基于层次分析法的涵洞技术状况评定

文章针对在役涵洞技术状况评定问题,提出基于层次分析法的涵洞技术状况评定方法,对涵洞评价指标、构件评价标准和单项指标控制标准进行了研究,并结合工程实例,验证了基于层次分析法的涵洞技术状况评定的可行性和科学性。     

多年冻土涵洞的设计

结合多年冻土地区冻土特征,分析了多年冻土地区涵洞产生病害的原因,提出了涵洞的设计原则,在多年冻土段落采用波纹管涵代替盖板涵,提出了波纹管涵的施工要求,总结了波纹管涵的优缺点。     

基于FLAC3D的高填方路堤通道涵洞受力特性数值分析

文章以厦蓉高速公路广西境内灌阳至全州段K13＋710通道涵洞为工程实例,利用FLAC3D（快速拉格朗日分析）软件对高填方路堤中的顶板通道进行数值仿真分析,总结了高填方路堤通道涵洞的受力特性,并提出了通道涵洞设计施工中应注意的问题。     

平阿高速公路黄土区涵洞病害特征调查及防治对策探讨

涵洞病害是高速公路在黄土区域中典型病害之一,也是高速公路在运营期间的重点维护和防治对象。本文针对青海省境内平阿高速公路在穿越黄土区域段的51座涵洞进行了实地调研,基于此总结了青海省黄土地区平阿公路涵洞出现的7种典型病害类型,即涵洞下沉、基础开裂、护锥翼墙沉降开裂或倾斜错位、涵节错位或填缝脱落、内部或进出口积水淤塞、涵背填土塌陷、涵顶路面开裂等。对涵洞的基本病害特征进行了分析,并对不同病害类型提出了相应的防治对策与建议。该研究成果可以加深对黄土区公路涵洞病害机理的认识,对黄土地区高速公路涵洞病害的勘察、防治和施工具有一定的指导意义。     

公路工程桥梁涵洞施工的质量管理研究

涵洞、桥梁工程是公路工程中最重要的建设内容之一,其施工质量好坏直接关系到整个公路工程的质量。因此,在桥梁涵洞的施工期间,应该严格对施工质量进行监管。文章分析了桥梁涵洞施工中的影响因素及控制措施,并根据具体实践中出现的难题,提出了相应的质量控制方法。     

粉喷桩处理涵洞软基实例的设计计算

河南省少林寺至洛阳高速公路K7+276涵洞的软基承载力不满足设计要求,从承载力的角度对该涵洞软基进行加固设计计算,提出一个理论公式法解决涵洞软基加固的计算模式.     

多年冻土地区涵洞施工工艺探讨

施工过程是实现设计意图,保证工程质量的重要环节,施工工艺不合理常常导致涵洞工后破坏。涵洞工程数量大,工程分散。施工单位应根据设计要求、技术装备、材料来源,制定施工计划,合理安排进度,科学组织施工。本文概述了多年冻土地区涵洞施工工艺,在此基础上根据不同的设计原则对各种施工工艺进行了较为详尽的探讨,并提出了相应的具体工程操作步骤。     

涵洞跳车的原因与防治措施

对涵洞跳车的原因进行分析,并提出了防治措施.     

换填法在涵洞软土地基施工中的应用

文章结合广西某二级公路涵洞施工实例,分析了软土地基对涵洞施工的影响,介绍了换填法在涵洞软土地基中的具体应用方法与要点,为类似工程建设提供经验借鉴。     

青藏高原多年冻土地区涵洞基础稳定性调查及分析

本文通过对于国道G109线(青藏公路)路段的公路工程概况和该地区的自然地质条件的调查结果的分析,以及青藏公路涵洞使用状况调查方法与调查结果的探讨,在此基础上论述了多年冻土区涵洞破损类型与特征,并对其发生的深层次原因进行了较为详尽的总结,提出针对多年冻土地区涵洞破坏原因,应从4个方面入手,采取措施进行病害防治:减小工程对多年冻土的热扰动;消除或削弱季节活动层的冻胀和融沉;增强涵洞结构抵抗和适应冻融变形的能力;消除或减小涵底渗流。     

International private and public reinforcing dependencies for the innovation of automotive emission control systems in Japan and USA

