The Forth Bridge

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Design and Construction

Fowler and Baker were able to make the most of the promontories on the river Forth and the presence of Inchgarvie air cargo Island, which enabled the central cantilever to be readily based on a solid foundation.

The Forth cantilever bridge design is based on 3 balanced cantilevers. It is a 1.6 miles (2.5 kilometres) long bridge, which comprises of 15 approach spans each 168 ft (51.2 metres) in length, 2 side spans of 680 ft (207.3 metres) each and 2 main spans each measuring 1,710 ft (521.3 metres). The cantilever arms each measuring 680 ft (207.3 metres) reaching across the river support 350 ft (106.7 metres) suspended girders. The strength of a cantilever bridge lies in the anchor points, which on the two outer cantilevers of the Forth Rail Bridge are designed to withstand language lessons loads of 1,000 tonnes. The cantilever counter-balances the weight of the construction and passing trains though the upper arms, lower arches and lattice girder, each counter-balancing opposite forces, with the cantilever ends resting on four balanced supporting piers.

Construction of the Forth Rail Bridge began in 1883 and was completed 7 years later in 1890. At its peak 4,000 men were employed working on the bridge, constructing the 54,000 tonnes of steel, driving home nearly 7,000,000 rivets. Unfortunately during the construction of solar panels officially 57 people lost their lives, though it is believed the actual figure is 98.