Iron Bridge, Shropshire
The Bridge was built in 1779 and took 3 months to complete this was because the parts of the bridge were already made in open sand moulds; this meant the pieces formed were either square or rectangle solid shapes. The processes used to build the bridge were more like carpentry e.g. woodworking joints; bolts were used to fasten the section together. The bridge is made in a semi circular design which enhances its natural surrounding in Iron Bridge Gorge. It is made up of 5 segments which go across the whole river; they are spaced so as not to disrupt the river traffic.
The main structure is curved semi-circular ribs cast in two pieces and pinned at the crown joint. Each rib consists of 3 arcs connected by radial castings the main span is 30 metres.
The bridge was made of more than 800 castings. The largest parts were 70 ft long and weighed 5.25 tons.
Regular repairs have had to be undertaken to the bridge mainly due to the movement of the river banks and the weight of the stone pillars which are forcing it into the river.
The bridge was closed in 1934 to traffic but is still used today as a footbridge.
Although the 100 foot bridge looks small compared to modern bridges it is probably the most famous of bridges as it is the first one made of cast iron.
The bridge’s foundations were strenthened in 1972 by arches put under the river. The bridge was again closed and renovated in 1999 and finished in 2002.
As there was no witnesses to how this bridge was actually built, the BBC did a documentary where a half sized model of the bridge was built. See the following link for information on this: