China High-Speed Railway
As the economic grow, intercity travel demand has incread dramatically in the Greater China Area. Traditional railways can hardly satisfy the pasnger and freight travel demand, high speed rail is hence propod and constructed after 1990s. This study aims to integrate current development of both rail-bad and Maglev high speed trains in this area. From 1997, Taiwan kicked-off its high speed rail construction by importing the technology of Japane Shinkann. The Taiwan High Speed Rail is a 15-billion US dollars project. To save the cost of construction and management, the BOT model was applied. Though not totally satisfied, this project is still successful and ready to operate in the 4th quarter of 2007. China is preparing its high speed rail rvices by upgrading current networks. The capacity and operating speed are all incread after 5-times system upgrade. The 6th upgrade will be initiated in 2006. By then, trains will run at a speed of 200km/h in a total distance of 1,400km in 7 different routes. From the white paper published by the Ministry of Railway in China, there will be totally 8 rail-bad High Speed Train rvices. Four of them are North-South bound, and four of them are East-West bound. 5 of the 8 High Speed Rails 爽口萝卜的做法
are now under construction, the first line will be finished in 2009, and the 2nd one will be in 2010. By 2020, there will be totally 12,000 kilometers high speed rail rvices in China. The 250 billion US dollars construction cost still leaves some uncertainties for all the projects. Finally, the future of the Maglev system in China is not so bright as rail-bad. Shanghai airport line could be the first, also the last Maglev project in China if the approved Shanghai-Hangzhou line cannot rai enough 4.4 billion dollars to build it.
Steel rail composition
Steel rail is compod of iron, carbon, mangane, and silicon, and contains impurities such as phosphorous, sulphur, gas, and slag. The proportions of the substances may be altered to achieve different properties, such as incread resistance to wear on curves.
The standard configuration for North American rail rembles an upside down T. The three parts of T-rail are called the ba, web, and head. The flat ba enabled such rail to be spiked directly to wooden crossties; later, rail was placed on the now-standard steel tie plate. While the proportions and preci shape of rail are subject to constant analysis and
refinement, the basic T-ction has been standard since the mid-19th century.
Weight
The most common way of describing rail is in terms of its weight per linear yard <the historic British unit of length>, which is a function of its cross ction. In the late 19th century, rail was produced in a range of ctions weighing between 40 and 80 lbs. per yard. Weights incread over time, so that rail rolled today weighs between 112 and 145 lbs. <The Pennsylvania Railroad's 155-lb. ction, ud for a time after World War II, was the heaviest ud in the U.S.>
Jointed rail gments
The length of standard rails has historically been related to the length of the cars ud to transport them. From an early range of 15-20 feet, rail length incread with car size until a standard of 39 feet <easily accommodated by the once-common 40-foot car> was reached. Even with the advent of today's longer cars, 39 feet has remained the standard for rail owing to limitations in steel mills and ea of handling.
学习美术 The joints in rail — its weakest points — can make for a rough ride, and are expensive
to maintain. Individual rails are joined with steel pieces called joint <or angle> bars, which are held in place by four or six bolts. Today, the six-bolt type, once rerved for heavy-duty applications, is standard. The bolts in a joint bar are faced alternately outward and inward to guard against the remote possibility that a derailed car's wheel would shear them all off, causing the rails to part. Transition between rails of two different weights is achieved with special angle bars. In territory where the rails rve as conductors for signal systems, bond wires must be ud at the joints to maintain the circuit.
Welded rail
The troublesome nature of rail joints prompted the most easily recognized advance in rail technology: the adoption of continuous welded rail <CWR>.
From its early u on a handful of roads in the 1940's, welded rail has come to be preferred for almost all applications. It is produced by welding standard 39-foot <or newer 78-foot> gments together into quarter-mile lengths at dedicated plants.
The rails are transported to where they're needed in special trains, which are pulled slowly out from under the rail when it is to be unloaded. When in place, CWR is often field-
welded into even greater lengths. Much jointed track survives becau of the long lifespan of even moderately ud rail, and becau the specialized equipment needed for CWR installation is not economical for short distances.
师的组词 Managing the expansion and contraction that comes with temperature change is important with CWR. To avoid expanding and potential buckling when in rvice, welded rail is laid when temperatures are high <or is artificially heated>. Rail anchors clipped on at the ties keep the rail from getting shorter as it contracts with falling temperatures. Thus constrained, it shrinks in cross ction <height and width>, but not in length. Becau it's in tension, welded rail is treated with care during trackwork in cold weather.
Maintaining and reusing rail
Under heavy traffic, rails get worn down, although their life can be extended by grinding the head back to the proper contour.
Rail no longer suited for main-line u may still have some light-duty life in it and is often relaid on branches, spurs, or in yards. Main-track reduction projects are also sources of such "relay" rail.
When rail wear is uneven at a given location <such as a curve>, rail may be transpod from one side to another to get maximum u out of it.
