out, ensuring an optimum mix of operational and manufacturing needs:

• 1.Determine user needs before the bus specification process.
• 2.Designs to be developed by the manufacturer in response to user needs.
• 3.This design should be standardised where possible, as suggested by the user needs.
• 4.Where user needs dictate product variations, apply a mass customisation approach to accommodate these needs.

The recommendations are communicated in design proposals for a modular bus interior, demonstrated by four cases designed to meet the present status quo of bus interior design and predictions for the future of the field.     

Optimization of bus stop locations for improving transit accessibility

A mathematical model is developed in this paper to improve the accessibility of a bus service. To formulate the optimization model, a segment of a bus route is given, on which a number of demand entry points are distributed realistically. The objective total cost function (i.e. the sum of supplier and user costs) is minimized by optimizing the number and locations of stops, subject to non‐additive users' value of time. A numerical example is designed to demonstrate the effectiveness of the method thus developed to optimize the bus stop location problem. The sensitivity of the total cost to various parameters (e.g. value of users' time, access speed, and demand density) and the effect of the parameters on the optimal stop locations are analyzed and discussed.     

Productive efficiency and ownership of urban bus services

The established ownership mix of urban bus operations in Australia provides a unique opportunity to investigate the productivity differences between public and private bus service supply. Using duality theory in economics which links economic indices of factor productivity to the cost structure of a firm, we develop empirical measures of total and partial productivity of inputs, and adjust the differences for the effects of ownership status and operating environment. The evidence supports the notion that private supply of public passenger transport in general has performed more efficiently in the past than public supply, although the differences in productivity need not continue in the future.     

管道风险分析指数评分法中分值调整初探

管道风险分析指数评分法中重要步骤之一就是确定影响管道事故因素的权重,各个管道风险因素在整个管道事故中所占的权重是不相同的。针对目前管道风险分析指数评分法基本假设之一（各因素的分值范围都是0～100分）,为了更加客观、准确、合理地反映各个风险因素对于管道事故的影响程度,提出并论述了依据层次分析法的数学逻辑性进行综合计算得出管道风险因素的权重,然后对评分法中各个因素的最高分值,根据其权重不同进行相应调整,从而增强评价者对风险因素的认识和评判能力,提高管道风险评价结果的准确性。     

Determinants of modal choice in freight transport

In the next few years, exciting developments in the field of freight transport are likely to occur. The Channel Tunnel will be perceived as giving railways much greater distance of operation, compared to the current train ferry to/from Great Britain. The further development of swap-body technology will allow easier modal transfer and the creation, in 1992, of a single market in Europe will transform the pattern of trade. All of these are likely to have significant impacts on modal choice, and hence modal split, in freight transport. Reappraisal by many firms of the modes of transport used is likely but will it result in a net transfer of freight from road to rail and, if so, to what extent? To answer such questions, an accurate and reliable method of predicting modal split is required. Research in the past has concentrated on the development of modal split models based on generalised costs. These fail to explain adequately the prevalence of road freight in the UK. From surveys of freight managers within industry, it is clear that models to date rely too heavily on the economic cost factor and too little on behavioural factors (Jeffs 1985). This paper derives from a recent study of freight transport modal choice from the standpoint of the transport decision-maker within the firm. It attempts to shed light on the actual parameters which should be incorporated into a modal split model. Many variables appear to exert an influence on modal choice decision-making process. However, it is possible to categorise them into six main groups, namely: customer-requirements; product-characteristics; company structure/organisation; government interventions; available transport facilities; and perceptions of the decision-maker him/herself. It is the interactions and inter-relationships between these which ultimately determine freight modal split. This study has shown that the relationship between the outcome of the transport decision process and the values of particular determinants of modal split is not straight-forward, due to the complexity and variety of interactions involved. Perhaps one of the main reasons for researchers' failure hitherto to develop a successful modal-split model has been the preoccupation with techniques that rely on the development of common metric (e.g. generalised cost), which has led to the exclusion of some important explanatory variables along quite different dimensions. Another important issue concerns the appropriate level of aggregation. In order not to reduce the explanatory power of the key variables, it is important to work at a disaggregate level, although this does make substantial demands on data. The use of factor analysis enables both the aggregation of information without loss of behavioural reality and the specification of variables in terms of a common metric. In conclusion, freight transport has usually been examined within too narrow a framework. It must be placed firmly within the context of the total industrial process. The demand for freight transport is directly influenced by the level, composition and geographical distribution of production and consumption activities. Freight flows are complex and so it is highly unlikely that a universal mode-choice model can ever be developed. Future research should, therefore, be directed towards developing partial models in response to specific needs of those involved in decision-taking in the freight sector.     

A century of evolution of the accessibility concept

The concept of accessibility has acquired numerous meanings along multiple dimensions during the century of its evolution. This essay argues for the salience of two dimensions: application-based and definition-based. In its application, accessibility has incorporated positive and normative dimensions which have varied in prominence over time. In its definition, accessibility has varied between a mode of evaluation incorporating measured mobility and proximity, on the one hand, and a predefined market basket of urbanist improvements to transportation and land use systems, on the other. Advocates of the accessibility shift should emphasize both the measured approach to accessibility and accessibility’s normative side.