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,Tower Bridge,Tower Bridge (built 18861894) is a combined bascule and suspension bridge in London, England which crosses the River Thames. It is close to the Tower of London, from which it takes its name, and has become an iconic symbol of London.,塔桥（内置18861894）是伦敦的一个组合式结构，悬索桥，英格兰横跨泰晤士河。它靠近伦敦塔而得名，并已成为伦敦的一个标志性的符号。,In the second half of the 19th century, increased commercial development in the East End of London led to a requirement for a new river crossing downstream of London Bridge. A traditional fixed bridge could not be built because it would cut off access by tall-masted ships to the port facilities in the Pool of London, between London Bridge and the Tower of London.,History,19世纪下半叶，随着伦敦经济的发展城市东部越来越紧要地需要一座横跨泰晤士河的桥梁。但这座桥不能是传统的桥，因为当时的码头位于伦敦桥和伦敦塔之间，假如新桥太低的话船就无法开到码头了。,A Special Bridge or Subway Committee was formed in 1877, chaired by Sir Albert Joseph Altman, to find a solution to the river crossing problem. It opened the design of the crossing to public competition. Over 50 designs were submitted, including one from civil engineer Sir Joseph Bazalgette. The evaluation of the designs was surrounded by controversy, and it was not until 1884 that a design submitted by Sir Horace Jones, the City Architect (who was also one of the judges),3 was approved.,1876年一个特别委员会成立来讨论这个过河问题的解决方案。它开始了一个方案设计竞赛，一共收到了50个不同的方案。但此后的讨论却拖延了许多时间和导致了很多激烈的辩论，最后这个委员会于1884年决定采用霍拉斯琼斯的方案。霍拉斯琼斯本人也是评审委员会的一员,Jones engineer, Sir John Wolfe Barry, devised the idea of a bascule bridge with two bridge towers built on piers. The central span was split into two equal bascules or leaves, which could be raised to allow river traffic to pass. The two side-spans were suspension bridges, with the suspension rods anchored both at the abutments and through rods contained within the bridges upper walkways,琼斯的设计是一座244米长的开启桥，桥有两个桥塔，每个塔高65米。桥的中部长61米，分为上下2层。上层高而窄，可作为人行道。下层是主通道，分为两扇桥段，每扇可以竖起到83度来让河流交通通过。这两扇桥段各重上千吨，它们的轴位于它们的重心上来减小它们起升时所需要的力，它们可以在一分钟内升起。一开始这个升降装置是液压的，为此它有六个水库来产生高压水。蒸汽机把水从水库泵入液压装置。今天桥是用电动机来升降的，但过去的蒸汽机机构依然保留可供参观,Construction started in 1887 and took eight years with five major contractors and employed 432 construction workers. E W Crutwell was the resident engineer for the construction.,Construction,1886年伦敦塔桥开建，建造共历时8年，5个主要建筑公司和共432建筑工人参与工程,Two massive piers, containing over 70,000 tons of concrete, were sunk into the riverbed to support the construction. Over 11,000 tons of steel provided the framework for the towers and walkways. This was then clad in Cornish granite and Portland stone, both to protect the underlying steelwork and to give the bridge a pleasing appearance,两座坚固的桥墩共使用了70,000吨水泥，桥塔和桥身共用了1.1万吨钢铁。桥塔和桥身的钢铁骨架外铺设花岗岩和波特兰石来保护骨架和增加美观,Now visitors can walk through in the tower bridge, not be charged. Visit the tower bridge from the north side of the bridge take the elevator up, watching the bridge for structural engineering, and then from the bridge at high channel across the Thames, river Thames and enjoy on both sides of the beautiful scenery,现在， 游人可在塔桥上步行浏览，不须收费。 参观塔桥可从北边的塔桥乘电梯上去，观看大桥的结构工程，然后从大桥的高空通道上走过泰晤士河，饱览泰晤士河及两岸的秀丽景色,
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