撩妹宝典中国高速铁路
随着经济的增长,城市间的旅行需要在中国地区飞速增长.传统铁路已经很难满足旅客的货运的需求,因此自1990年起高速铁路被提上议程并着重建设.这个研究的目得是在于这个区域内的基本线路和高速磁悬浮列车得到发展 自1997年起,##通过引进日本新干线技术开始进行它的高速铁路建设,##的高速铁路是一项耗资150亿美元的工程,为了节省建设和管理的开支,他们采用了BOT的经营模式,尽管并不是完全的满意,但是这项工程还是很成功的,并且预计在2006年底实行运转,中国正在通过提升现在的网络系统为自己的高速铁路服务而做准备,在第五次系统提升之后,铁路的接纳能力和运转速度都得到了增长.第六次大提速将于2007年进行,到那时火车将在7条不同的铁路线路上,全程1400公里,以每小时200公里的速度运行.中国铁道部发布的官方报告上声称将共有八条基本铁路为你服务.其中有四条是南北纵向的,另外四条是东西横向,八条高速铁路中五条现在正在建设中,第一条将于2009年竣工,第二条将于2010年.到2020年,中国高速铁路线将长12000公里,不过2
500亿美元的建设经费将会使所有这些项目都成为不确定工程,最终,将来的磁悬浮的系统在中国带来的前景不差于一般的基本线路.##的航线将成为第一项也是中国磁悬浮工程的最后一项,如果在中国批准建设##到广州的航线不超过44亿美元.
也许再没有哪一部分像轨道一样重要.轨道与车辆轮缘一起作用,使铁路运输体系与普通道路完全不同.
香辣带鱼虽然,现在钢轨是很普及的,但是在19世纪时,铁轨甚至木枕都是广泛使用的.很多早期的铁路是用薄铁条或铁皮条约束在木轨上给车轮提供一个光滑的跑道面.
钢轨的组成
钢轨是由铁、碳锰、硅,包括杂质如磷、硫、气体和炉渣组成的.这些物质含量的变化,可起到不同的作用,如增加曲线轨道的耐磨性.北美国钢轨的标志结构类似一倒T 型.T型轨的三要素是轨底、腹板和轨头.平底的钢轨能被直接地固定到木枕上；然后钢轨被放置到已设好的钢垫板上.19世纪中期以来,当钢轨的大小和标准的成型后接受长期的分析和精致时,基本的T型截面以成标准.
重量
最常见的描述钢轨的方法是用每码长的重量表示,它是钢轨横断面大小的函数.19世纪后期,钢轨被做成重量从40IBS每码到80IBS每码变化的一系列截面,重量的增加超过时间的变化,因此,目前钢轨以扎制成155-IB的截面,在第二次世界大战后的某个时间开始使用,是在美国用过的最重的钢轨.一般地,给定线路的运输吨位越大或速度越快,采用的钢轨就越重.由于轨道维修费用较高,越重的轨道寿命越长,从而越受欢迎,即使在载重轻运输慢的城市交通系统.重型钢轨常被用于道路交叉处,铁路转辄器及与其他线路的平交道口处.
钢轨的连接
在历史上,标准轨的长度是与运送它们的车辆长度有关系的.早期是从15英尺到20英尺变化的,钢轨的长度随车辆大小的增加直到39英尺的规格〔可被过去常用的40英尺长的车辆容易的容纳〕尽管现在有更长的车辆,但由于钢轨扎制机的限制和搬运的方便,钢轨的标准长度仍保持未39英尺.接头是钢轨的最薄弱点,会使行车不平稳,且维修费用高.个体的钢轨用叫做夹板的钢板连接,用4-6个螺栓夹在原位.现在,以过去只用于重型轨的六螺栓式接头为标准形式.接头螺栓是交替向内和向外布置的,以防止车辆车轮对钢轨的长期磨损后可能产生出轨,从而
动物粘土
使钢轨接头分离.两种不同型号的钢轨的连接是用特殊接头来实现的.用于信号服务的轨道,必须在接头处设有电线来形成闭和的电路.
钢轨的焊接
令人头痛的钢轨的连接问题激起显而易见的轨道模式的发展：无缝线路的采用.从20世纪40年代,最早在少数线路使用以来,在所有的应用X围内,无缝线路受到了欢迎.它是在工厂将39英尺〔或新的78英尺〕长的标准轨焊接成四分之一英里的长钢轨.
钢轨用特定的火车运送到需要地,当要卸下时,火车慢慢地从钢轨下开走.当就位以后,无缝线路通常是就地焊接成更长的轨道.许多接头轨道仍然保留是因为使用适度长的钢轨其寿命长,由于铺设无缝线路对设备特殊要求,使其短距离铺设是不经济的.红脸蛋怎么去除
对无缝线路由于湿度变化引起的膨胀和收缩的处理是很重要的.为了避免在使用中的钢轨的膨胀和自身的变形.无缝轨应在高温时〔或人为加热后〕铺设,钢轨用锚栓夹在轨枕上防止钢轨在温度降低时收缩而变短.这样约束后,钢轨仅在横向收缩.由于受拉,无缝轨在寒冷天气使用时应小心对接.
