The Iron Bridge across the River Severn, England

“Forming a perfect reflected circle in the waters of River below, this unique bridge assumes a grace that belies the fact that it is a heavy weight constructed from some 380 tons of iron.”

Magnificent and impeccable! That is how the first ever cast iron bridge gets described by every one who looks at this first engineering marvel. Built over the gorge of the River Severn in Shropshire, England, for centuries it carried only road traffic, but in 1934 it was restricted to pedestrians use. The Iron Bridge is one of the heritage sites declared by UNESCO.  Even though the Iron Bridge does not have the same practical purposes that it used to, it still remains a staple in English history. According to the official website, Iron Bridge leaves behind an incredible legacy of historical importance, the most significant of which was spurring on the Industrial Revolution.

The 60 meter span Iron Bridge designed by Architect Abraham Darby III, consumed 378 tons of iron and being the first of its kind, the construction methodology followed carpentry. Each member of the frame was cast separately, and joints followed the principle used in wooden joints such as the mortise and tenon and dovetail joints, adapted as necessary to the different properties of cast iron. Bolts were used to fasten the half-ribs together at the crown of the arch. Very large parts were needed tocreate a structure to span

Costing over £6,300, this proclamation of the achievements of Shropshire ironmasters was formally opened on New Year’s Day 1781. It continued in full use by ever-increasing traffic until closed and designated an Ancient Monument in 1934. Massive strengthening works were later undertaken, and in 1999-2000 English Heritage assisted with a full survey of this revolutionary and iconic structure.

The process of using coke made from local coal to smelt local iron ore was engineered at the beginning of the 18th century by Abraham Darby-1 and this technology was extensively used in the construction of the first ever built Iron Bridge across the river Severn in Shropshire, England. It was the first arch bridge in the world to be made of cast iron, a material which was previously too expensive to use for large structures. The iron bridge located at Iron Bridge Shropshire England is ranked as one of England's great 21 icons. This first iron bridge took four years to get completed between1 1777 to 1781.

The functional effect of this newly constructed cast-iron bridge was copious. The construction helped to achieve a more efficient means of transportation than the old ferry system that had previously existed. This new means of transportation allowed more access to the precious material that provides the majority of incentive for the design in the beginning.

Because no one had the experience of building this kind of a bridge using cast iron, Abraham Darby turned to carpentry practice for methods of joining the various components of the Iron Bridge. He employed mortice and tenon, and blind dovetail joints, reinforced with bolts and nuts.