The Iron Bridge facts for kids

Quick facts for kids The Iron Bridge
The Iron Bridge (February 2019)
Coordinates	52°37′38″N 2°29′08″W / 52.62735°N 2.48550°W / 52.62735; -2.48550 (The Iron Bridge)
Carries	Pedestrian traffic
Crosses	River Severn
Locale	Ironbridge Gorge near Coalbrookdale
Owner	Telford and Wrekin Council
Characteristics
Design	cast-iron arch bridge
Longest span	100 ft 6 in (30.63 m)
History
Designer	Wilkinson
Constructed by	Abraham Darby III
Fabrication by	Abraham Darby III
Construction begin	November 1777
Construction end	July 1779
Opened	1 January 1781
Statistics
Toll	Free public access since 1950

The Iron Bridge is a famous bridge in Shropshire, England. It crosses the River Severn. This bridge opened in 1781. It was the first large bridge in the world made from cast iron. Its success showed that cast iron could be used for building. Today, it is a symbol of the Industrial Revolution. This was a time when new machines and factories changed how things were made.

The Ironbridge Gorge is a deep valley. It was formed by melting ice after the last ice age. This area had many useful materials like coal and iron ore. These were easy to dig up. But the deep gorge made it hard to build a bridge across the river. Thomas Farnolls Pritchard suggested building a single iron bridge. This would help with the unstable riverbanks. It would also keep the river clear for boats.

Building the bridge took two years. Abraham Darby III was in charge of the ironwork. The bridge spans 100 ft 6 in (30.63 m) across the gorge. This height allowed tall boats to pass underneath. In 1934, the bridge became a scheduled monument. It was then closed to cars. People had to pay a small fee to walk across until 1950. That is when the public took over the bridge.

For many years, the bridge was in poor condition. But in the late 1900s, it was carefully repaired. The bridge, the nearby town of Ironbridge, and the gorge are now a UNESCO World Heritage Site. This means they are very important to the world's history.

History of the Iron Bridge

Why a Bridge Was Needed

The Ironbridge Gorge was created by melting ice after the last ice age. This natural event exposed valuable resources. These included coal, iron ore, and limestone. These materials were easy to mine from the ground. The River Severn was a key way to transport goods. This made the area important for the growing Industrial Revolution.

In 1709, Abraham Darby I used local coal to make iron. This process used a fuel called coke. Soon, Shropshire became a major industrial area. This was because local mines offered cheap fuel. The River Severn was great for trade. But it also made it hard to cross the deep Ironbridge Gorge. The closest bridge was 2 miles (3.2 km) away.

People wanted a bridge to connect the industrial towns. These included Broseley and Madeley. The bridge also needed to be high enough for boats. It also had to be a single span. This was due to the river traffic and steep banks. The unstable riverbanks made building a bridge very difficult.

The Iron Bridge was the first of its kind. But it was not the first iron bridge ever thought of. An iron bridge was started in France in 1755. But it was too expensive to finish. A smaller iron footbridge was built in Yorkshire in 1769.

How the Idea Began

In 1773, an architect named Thomas Farnolls Pritchard had an idea. He wrote to his friend, John Wilkinson. Wilkinson was an iron expert. Pritchard suggested building a bridge from cast iron. Pritchard had designed wooden and stone bridges before.

In 1773–74, local newspapers asked for support. They wanted to build a single iron bridge. It would span 120 feet (37 m). By 1775, people had raised money for the project. They collected between £3,000 and £4,000. Abraham Darby III was chosen to manage the money. He was Abraham Darby I's grandson.

In March 1776, a law was passed to build the bridge. Abraham Darby III was hired to make and build the bridge. But in May 1776, the project leaders changed their minds. They asked for plans for a bridge made of "stone, brick or timber." No good plans came in. So, they decided to go with Pritchard's iron design. But they set strict rules for cost and time. In July 1777, the bridge's span was changed. It was set at 100 feet 6 inches (30.63 m). This was likely to make space for a towpath.

Building the Iron Bridge

Building the Bridge

A painting of the bridge being built in 1779. It was painted by Elias Martin.

A model showing how the Iron Bridge was put together. This is at Blists Hill Victorian Town.

The bridge was built where a ferry used to cross the river. This spot was chosen because both sides were high. The ground was also very solid. The law said the bridge would connect two specific points. Pritchard died in December 1777. This was only a month after work began. He had been sick for over a year.

The bridge has five main cast iron ribs. These ribs create a span of 100 feet 6 inches (30.63 m). The bridge used 378 long tons 10 cwt (847,800 lb or 384.6 t) of iron. It has almost 1,700 separate parts. The heaviest part weighs 5 long tons 5 cwt (11,800 lb or 5.3 t). Each part was cast to fit perfectly. They were not standard sizes. Some "identical" parts were different by several centimeters.

