The Iron Bridge
The Iron Bridge is the world's first cast iron arch bridge . It has spanned the Severn since 1779 at Ironbridge, south of Coalbrookdale in Shropshire , England, named after the bridge . It was therefore originally (and occasionally still) called Coalbrookdale Bridge . Originally called Severn Gorge , the gorge was named Ironbridge Gorge . The Ironbridge Gorge, together with the bridge and the industrial settlements of the town of Ironbridge, has been on the UNESCO World Heritage List since 1986 .
The bridge consists of an arch with a span of 30.62 meters and an arch height of 12.8 meters. Each of its five girders, 1.49 meters from center to center, is made up of three concentric arches connected by radial rungs using bolts. The inner one consists only of two pieces joined together at the apex of the arch. In the spandrels there are cast iron rings that were used as essential load-bearing elements in later bridges. The arches rest on 40 centimeter thick cast-iron panels supported by masonry, which also accommodate vertical supports connected by cross bars, through which the two outer arches go and are stiffened at the same time. The roadway resting on these supports and arches consisted of cast iron plates, over which a top layer of clay and coal slag was spread.
The bridge essentially consists of 482 cast parts, if you add the cladding and railings, there are a total of 1736 cast parts.
Until the bridge was built, ferries were the only way to cross the Severn Gorge, but the iron industry grew strongly in the 18th century and required a more reliable and faster route. The idea of an iron bridge was probably developed from 1773. The idea probably goes back to the local iron producer John Wilkinson in collaboration with the architect Thomas Farnoll Pritchard . Pritchard created various designs for the bridge in 1775. Abraham Darby III was responsible for the final design and execution, but could also have helped develop the idea. Construction took only three months and was completed in the summer of 1779. According to other sources, construction began as early as 1777, but this could also mean the beginning of the production of the castings.
Since there was no previous experience of building bridges with iron, methods from the carpentry trade were used. The exact events from the year of construction in 1779 are not known. The first of two arches spanned the River Severn on July 2, 1779. The access roads then had to be built. The bridge was opened on New Year's Day 1781.
Just a few years after completion, movements in the foundation caused cracks in the iron and in 1802 the stone southern pillar had to be replaced by a temporary wooden structure, in the place of which an iron arch was finally inserted.
The last major work on the foundation took place in 1972, after road traffic over the bridge had ceased in 1934 and pedestrians had to pay tolls until 1950. The bridge has been owned by Shropshire County Council since 1950.
In November 2017, the Hermann Reemtsma Foundation in Hamburg provided one million euros to save the Iron Bridge in Shropshire.
Today a number of museums can be found in the valley of the Severn, which have the theme of the age of early industrialization . These include a furnace for iron from the 18th century, the Blist Hill Open Air Museum with exhibitions on the Victorian era, the Coalport China Museum ( porcelain ), the Rose Hill House (museum about the daily life of the 18th century) and a workshop for the production of bricks . The Iron Bridge over the Severn and the museum network are anchor points of the European Route of Industrial Culture (ERIH).
- UNESCO World Heritage Center: Ironbridge Gorge
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