铸就神话的人——中铁二局南宁大桥建设侧记

2009年3月15日，南宁大桥主桥胜利合龙的第15天，在葱郁的青秀山下，记者目睹了这座世界桥型首创的大跨度、曲线梁、非对称、外倾式钢箱拱桥的身姿。远远望去银白色的大桥在阳光照耀下，显得那么优雅，宛如一把巨大的“竖琴”安静地横跨在邕江上，正在等待过往的车辆奏出美妙的乐章；又如破茧待飞的银蝶准备在这山青水秀的绿城翩翩起舞。     

综合信息

正世界最大跨径公铁两用钢拱桥——沪通长江大桥天生港专用航道桥合龙1月21日,由中交第二航务工程局有限公司承建的世界最大跨径公铁两用钢拱桥——沪通长江大桥天生港专用航道桥胜利合龙。沪通大桥是我国沿海铁路大通道沪通铁路控制性工程,连接张家港市和南通市。大桥全长11公里,设计采用主跨1092米钢桁梁斜拉桥结构,为     

西部交通建设

张花高速公路张家界澧水特大桥合龙 6月11日,张（家界）花（垣）高速公路张家界澧水特大桥成功合龙,标志着大桥主体结构正式进入后续桥面施工阶段。澧水特大桥位于张家界市永定区和湘西自治州永顺县交界处,是目前湖南在建高速公路唯一一座悬索桥,也是张花高速公路的关键控制性工程之～。     

六律邕江大桥施工过程优化分析

不同的封铰时机,对钢管混凝土拱桥拱圈受力性能及拱圈线形会产生影响。为了研究钢管混凝土拱桥最佳封铰时机,文章以六律邕江大桥在建工程为依托,采用"过程最优,结果可控"的斜拉扣挂一次张拉施工优化计算方法,从钢管混凝土拱桥拱圈应力、拱圈线形、白噪声误差实验三方面对七种封铰方案进行对比分析研究。结果表明:六律邕江大桥7种封铰方案均可行,最佳封铰时机为封铰方案三;小跨径钢管混凝土拱桥扣索力、线形优化前后基本无差别。     

综合信息

海南规划2015年建成2小时旅游交通圈，我国首套移动式岸基船用供电系统启用，最大跨中承式双肢钢箱系杆提篮拱桥——明州大桥主拱合龙，国内首个水上搜救指挥中心成立     

湖南矮寨大桥建设创造“4个世界第一”

2011年8月20日上午，随着最后一颗铆钉装嵌到位，湖南连接重庆的矮寨特大悬索桥钢桁梁正式合龙，这标志着大桥主体结构的完工。矮寨大桥是长沙至重庆公路通道吉首至茶洞高速公路跨越矮寨大峡谷的一座特大型桥梁，建成后长沙至重庆将进入8小时经济圈。     

西部交通建设

2011年6月25日，渝利铁路控制性工程、世界上最大跨度的双线铁路斜拉桥——韩家沱长江大桥实现合龙，并将于2011年9月全面完工。韩家沱长江特大桥是渝利铁路中最具代表性的三座重要桥梁之一，全长近1．2公里，全钢梁结构，大桥主跨为432米，塔高180米。建成后，该桥将成为目前世界最大跨度的双线铁路斜拉桥，也是世界相近跨度每延米重量最轻的铁路斜拉桥。     

南宁大桥拱肋吊装线形控制与测量技术

文章通过介绍南宁大桥在拱肋吊装安装定位过程中的测量技术以及线形调整措施的工程实例,阐述了在非对称、大跨度、大吨位钢箱拱桥施工过程中拱肋的线形测量控制技术。     

综合信息

泰州长江大桥成功合龙 日前，随着最后一块钢箱梁吊装完成，创五项世界第一的泰州长江公路大桥成功合龙。     

成就跨越 铸就不凡——“世界第一拱”平南三桥诞生记

正引领进步,依靠创新;铸造工程,须得匠心。在世所瞩目的"世界第一拱"—荔浦至玉林高速公路平南连接线平南三桥的设计建造过程中,广西交通科技者以非凡创造铸就宏伟跨越。{宏伟工程世所瞩目}平南三桥是荔浦至玉林高速公路平南北互通连接线上跨越浔江的一座特大桥,全长1035米,主桥为跨径575米(计算跨径560米)的中承式钢管混凝土拱桥。"大桥的成功建设对推动大跨径钢管混凝土拱桥的应用及发展具有重要意义,以其在世界拱桥发展史上的独特地位     

寻找标杆

忆及改刊词,依然热血沸腾.沸腾的是我们"不断发现的事实"在不断地印证着我们的忧思、我们的定位、我们的目标、我们的理想.     

衬砌开裂隧道的稳定性分析及治理技术

隧道衬砌开裂将影响隧道的承载能力和使用安全.文章主要分析了铁路隧道开裂状况及原因,对裂缝宽度的影响程度进行了分级,利用断裂力学的方法研究了衬砌开裂隧道的稳定性,并提出了相应的裂缝治理技术.     

A fuzzy method for predicting the demand for rail freight transportation

The demand for rail freight transportation is a continuously changing process over space and time and is affected by many quantitative and qualitative factors. In order to develop a more rational transport planning process to be followed by railway organizations, there is a need to accurately forecast freight demand under a dynamic and uncertain environment. In conventional linear regression analysis, the deviations between the observed and the estimated values are supposed to be due to observation errors. In this paper, taking a different perspective, these deviations are regarded as the fuzziness of the system's structure. The details of fuzzy linear regression method are put forward and discussed in the paper. Based on an analyzes of the characteristics of the rail transportation problem, the proposed model was successfully applied to a real example from China. The results of that application are also presented here.     

Paying for harbor maintenance in the US: Options for moving past the Harbor Maintenance Tax

The Harbor Maintenance Tax is a fundamentally flawed maintenance funding mechanism for the critical US port system. Three alternatives were analyzed. User fee rates were estimated for either a national or regional tonnage based fee. Our results indicate that maintenance cost recovering regional fees could vary widely from about 10 cents per tonne to nearly 80 cents per tonne. A national rate would be about 30 cents per tonne. The large regional differences and affects on bulk shippers are likely to make implementing and maintaining cost recovering tonnage based fees infeasible. Two other mechanisms are considered. One possibility is to abolish the HMT without a replacement mechanism. The obvious strength of this approach is its simplicity, the weaknesses is that it is not budget neutral. Another possibility is to increase the federal diesel tax rate. One strength of the approach is the reasonable rate increase required to recover port maintenance costs (estimated between 0.278 and 0.315 cents per liter). An additional strength is that relatively inefficient fuel users will either make the largest share of the additional payments or the freight will shift modes to one that is more efficient. One weakness is that the rate has been unchanged since 1997, this points to the political difficulty involved in passing such a rate increase.     

Mathematical model for optimising the sequence for clearing snow from the manoeuvring area during winter operations

This article considers the optimisation of the sequence for clearing snow from stretches of the manoeuvring area of an airport. This issue involves the optimisation of limited resources to remove snow from taxiways and runways thereby leaving them in an acceptable condition for operating aircraft. The airfield is divided into subsets of significant stretches for the purpose of operations and target times are established during which these are open to aircraft traffic. The document contains several mathematical models each with different functions, such as the end time of the process, the sum of the end times of each stretch and gap between the estimated and the real end times. During this process, we introduce different operating restrictions on partial fulfilment of the operational targets as applied to zones of special interest, or relating to the operation of the snow‐clearing machines. The problem is solved by optimisation based on linear programming. The article gives the results of the computational tests carried out on five distinct models of the manoeuvring area, which cover increasingly complex situations and larger areas. The mathematical model is particularised for the case of the manoeuvring area of Adolfo Suarez Madrid—Barajas Airport. Copyright © 2016 John Wiley & Sons, Ltd.

Highlights
• Optimal sequence for clearing snow from the manoeuvring area of an airport.
• Contains optimising algorithms solved using CPLEX LP‐based tree search.
• Restrictions on partial fulfilment of operational targets applied to subsets of significant stretches, used for planning the operation of snow‐clearing machines.
• Model applied to the case of the manoeuvring area of Adolfo Suárez Madrid Barajas Airport.
• Conclusions are given on the results of the computational tests carried out. There are five models of the manoeuvring area which cover increasingly complex situations and larger areas.

     

循环气压缩机系统振动原因分析及消减措施

根据往复式压缩机系统运行的实际情况,通过定量计算,从理论上分析了压缩机系统产生振动的原因。通过采取针对性措施,包括对压缩机系统的工艺管线改造,增大循环气压缩机两列入口缓冲罐的直径、增加进气缓冲罐内附件、增加消振孔板、改造集气管和优化操作等措施,改善了机组及管系的振动状况,取得了较明显的减振效果,确保了机组的长期平稳运行。同时,随着振动降低,负荷提高,装置产量得到大幅提高,取得较显著的经济效益。     

Performance indicators for the road sector

Seeing the trend for public accountability of road administrations and noting the many reform efforts undertaken in transport sectors around the world, the OECD established a Scientific Expert Group on Performance Indicators for the Road Sector in 1996 to provide its member countries a framework for assessing road administrations' performance. The results of the Expert Group's work is presented in this paper.Fifteen indispensable, forty primary, and thirty-five secondary indicators are proposed to portray the road sector from different perspectives. They are designed to be changed in response to human needs and technological development and supplemented by country specific indicators. In keeping with this approach and in support of one of the maxims of the Expert Group that 'useful performance indicators are those which are used', an application in the form of a Field Test is now in progress by an OECD task force.The Performance Indicators proposed are grounded in a mental model adopted by the Expert Group. This model is management by results model, and is useful as a theoretical tool in the many highly fluid contexts in which restructuring is moving forward. In the model, the products and services are judged by standards or criteria; outcomes – derivatives of products and services through user interface – are judged relative to objectives and user satisfaction. The achievement of objectives, however, is not proposed as the only or even primary basis of evaluation. The situation is more abstract and complex. Therefore, the various uses of Performance Indicators – including the opportunities to assist road administrations in becoming learning organizations – are given much emphasis in the paper. The views and conclusions in the paper are those of the author and should not be attributed to the World Bank or its affiliated organizations.     

汽车租赁的收益管理

曾名噪一时的美国人民捷运航空公司前CEO唐纳德伯尔在1996年公司破产后总结原因时说:"1981年～1985年期间我们是一个充满活力和盈利的公司.随后我们开始从顶峰跌到每月亏损5千万美元的地步.我们公司没有任何变化,可是美国航空公司却将他们的收益管理渗透到我们的每一个市场.当美国民航以终结者的面目出现时,我们盈利的日子就彻底结束了.我们丧失了防卫能力,末路到了,因为他们总能够比我们价格或即将公布的价格要低."     

Willingness to pay for public transportation options for improving the quality of life of the rural elderly

Transportation for the rural elderly is an increasing concern as baby boomers age and young people continue to exit rural communities. When the elderly are no longer able to drive, they rely on alternative forms of transportation, including public transportation systems. Currently, such systems are usually not good substitutes for driving a private car, especially in rural areas. Because expanded rural transportation systems would likely be funded by taxpayers, an understanding of their preferences and willingness to pay (WTP) for non-medical transportation options is essential. To help understand WTP and preferences, a choice experiment survey was administered to taxpayers in three counties (Atascosa, Polk, and Parker) in Texas. Results indicate taxpayers’ value transportation services for the elderly and are willing to support them. They value more flexible options over base levels of the attributes presented, but they may not always prefer the most flexible options. Respondents’ WTP for the same transportation attribute was similar across counties, but differences in socio-demographic coefficients suggest that transportation systems may need to be customized to meet local needs. Furthermore, county residents’ WTP may not cover the cost of desired improvements to the transportation systems.     

Approximation algorithms for the bid construction problem in combinatorial auctions for the procurement of freight transportation contracts

Trucking companies (carriers) are increasingly facing combinatorial auctions conducted by shippers seeking contracts for their transportation needs. The bid valuation and construction problem for carriers facing these combinatorial auctions is very difficult and involves the computation of a number of NP-hard sub problems. In this paper we examine computationally tractable approximation methods for estimating these values and constructing bids. The benefit of our approximation method is that it provides a way for carriers to discover their true costs and construct optimal or near optimal bids by solving a single NP-hard problem. This represents a significant improvement in computational efficiency. We examine our method both analytically and empirically using a simulation based analysis.