第四座桥是一个庆祝的苏格兰地标，以及铁路土木工程发展的里程碑。
It was the first major structure in Britain to be made of steel and its construction resulted in a continuous East Coast railway route from London to Aberdeen.
- 1850: the ‘train ferry’ was introduced between Granton and Burntisland. This service continued until the Forth Bridge was opened.
- 1873：8月5日，北方英国铁路获得初始权威，以建立围栏的悬浮桥。
- 1878: William Arrol begins construction of Thomas Bouch’s suspension bridge design.
- 1879: December, the collapse of Thomas Bouch’s Tay bridge in a storm immediately halts Forth Bridge construction.
- 1881: January, Thomas Bouch’s design for the suspension bridge across the Forth is abandoned.
- 1881: 11 June, the Forth Bridge Railway Company is jointly established by the North British railway, the Midland Railway, the North Eastern railway and the Great Northern Railway at a meeting at York.
- 1881: September, the cantilevered design for the Forth Bridge is accepted by Board of Trade.
- 1882: 3 July, the Forth Railway Bridge is approved by Act of Parliament.
- 1882：12月21日，建造这座桥的合同被授予格拉斯哥的Messers Arrol＆Co.。
- 1883: bridge construction begins.
- 1884: 26 May, the first caisson launched.
- 1885: 29 May, the last caisson launched.
- 1886: the foundations for the bridge are finished.
- 1889: November, the cantilever towers are completed. Testing of the bridge begins.
- 1890：3月4日，威尔士王子正式开放桥梁。本杰明贝克是斯特莱德的。
- 1913-1921：桥梁得到加强。
- 1923年: 1月1日,英国主线rai的分组lways into four companies takes place, although the Forth Bridge Railway technically remains independent until 1948.
- 1939年：10月16日，第四座桥正在第二次世界大战早早受到德国空军的袭击。
- 2001年: a major refurbishment of the Forth Bridge is announced.
- 2004: the Forth Bridge is commemorated on a £1 coin.
- 2007: the Forth Bridge is commemorated on the Bank of Scotland £20 note.
- 2011: the 10 year £130m project to refurbish the bridge is completed. The bridge will not need repainting for over 20 years.
The first crossing is begun
The first crossing of the Forth by the railway came in 1850 when the Edinburgh, Leith and Granton Railway started the world’s first ‘train ferry’ – a ferry boat specially designed by Thomas Bouch to take railway coaches – between Granton and Burntisland.
In August 1873 the North British Railway obtained authority to build a railway bridge across the Firth of Forth and construction of a suspension bridge, also designed by Thomas Bouch, began in 1878. However when Bouch’s original Tay Bridge collapsed during a storm in December 1879, work on his bridge across the Forth stopped immediately pending a full inquiry.
Bouch’s suspension bridge plans were abandoned in 1881 and designs for a new bridge were invited by the newly formed Forth Bridge Railway Company which had been established jointly by those railway companies who had most to gain from a railway crossing the Forth: the North British Railway, the Midland Railway and the North Eastern and Great Northern railways.
New plans are made
这座桥是在南队之间的跨越，现在是爱丁堡和北队的一部分，在南岸使用英寸加维岛。其设计必须符合规定第四次仍然是可通航渠道的海军部门的规格，以及最近的泰铢桥灾害的贸易委员会，他规定桥梁必须刚性和僵硬，能够携带最重的货运列车。
John Fowler and his partner Benjamin Baker were engaged by the Forth Bridge Company to develop their cantilevered design for the bridge which took into account these restrictions. The contract for its construction was let to Messers Arrol & Co of Glasgow in 1882 and work on the bridge started in 1883.
Bridge building on a vast scale
The Forth Bridge has three double cantilevers with two 1700ft suspended spans between them, at the time the longest bridge spans in the world. As required by the Admiralty, the rail level is 150ft (46m) above high water. Each of the towers has four steel tubes 12ft (3.7m) in diameter and reach to a height of 361ft (110m) above high water. Their foundations extend 89ft below this into the river bed, making the total height from foundations to the top of the towers 137 metres. The total length of the bridge, including its approach viaducts is 2,467 metres. The main structure itself measures 1,630 metres portal to portal.
Baker and Fowler’s bridge was the first major construction in Britain to be made from steel; the bridge incorporates 53,000 tonnes of the material.
The design of the bridge was very carefully balanced, with allowance being made for a maximum thermal expansion of 16½ inches (420mm) over the 5350ft (1630m) steel central structure. It incorporated 6.5 million rivets, which aggregated 4,200 tons weight alone. It was designed to withstand a wind force of 56lb per square foot.
Foundations and steelwork
Building the foundations for the vast towers started with the construction of huge caissons which were built on site and sunk using compressed air. The first of the caissons was floated into position on 26 May 1884.
By 1886 all the foundations were in position ready to take the steelwork. Thanks to the organisation and inventiveness of William Arrol, the bridge was completed in November 1889, just 6 years after work started (although at the time the weather was particularly cold and Arrol had to wait for milder weather conditions before the enormous structure expanded sufficiently for the final rivets to be inserted).
整体桥梁成本为300万英镑，建设4,600人的劳动力。
After all testing and inspections of the bridge were completed, it was formally opened by the Prince of Wales (later King Edward VII), who drove home a final gold plated rivet, on 4 March 1890. At the same ceremony, he also knighted Benjamin Baker.
Painting the Forth Bridge
2001年，宣布了第四座桥梁的重新翻新项目。在接下来的10年里，桥的部分被显着的脚手架接入系统覆盖，具有专门制备的筛选，以防止碎屑从喷砂和油漆影响或污染环境。
After removing the old paint back to the metal, any steelwork that required maintenance was repaired before the new paint was applied.
经过彻底清洁钢结构，然后在三个保护层中涂上涂料，两者都是无气喷雾的，并用手用手掌握，面积23万平方米。
翻新期间使用的技术和涂料意味着桥梁将不需要完整的油漆至少20年，最后将结束陷入“绘画第四桥”的神话是永无止境的任务。
Did you know?
所有由托马斯Bouch的悬架桥建造的一切都是单码头的英寸Garvie。今天它有一个小灯塔;被大规模的桥梁本身越过。