桥梁水上钢栈桥、钢平台设计及有限元仿真分析

文章以某深水桥梁施工钢栈桥及钢平台为研究背景,依据水下桩基及水下承台施工作业的要求进行钢栈桥及钢平台设计,并根据钢栈桥及钢平台在桩基施工及承台施工过程中不同工况下的最不利状态,对桥梁水上钢平台结构进行了有限元仿真分析计算。结果表明,该钢栈桥及钢平台整体受力性能满足使用要求。     

重载型贝雷梁钢栈桥和钢平台施工技术与监测维护分析

文章以田阳县东江二桥5号主墩重载型钢栈桥和钢平台应用为背景,针对钢栈桥和钢平台水上施工及监测维护问题,阐述了重载型贝雷梁钢栈桥和钢平台的施工技术与监测维护方案,可为类似工程施工与监测维护提供借鉴。     

Midas Civil在钢栈桥结构设计中的应用

文章以崇左龙江大桥为例,利用Midas Civil软件建立有限元模型,通过最不利工况,模拟分析钢栈桥结构受力体系,同时计算了钢管桩的入土深度,并通过应变片对钢栈桥关键位置进行了运营监测。结果表明,Midas Civil软件对施工单位判断钢栈桥结构设计的合理性提供了有力依据,其三维展示效果能够使现场管理人员更好地掌握钢栈桥结构特点。     

钢栈桥及钢平台在水中桩基施工中的应用

文章结合梧州至柳州高速公路土建工程№A01-7标段枫木界1号大桥水中桩基施工实例,介绍了钢栈桥及钢平台的设计方案,并针对水中桩基施工难点,分析了钢栈桥及钢平台施工技术。     

深水无覆盖层河床钢栈桥施工技术

文章以浔江特大桥钢栈桥施工为例,对深水无覆盖层河床钢栈桥施工技术进行了经验总结,其施工技术方法与措施可供类似工程参考。     

贝雷桁架及钢管桩组合在施工钢栈桥中的运用

作为钢栈桥项目施工的重要方式,贝雷桁架及钢管桩的组合应用,不仅能简化栈桥结构,而且具有运输方便、架设快速、分解容易、经济效益高的特点。文章以田隆公路贝雷片钢栈桥专项施工项目为例,介绍了贝雷桁架及钢管桩组合施工要点及质量控制策略。     

“钓鱼法”搭设钢栈桥在桥梁施工中的应用

汕湛高速揭博项目T3合同段横江水库特大桥主桥横跨横江水库。为了满足水中墩施工需要,在库区南北两岸搭设钢栈桥一座。栈桥长537m,宽8m。由于水库库区大型船舶和浮吊无法进入,只能采用"钓鱼法"进行钢栈桥的搭设。就"钓鱼法"搭设钢栈桥施工过程中有关场地处理、钢管桩振打、贝雷梁安装就位进行了细致的归纳和总结,以期为类似施工环境下的桥梁施工提供借鉴和参考。     

月亮岛钢栈桥施工设计方法探讨

文章以广西防城港市月亮岛钢栈桥施工为例,通过分析该地区的水文气象、地质条件、地形地貌等施工条件环境,阐述该钢栈桥施工设计思路、工艺流程及操作要点等,以期为类似工程提供参考。     

拉圩大桥临时钢栈桥设计与分析

文章针对拉圩大桥的工程特点,设计了一座"贝雷梁+型钢形式"钢栈桥,并利用Midas软件对其常见行车荷载工况下结构的组合应力、剪应力、位移等进行计算分析,同时,对桥台承载力也进行了计算。结果表明,该钢栈桥的设计安全合理。     

无覆盖层深水钢栈桥施工技术分析

文章以浔江特大桥栈桥施工为背景,结合工程特殊水文地质情况,通过施工技术方案比选,确定了钢栈桥施工工艺及技术措施,成功解决了在水深、流速大、汛期水位暴涨、漂浮物多,且河床无覆盖层的陡峭或倾斜坚硬裸岩层的高位栈桥施工难题。     

Passenger conveyor economics

Operating and capital costs for a high speed conveyor are estimated from cost data for low speed conveyors and from estimates for high speed designs. Unit costs are developed with reference to theoretical and practical conveyor capacities, and to the effect of traffic peaking on average utilization. User benefits are modelled as the change in consumers surplus arising from the introduction of a conveyor on a linear street as an alternative to walking. Cost and benefits vary widely depending on system design and location and on characteristics of travellers. Benefit measurements should reflect the effects on travel demand of a proposed installation, changes in value of time with changes in mode, and the effects of benefit “dilution” associated with limitations on access to the conveyor.     