The stone foundations were built between 1777 and 1778. The iron ribs were put in place in the summer of 1779. The bridge first connected the riverbanks on July 2, 1779. It opened for people to use on January 1, 1781.

In 1997, a painting was found in a museum in Stockholm. It was by Elias Martin. It showed the bridge being built in 1779. The painting shows a wooden scaffold in the river. This scaffold was used as a crane. It lifted the iron ribs into place. The ribs came by boat from Darby's factory. In 2001, a half-size model of the bridge was built. This was for a TV show called Timewatch. It showed how the bridge was assembled.

Bridge Design

Structural detail showing the five cast-iron ribs of the bridge.

The bridge has decorative rings and shapes. These are between the main ribs. They suggest that Pritchard designed the final look. Similar designs are seen in a gazebo he rebuilt. A foreman named Thomas Gregory drew the detailed plans. He used woodworking joints. These included mortise and tenon and dovetail joints.

The two outer ribs have words carved into them. They say: "This bridge was cast at Coalbrook-Dale and erected in the year MDCCLXXIX." This means 1779 in Roman numerals.

Two extra iron arches support a towpath on the south side. They also help during floods. A stone arch with a brick vault is on the north side. This carries a small path.

What the Bridge is Made Of

The Iron Bridge is made of cast iron. This material is very strong when pushed. But it is not as good as steel or wrought iron when pulled or bent. This is because cast iron is brittle. It can break more easily.

Scientists studied a piece of the arch and a strut from the bridge. They found these elements:

A small amount of sulphur in cast iron is okay. But too much can be a problem. However, enough manganese helps make the sulphur harmless.

Puddled wrought iron was a better building material. But it was not widely available until after 1800. It became the top choice for bridges and other structures. Then, new ways to make steel were invented. These included the Bessemer process in the late 1800s.

How Much It Cost

Darby agreed to build the bridge for £3,250. This money was raised by people who supported the project. Most of them were from Broseley. The actual cost of the bridge is not fully known. But old records suggest it was as high as £6,000. Darby was already in debt. So, he agreed to pay the extra cost.

However, by the mid-1790s, the bridge was making a lot of money. The fees collected from tolls gave investors an 8 percent profit each year.

Later History of the Bridge

An aerial view of the Iron Bridge in 2008.

The bridge's opening changed the area. Roads around the bridge were improved. The town of Ironbridge grew at the north end. It was named after the bridge. The bridge's owners and local businesses promoted the bridge. They wanted important people to visit it.

Bridge Repairs Over Time

In July 1783, a wall was built. It was 35-yard (32 m) long. This wall stopped the north bank from sliding into the river. In December 1784, cracks appeared in the stone arch on the south side. The nearby support also showed signs of moving. The gorge often has landslides. More than 20 have been recorded there. People thought the gorge sides were moving inward. This pushed the bridge's feet together. So, repairs were done in 1784, 1791, and 1792.

In February 1795, a big flood hit the River Severn. All other bridges nearby were destroyed. But the Iron Bridge survived. Its strong, open design let the floodwaters pass through. The medieval bridge at Buildwas was replaced. Thomas Telford designed a new cast iron bridge for it. His design used half the iron of the Iron Bridge. This was even though it had a longer span of 128 feet (39 m). The Buildwas Bridge lasted until 1906.

In 1800, the bridge owners ordered more repairs. These lasted several years. The stone arches were replaced with wooden ones. This helped reduce pressure on the main span. It was too hard to build a rigid support at that time. But this was done during later repairs in the 1970s. In 1812, Charles Hutton said the bridge's construction was "very bad." He thought it would not last long. But he said this was due to cracks in the stone, not the iron. The wooden arches were replaced with cast iron ones in 1820. More repairs were needed throughout the 1800s.

Around 1870, an engineer named Sir B. Baker said the bridge needed fixing for 90 years. This was because the main arch and side arches did not work well together. They broke due to expanding and shrinking. When they broke, they were patched up. Then bolts broke, or the iron broke somewhere else. He said it was still strong and safe. He advised fixing the broken ribs. He also suggested using oval holes for bolts. This would allow for movement.

On August 24, 1902, 30-foot (9.1 m) of the side railing fell into the river. In July 1903, a piece of the bridge deck fell off. It weighed about 5 long hundredweight (250 kg). A new concrete bridge opened in 1909. It did not charge tolls. This worried the Iron Bridge owners. But the Iron Bridge was still used by cars and people.

Closing to Cars

The Iron Bridge Tollhouse.

An old sign showing the bridge tolls.

People walking on the bridge in 2019.

In 1923, engineers said the main part of the bridge was fine. But they thought the metal deck was too heavy. They suggested removing some weight. Then, the bridge could reopen to vehicles. But cars could be no heavier than 2 tons. They also had to stay in the middle of the road. A weight limit of 4 tons was set. But in the 1930s, many new houses were built. Drivers delivering tiles wanted to use the bridge. So, the owners decided to close it to cars. This happened on June 18, 1934.

People still paid to walk across until 1950. Then, Shropshire County Council took over the bridge. The money from tolls barely covered collection costs. There was no money for repairs. The bridge had not been cleaned or painted in years. Because it was in bad shape, some people suggested tearing it down. Others wanted to move it. In 1956, the County Council wanted to demolish it. But this plan did not happen. The Ironbridge Gorge Museum Trust was formed in 1967. Its goal was to protect the area's history. They got money from the council for repairs.

Restoring the Bridge

Renovations to The Iron Bridge

The Iron Bridge being repaired in 1974.

The Iron Bridge being repainted in 1980.

Repairs to the bridge's foundations began in 1972. They cost £147,000. This money came from the County Council and other groups. Engineers decided to put a concrete arch under the river. This would stop the bridge supports from moving inward. The work started in spring 1973. But high summer floods stopped the work. They washed over the temporary dam.

Material was removed from the south support. This made it lighter. The arch through it was strengthened with concrete. The road surface was replaced with lighter tarmac. The stone supports were repaired. The toll-house was made into an information center. In 1980, the bridge was painted for the first time in the 1900s. The work was finished for the bridge's 200th birthday. This was celebrated on January 1, 1981.

Before and After Restoration

     The bridge was blue-grey before restoration (2014).

     The bridge is now red-brown since restoration (2019).

Between 1999 and 2000, the bridge was covered in scaffolding. This allowed English Heritage to examine it. The bridge was also repainted. Small repairs were done. In January 2017, English Heritage announced a new project. It was a £1.2 million restoration of the Iron Bridge. This started in September 2017. It was their "biggest ever conservation project." The cost was later quoted at £3.6 million. English Heritage said it was a big effort. It would fix the ribs, arches, stonework, and deck.

Surveys showed the bridge was in danger. This was due to stress from its original build. Ground movement over centuries also caused problems. An earthquake in the 1800s also played a part. Besides structural repairs, the bridge changed color. It went from blue-grey to its original red-brown. Scientists found this was its first color.

Damage Before Restoration

A cracked joint on the bridge (2003).

Broken supports on the bridge (2004).

The project received some funding from crowdfunding. People raised £47,545. A German group, the Hermann Reemtsma Foundation, gave €1,000,000. This was their first time funding a project in the UK. After the work, the bridge reopened on December 6, 2018.

Awards and Recognition

The bridge, the town of Ironbridge, and the gorge are a UNESCO World Heritage Site. This was created in 1986. The bridge is a Grade I listed building. This means it is very important. Telford and Wrekin Council owns it.

In 1934, it became a Scheduled Ancient Monument. In 1979, the American Society of Civil Engineers recognized it. They called it an International Civil Engineering Landmark.

In 2020, the bridge's restoration work won an award. It was honored in the European Heritage Awards. These awards celebrate great heritage projects in Europe.

How the Bridge Changed Design

The Iron Bridge was the first major bridge made of metal. It greatly influenced new ideas in building and technology. Its success led to many other bridges being built with cast iron. Large cast iron arches were built in the late 1700s and early 1800s.

• In 1786, Thomas Paine showed models of iron bridges. He promoted them in Paris and England. He built a 90-foot iron rib. It weighed three tons. Later, he built a full bridge with five ribs. It was 210 feet long. It was put up in a field for display.
• From 1793 to 1796, the Wearmouth Bridge was built. It had a span of 235 feet (72 m). It was made of cast iron parts. These parts were like the stones in a masonry bridge. This bridge used some iron from Paine's earlier bridge.
• In 1795, a big flood on the River Severn destroyed all nearby bridges. Only the Iron Bridge survived. Its open design let the water flow through. Thomas Telford was a public works surveyor in Shropshire. His design for the new bridge at Buildwas was like the Iron Bridge. But it was 30 feet (9.1 m) wider. It also used less than half the iron. Telford went on to design many cast iron bridges. The oldest one still standing is the Craigellachie Bridge.
• In 1799, the Coalport Bridge was rebuilt after the flood. It had one span and three cast iron ribs. This version was updated in 1818. Two more ribs were added. It is still standing today.

The Bridge in Art

William Williams' 1780 painting shows the bridge's original red-brown color. Abraham Darby III asked him to paint it.

More than 50 artists came to the Coalbrookdale area. They visited between 1750 and 1830. They wanted to see and draw the rise of industry. They also wanted to capture the changing landscape. One of the first artists to paint the bridge was William Williams. He was paid 10 guineas in October 1780. This was for a drawing of the bridge.

An engraving by Michael Angelo Rooker became very popular. Thomas Jefferson bought a copy. He displayed it in his dining room at Monticello.

In 1979, the Royal Academy of Arts held an exhibition. It was called "A View from the Iron Bridge." This celebrated the bridge's 200th birthday.

See also

In Spanish: Iron Bridge para niños

• List of crossings of the River Severn
• Listed buildings in The Gorge