In the beginning of the 1970s, the economies of USA and Japan were growing fast and environmental pollution was increasing to alarming levels. As passenger car emissions were found to be significant and rapidly increasing, their reduction was specially targeted. Following a bill passed by US Congress in 1968, requirements were set in 1970 for the vehicle manufacturers to reduce the emissions of carbon monoxide (CO) and hydrocarbons (HC) with 90% by 1975, and nitrogen oxides (NO_x) with 90% by 1976. These requirements were soon adapted to the Japanese regulatory framework, and were known in both countries as the “Muskie Act” or “Muskie Law” after the senator who developed the original bill.The new requirements spurred tremendous research and development efforts. Car manufacturers and research institutions in USA, Japan and Europe investigated and developed alternative solutions, including gas turbine and steam engine vehicles. California, the USA state with the most severe air quality problems and the only state at the time allowed to establish more strict requirements than federal regulation, established requirements implying the use of oxidation catalysts in 1975 and three-way catalysts (TWC’s) in 1977. Japan as a nation adopted similar requirements 1976 and 1978. Export of cars from Japan to USA increased rapidly. The rest of USA adopted emission standards similar to California’s only in 1981, timing USA vehicle sales rebound after the energy crisis and grave economic downturn. Strict requirements were thus established only after more than a decade of civic and legal processes between federal authorities, the car manufacturers and NGO’s.The history of vehicle development is one of cooperation and competition. This paper argues that the international cooperation on different levels of society (government, industry and science) together with commercial competition between the two countries was strong, continuous and instrumental in enabling the development of technology, appropriate regulation and infrastructural changes and thus created a market for cleaner cars and effectively reduced emissions from the growing vehicle fleet. In other words, the introduction of TWCs was reinforced by the simultaneous development of mitigating technology in two car producing countries competing for market space.     

The changing face of parking-related data collection and analysis: The role of new technologies

Current trends in requirements for parking related information and in the availability of data are reviewed. Important influences include the increased need for data to assist in the efficient operation and management of parking stock and to assess the impact of parking on the local network and economy. New sources of data are described, particular attention being given to the availability of data as a byproduct of parking management systems and computerised enforcement systems. The use and performance of audio, video and data loggers in parking surveys is discussed as is the role of computers in questionnaire surveys. New methods of analysis involving spreadsheets, graphics and analysis software, links with databases and simulation models are outlined.     

Traveler delay costs and value of time with trip chains, flexible activity scheduling and information

The delay costs of traffic disruptions and congestion and the value of travel time reliability are typically evaluated using single trip scheduling models, which treat the trip in isolation of previous and subsequent trips and activities. In practice, however, when activity scheduling to some extent is flexible, the impact of delay on one trip will depend on the actual and predicted travel time on itself as well as other trips, which is important to consider for long-lasting disturbances and when assessing the value of travel information. In this paper we extend the single trip approach into a two trips chain and activity scheduling model. Preferences are represented as marginal activity utility functions that take scheduling flexibility into account. We analytically derive trip timing optimality conditions, the value of travel time and schedule adjustments in response to travel time increases. We show how the single trip models are special cases of the present model and can be generalized to a setting with trip chains and flexible scheduling. We investigate numerically how the delay cost depends on the delay duration and its distribution on different trips during the day, the accuracy of delay prediction and travel information, and the scheduling flexibility of work hours. The extension of the model framework to more complex schedules is discussed.     

Port Economics,Policy and Management: Content Classification and Survey

This paper presents a taxonomy and analysis of the content of published research in port economics, policy and management (port studies). The recent increase of these publications suggests a growing interest in the study of ports. However, the research characteristics and directions of this research field are unidentified. This paper provides a systematic analysis of port studies published during the period 1997–2008. A comprehensive cross-citation and analysis of the themes, approaches and findings of all 395 relevant journal papers identifies the extent to which the research field is maturing, and the leading papers. This paper also presents an extensive analysis of the content, based on the classification of all port studies into seven research themes. For each theme, research topics, widely used research questions, concepts and research methods and the most important research findings are discussed. Finally, we identify emerging research challenges and research questions that still need to be answered.     

