The Iron Bridge,(Ironbridge Gorge, UK); 1775-9; Industrial Revolution

The Iron Bridge is a bridge across the River Severn in Shropshire, England. It is opened in 1781. It was the world's first bridge made of cast iron and to make this material become popular after construction due to the use of new materials in next century.It also showed the great result of Industrial Revolution after 1760. 

Even though the time is in the Industrial Revolution, but it still in the beginning .Construction technique ,mining skill, and smelting skill were not maturity. 

The site is close to the ferry between Madeley and Benthall, because it is close to both sides and the ground is relatively strong. The Parliamentary Act describes how to build a bridge near Samuel Barnett from a point of view of the Benthal Parish, near a place on the other side of the Tomask-Rupton house.

Masonry and abutments were built between 1777 and 1778. In the summer of 1779 the ribs were lifted into place by the use of wooden jibs and cranes. The bridge first crossed the river on July 2, 1779, January 1, 1781.

Unusually, the bridge is still incomplete: it lacks its two lower arches on the town side. These parts were cast and added a lot, but they were cast as hollow rather than solid, because the rest of the bridge, pointing out that their completion work is more aesthetic than necessary exercise.

This bridge is a carpentry design, usually used for wood construction, consisting of five sections of cast iron ribs spanning 100 feet 6 inches (30.63 meters). During the construction of this bridge, 10 tons (847,800 pounds or 384.6 tons) of iron were used, up to 378 tons, and the heaviest was nearly 1,700 individual components weighing 5.5 tons (5.6 tons). Instead of a standard size, the difference between "same" components in different locations can reach several centimeters.

The decorative ring and ogees between the ribs of the bridge structure showed that the final design was Pritchard’s because the same element appeared in the pavilion he had rebuilt. The foreman of the foundry Thomas Gregory drew a detailed pattern for the members, using woodworking to pick up details such as blinking and smashing joints and dovetails.

The iron bridge is made of cast iron. Compared to steel and wrought iron, it is not a good structural material for handling tension or bending moments due to its brittleness and low tensile strength. In a few cases, bridges and buildings built with cast iron have failed. Cast iron has good compressive strength and was successfully used in well-designed old bridges and certain structural components in buildings. The cement iron introduced after the completion of the iron bridge is a better structural material. After 1800, cement iron was widely used. It was not until the late 19th century that a new steel making process was developed and eventually became the material of choice for bridges, rails, ships and buildings.