Impacts of fuel quality on indoor environment onboard a ship: From policy to practice

Environmental considerations, concerning the negative impacts of ship exhaust gases and particles on ambient air quality, are behind the requirements of cleaner marine fuels currently applied in designated emission control areas (ECAs). We investigated the impact of a ship operating on two types of fuel on the indoor air quality onboard. Gaseous and particulate air pollutants were measured in the engine room and the accommodation sections on-board an icebreaker operating first on Heavy Fuel Oil (HFO, 1%-S), and later Marine Diesel Oil (MDO, 0.1%-S). Statistically significant decrease of SO₂, NOx, PM_2.5 and particle number concentration were observed when the ship was operating on MDO. Due to the higher content of alkylated PAHs in MDO compared to HFO, the concentration of PAHs increased during operation on MDO. The particulate PAHs classified as carcinogens, were similar to or lower in the MDO campaign. Chemical analysis of PM_2.5 revealed that the particles consisted mainly of organic carbon and sulfate, although the fraction of metals was quite large in particles from the engine room. Principal Component Analysis of all measured parameters showed a clear difference between HFO and MDO fuel on the indoor environmental quality on-board the ship. This empirical study poses a first example on how environmental policy-making impacts not only the primary target at a global level, but also brings unexpected localized benefits at workplace level. The study emphasizes the need of further investigations on the impact of new marine fuels and technologies on the indoor air environments on board.     

客运专线铁路隧道瞬变压力现场试验及单维效应分析

客运专线铁路隧道的设计与研究中必须要考虑高速列车在隧道中运行时所诱发的空气动力学效应的影响,其中应重点考虑瞬变压力对旅客乘车舒适度的影响。文章通过遂渝线提速(200 km/h)综合试验中的隧道空气动力及结构动力学试验,对200km/h动车组通过隧道时隧道内瞬变压力的现场试验数据及其单维效应进行了分析与研究。     

Bicycle parking: a systematic review of scientific literature on parking behaviour,parking preferences,and their influence on cycling and travel behaviour

ABSTRACT

Cycling is experiencing a revival in many cities. Research has focused on the determinants of cycling – in particular the role of the built environment and road infrastructure. Bicycle parking has received little attention – even though bicycles are parked most of the time. This article reviews the scientific literature on bicycle parking and identifies existing gaps in research and knowledge. The review analyses 94 peer-reviewed papers identified through a search in Scopus and Web of Science, in December 2017. The annual number of papers increased 15-fold between 1995 and 2017. Overall, the level of evidence on the importance of bicycle parking is limited. The majority of studies are based on cross-sectional data with the presence of parking as a binary independent variable. Most studies focus on bicycle parking at public transport stops and at work places. Few studies report on bicycle parking throughout cities, and hardly any on parking at residential locations. Bicycle parking supply and quality appears to be a determinant of cycling for current and potential cyclists. Our findings can serve as input for an evidence-based debate on the role of bicycle parking. For practitioners, our research supports investment in bicycle parking, but acknowledges that a proper evaluation of such initiatives needs to be conducted to increase the level of evidence.     

地质顺层偏压隧道围岩压力及其分布特点的试验研究

结合渝怀铁路渔塘湾隧道所处的地质顺层偏压特点,按照相似理论,对地质顺层岩体作用于隧道衬砌结构上的偏压载荷进行了模型试验,初步得出了地质顺层偏压隧道围岩压力的分布特点及其与不同顺层倾角之间的变化关系,并就顺层岩体隧道结构的形式和支护措施进行了探讨。     

Stability of transportation networks under adaptive routing policies

Growing concerns regarding urban congestion, and the recent explosion of mobile devices able to provide real-time information to traffic users have motivated increasing reliance on real-time route guidance for the online management of traffic networks. However, while the theory of traffic equilibria is very well-known, fewer results exist on the stability of such equilibria, especially in the context of adaptive routing policy. In this work, we consider the problem of characterizing the stability properties of traffic equilibria in the context of online adaptive route choice induced by GPS-based decision making. We first extend the recent framework of “Markovian Traffic Equilibria” (MTE), in which users update their route choice at each intersection of the road network based on traffic conditions, to the case of non-equilibrium conditions, while preserving consistency with known existence and uniqueness results on MTE. We then exhibit sufficient conditions on the network topology and the latency functions for those MTEs to be stable in the sense of Lyapunov for a single destination problem. For various more restricted classes of network topologies motivated by the observed properties of travel patterns in the Singapore network, under certain assumptions we prove local exponential stability of the MTE, and derive analytical results on the sensitivity of the characteristic time of convergence to network and traffic parameters. The results proposed in this work are illustrated and validated on synthetic toy problems as well as on the Singapore road network with real demand and traffic data.     

基于LEAP模型的佛山市交通碳排放研究

随着城市化的发展,珠三角城市交通能源消耗和碳排放迅速增长。为了探讨珠三角城市低碳交通的发展方向,本文采用LEAP模型,以珠三角的佛山市为例,模拟了不同情景下交通总量、陆运和水运的能源消耗、能源结构和碳排放由2011至2030年的变化情况;并据此提出了珠三角城市低碳交通发展对策。结果表明:水运在交通运输中所占份额逐渐被陆运替代,将形成陆运为主、水运为辅的交通模式;在交通总量、陆运和水运等的交通能耗及碳排放方面,低碳情景均小于基准情景,且呈水运小于陆运的态势;而清洁能源使用比重的增加则有利于交通领域的低碳发展。珠三角城市低碳交通发展需关注陆运交通,提高清洁能源在陆运中的使用比重,优化陆运与水运的交通布局,提高运输及能源利用效率。     

Airlines’ reaction to high-speed rail entries: Empirical study of the Northeast Asian market

We investigate the impact of the commencement of high-speed rail (HSR) services on airlines’ domestic available seats on affected routes in China, Japan, and South Korea. The study is based on a dataset covering the 1994–2012 period. We use the propensity score matching method to pair HSR affected routes with routes without HSR services. The difference-in-difference approach is used to estimate the impact of HSR entry. We find that HSR entries may, on average, lead to a more significant drop in airlines’ seat capacity in China than in Japan and Korea given similar HSR service speed. In China, HSR services with a maximum speed about 200 km/h can produce strong negative impacts on medium-haul air routes but induce more air seat capacity on long-haul routes. HSR services with a maximum speed of 300 km/h have little extra impact on medium-haul routes but a strong negative impact on long-haul routes. Finally, although HSR has a strong negative impact in Japan’s short-haul and medium-haul air markets, little impact is observed in its long-haul markets.     

大城市中心区实施拥堵收费的影响评价研究

文章在分析大城市中心区拥堵收费实施条件与方式的基础上,定性分析实施拥堵收费对居民出行行为以及中心区动静态交通的影响,最后提出基于模糊评价理论的中心区拥堵收费影响评价模型.     

Risk Management in Motorway PPP Projects: Empirical-based Guidelines

Abstract

This paper deals with the topic of risk management in Public Private Partnership (PPP). The analysis of the related literature reveals that risks must be analyzed and managed on a context-specific approach, and that there is a lack of a comprehensive study on the appropriate risk mitigation strategies for each risk embedded in PPP projects. Focusing on the transport sector, based on the results of a Delphi survey, the paper provides guidelines for both public and private parties in defining a list of significant risks in PPP motorway projects, and identifying for them both the effective allocation and the suitable mitigation strategies. Results of the Delphi survey have been compared with the common practices on risk management applied in eight real motorway PPP projects.