基于GPS和GSM的清管器智能跟踪系统

为了在清管施工中实时跟踪清管器,设计一种基于GPS系统和GSM通信系统的智能清管器跟踪系统,系统包括发射机、中继器和监控系统。发射机搭载在清管器上持续发射电磁信号和静磁信号,中继器预先埋设在设定的跟踪点接收和转发通过信息;清管器通过跟踪点时,中继器接收发射机发出的信号,精确识别出清管器并将通过时间和跟踪点GPS位置信息通过GSM网络发送至监控系统;监控系统接收到信息后,在监控界面地图上实时显示通过位置和通过时间。清管器卡堵时,系统可及时在地图上指示卡堵区间和到达卡堵现场路径。现场应用表明:该系统实现了清管器智能跟踪,通过时间和通过位置记录精确,降低清管施工中安全风险,节约成本。     

Rural mobility and mode choice: Evidence from the 2001 National Household Travel Survey

This article uses data from the 2001 National Household Travel Survey (NHTS) to compare travel behavior in rural and urban areas of the U.S. As expected, the car is the overwhelmingly dominant mode of travel. Over 97% of rural households own at least one car vs. 92% of urban households; 91% of trips are made by car in rural areas vs. 86% in urban areas. Regardless of age, income, and race, almost everyone in rural areas relies on the private car for most travel needs. Mobility levels in rural areas are generally higher than in urban areas. That results from the more dispersed residences and activity sites in rural areas, which increase trip distances and force reliance on the car. Somewhat surprisingly, the rural elderly and poor are considerably more mobile than their urban counterparts, and their mobility deficit compared to the rural population average is strikingly less than for the urban elderly and poor compared to the urban average. Data limitations prevented a measurement of accessibility, however, and it seems likely that rural areas, by their very nature, are less accessible than urban areas, especially for the small percentage of car-less poor and elderly households.     

Integrated modeling of car/motorcycle ownership, type and usage for estimating energy consumption and emissions

Devising effective management strategies to relieve dependency on private vehicles, i.e. cars and motorcycles, depends on the ability to accurately and carefully examine the effects of corresponding strategies. Disaggregate choice models regarding the ownership, type and usage of cars and motorcycles are required to achieve this. Consequently, this study proposes integrated car and motorcycle models based on a large-scale questionnaire survey of Taiwanese owners of cars and motorcycles, respectively. Incorporating gas mileage and emission coefficients for different types of cars and motorcycles into the proposed models can enable the estimation and comparison of reductions in energy consumption and emissions under various management strategies. To demonstrate the applicability of the proposed integrated models, scenarios involving 10% and 30% increases in gas prices are analyzed and compared. The results indicate that gas price elasticities of cars and motorcycles are low, ranging from 0.47 to 0.50 for cars and 0.11 for motorcycles. Additionally, a high ratio of discouraged car users shifting to use of motorcycles neutralizes the effects of increased gas price in reducing energy consumption and emissions. Pollution of CO and HC even slightly increased because motorcycles are much more polluting in terms of CO and HC. At last, the reductions of energy consumption and emissions under 10% and 30% increase (or decrease) in other manipulating variables are also estimated and compared. The countermeasures for reducing ownership and usage of cars and motorcycles are then recommended accordingly.     

Driving behaviour at motorway ramps and weaving segments based on empirical trajectory data

In the vicinity of ramps, drivers make route choices, change lanes and in most cases also adjust their speeds. This can trigger anticipatory behaviour by the surrounding vehicles, which are also reflected in lane changes and/or changes in speed. This phenomenon is called turbulence and is widely recognised by the scientific literature and various design guidelines. However the knowledge about the characteristics of turbulence is limited. This study investigates the microscopic characteristics of driving behaviour around 14 different on-ramps (3), off-ramps (3) and weaving segments (8) in The Netherlands, based on unique empirical trajectory data collected from a video camera mounted underneath a hovering helicopter. The data analysis reveals that lane changes caused by merging and diverging vehicles create most turbulence, that an increase in the amount of traffic results in a higher level of turbulence and that an increase in the available length for merging and diverging results in a lower level of turbulence. The results of this study are useful for improving the road design guidelines and for modelling driving behaviour more realistically.     

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.     

交通运输发展水平评价指标体系构建及优化研究

交通运输业是经济社会实现快速发展的重要保障,是实现国家和区域可持续发展的必要基础,承担着推动经济社会实现高质量发展的历史使命。本文介绍了交通运输发展的内涵,结合建成小康社会、生态文明建设、交通强国建设等战略目标对交通运输发展总体要求,对评价指标体系进行了初步构建。在此基础上对初选评价指标体系进行了"四个检验",同时运用变异系数、相关系数等方法进行了评价指标体系的优化调整。本文所研究构建的评价指标体系及优化调整方法可为行业管理部门开展相关工作、制定相关政策提供参考。