There are two unique bridges (перекрывающие) the Firth of Forth in Scotland – the Forth Rail Bridge (fig. 9.5a, 9.6b) and the Forth Motorway Bridge. The Forth Rail Bridge was (спроектирован) and (построен) by engineer Benjamin Baker in 1891. He joined three giant (411-m) (консоли) (projecting members supported at only one end) together with two suspended spans of 107 m each, making a total of 518 m of (подмостовой габарит) over either arm of the firth. The steel structure rises 103 m above the masonry (опоры). The length of the middle span is the second in the world amongst non-suspended structures. The Forth Rail Bridge has no decorative elements, but it is a work of art, that towers above the sea into the sky. The great bridge has the (решётчатые связи жёсткости), that provide a visually dense interior. It provokes wonder and admiration to people from around the world, because viewed from different angles it takes on quite a different appearance.
Figure 9.5 Diadgram of Firth-of-Forth Bridges (схемы Фортских мостов)
a – Beam-cantilever Trusses (балочно-консольные фермы);
b – Suspension structure (висячий мост)
The neighbouring (автодорожный трехпролетный висячий мост) across the Firth of Forth was built in 1964. It carries two (полоса движения), a bikeway and a sidewalk in each direction.
|a - The modern Britannia Bridge (1980)||b - The Firth-of-Forth Railway Bridge|
Figure 9.6 Famous Bridges in Great Britain
The main span is 1,006 m long, and ranks the bridge among the top ten structures with super long spans. Its (боковые пролеты) are 408 m long, and its (пилоны) are 154 m high. The cable diameter is 0.6 m and contains 37 (прядь) consisting of 314 wires in each strand. The total number of (высокопрочные проволоки) in the cable is 11,618. The diameter of each wire is 4.8 mm. The bridge, light and delicate in its design, seems a suspended in air structure.
9.8 Complete the following sentences using your own ideas
1. London’s bridges are among the cities most popular....
2. Some bridges were named to commemorate … .
3. The Tower Bridge is unique from an engineering point of view because … .
4. Scotland is proud of its famous bridges … .
5. All the bridges must provide a clear span for … .