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The Cornwall Railway company constructed a railway line between Plymouth and Truro, England, opening in 1859, and extended it to Falmouth in 1863. The topography of Cornwall is such that the route, which is generally east-west, cuts across numerous deep river valleys that generally run north-south. At the time of construction of the line, money was in short supply due to the collapse in confidence following the railway mania, and the company sought ways of reducing expenditure. On the advice of the Victorian railway engineer Isambard Kingdom Brunel, they constructed the river crossings in the form of wooden viaducts, 42 in total, consisting of timber deck spans supported by fans of timber bracing built on masonry piers. This unusual method of construction substantially reduced the first cost of construction compared to an all-masonry structure, but at the cost of more expensive maintenance. Replacement of the timber viaducts by all-masonry structures began in the 1870s but a few remained in service until the 1930s. ==History== The Cornwall Railway linked Plymouth with Falmouth. The section from Plymouth to was opened on 4 May 1859, and the remainder to Falmouth on 24 August 1863. Although the line had been designed by Brunel, this was after his death and the construction under the supervision of R P Brereton. It was built as a single-track broad gauge line. The of railway crossed 45 rivers and deep valleys. Of these 43 were spanned by viaducts of various types built partly or entirely from timber. Workshops were established at where timber could arrive on barges to be preserved and cut to size. The offcuts from the timbers used for the viaducts and track were then used for the construction of the railway's buildings. The choice of timber was made to keep initial costs down, but Brunel had warned that this meant more expensive maintenance—running to £10,000 annually. Replacement of the viaducts started in 1875 but led to a dispute in 1884 between the Cornwall Railway and the Great Western Railway which was leasing the line. The lease precluded the conversion of the line to standard gauge, and the Cornwall Railway refused to pay for the widening of the viaducts during rebuilding sufficient to accommodate a double line of standard gauge tracks. Following the amalgamation of the two companies on 1 July 1889 all the remaining viaducts on the main line to Truro were replaced. Most were either rebuilt in situ or by a replacement viaduct built immediately alongside, and in the latter case many of the original piers still remain today. Between Saltash and St Germans, a deviation line was built in 1908, eliminating the wooden viaducts on by-passed section of line. Those on the Falmouth branch were all replaced between 1923 and 1934.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cornwall Railway viaducts」の詳細全文を読む スポンサード リンク
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