History of bridges could not be told properly without an extensive look back to the 18th century western England, in the area of Severn Gorge where one bridge managed to change our approach to bridge making. After that region became the local center of iron smelting industry, proposals were made, and a magnificent 100 feet bridge created from a single cast iron arch was made across Severn Gorge. Suitably, the bridge was named Iron Bridge, and it represented the first major bridge in the world that was made out of cast iron. This made it unique, and a strong proof for the creation of many other bridges made out of this for that time unique construction material.
Built between November 1777 and July of 1779 over the River Severn in Shropshire, England, the bridge was finally opened to the public on 1 January 1781. After which it served as an important transport point between industrial town of Broseley and the neighboring smaller mining town of Madeley, and the rest of the industrial points of Coalbrookdale region. Up to that point, the transport of iron and coal was possible only via river routes and long and twisty roads that caused many delays in delivering of goods. Because of the presence of impressive gorge, proposals for the bridge noted that the bride should be made with a single strong arc, which would allow not only spanning 30+ meters of air between steep banks of the gorge, but also allow tall ships to pass underneath it. After several years of pre-production efforts, the full construction of the bridge started in late 1777. The effort of designing and building the bridge was overseen by Abraham Darby III (grandson of the first Abraham Darby, famous English ironmaster) and famous architect and interior decorator Thomas Farnolls Pritchard.
Before the creation of Iron Bridge, only smaller structures made from cast iron were created – partially made and abandoned bridge in Lyon in 1755, and a small iron footbridge in Yorkshire in 1769.
The location where Iron Bridge was constructed formed an important transport point in the Shropshire region, which promptly caused the creation of first buildings, and quickly after that formation of the Ironbridge village. Today, this village is a part of the civil parish of The Gorge, in the borough of Telford and Wrekin. Since it is located in the heart of Ironbridge Gorge, and directly around both banks of the Iron Bridge, the early decades of the history of the village were fully dedicated on supporting the local industry of coal and iron mining and processing. The village was promoted to the tourists as the " Birthplace of the Industrial Revolution," and a location where people from all around England could come and see the revolutionary process of cheaply smelting iron with coke. Of course, modern historians today agree that the process of the industrial revolution within England did not start in the region immediately around Ironbridge village, but across many locations and with influences of many inventors and entrepreneurs.
The largest industrial point near Iron Bridge was without any doubt Darby's iron smelting facility, which helped to streamline the process of iron smelting before it was superseded by the more cost-efficient output of other regions of England. Even though the area around Iron Bridge did not play such an important part in the history of English iron production, the mere existence of the impressive cast-iron bridge, a first who was made from such heavy construction material, is today regarded as an important piece of history.
Immediately after the bridge was built and opened in 1781, this region started attracting more and more attention. People from the dispersed settlement of Madeley Wood were relocated to the Iron Bridge, and with them came the ancient Madeley market, construction of the new village square, new hotel that was intended to be used by tourists and travelers, and several buildings connected with the new commercial and administrative center of the Coalbrookdale. The hillside above the river featured 16th century stone lodge at Lincoln Hill, and numerous workers cottages and a large number of Georgian houses built by wealthy ironmasters, mine owners, business families, and even several villas created by the wealthy Victorian-era elite. By the 19th century, the village grew and gained several more notable buildings, of which most important one was St Luke's Church. It was finished in 1837 with design decorations by Samuel Smith of Madeley and glasswork of David Evans of Shrewsbury. During the 19th century and more than half of 20th, south side of Ironbridge village was home to the former Iron Bridge and Broseley railway station that operated on the Severn Valley line (GWR) from Hartlebury to Shrewsbury.
By the mid-20th century, Iron Bridge and the area immediately around it became part of a UNESCO World Heritage Site, making it a large tourist attraction. Today, most of the village is focused on tourism, with many festivals being centered around the bridge. The most popular annual event of the village is annual Coracle Regatta is held in August on the River Sever.
Broseley is a small town in Shropshire, England, located at the south bank of the Ironbridge Gorge, near the River Severn and the location where Abraham Darby III and Thomas Farnolls Pritchard erected the famous Iron Bridge and essentially created an Ironbridge village around it. The town of Broseley plays an important part in the history of Iron Bridge. The area around the town was quite famous for mining of stone, metal and other ore, and ironmasters of that region became very interested in building better roads to the rest of the regions of England. The industry was so strong in this region, that town of Broseley still holds the claim on the oldest railway ever produced in England.
The town was also important for developments in iron ore processing. Ironmaster Abraham Darby I developed his influential process of smelting iron using coking coal in this area (thus fueling the rise of the Industrial Revolution), and was buried there after his death in 1717. Additionally, Broseley was also a place where English industrialist John Wilkinson built the first boat in the world out of iron.
With such strong industry, it is not strange that ironmasters of Broseley and other towns in the region demanded better access points and roads to transport their goods to the rest of England. Abraham Darby III started planning for the creation of the Iron Bridge while living in Broseley, and much of its construction was overseen from this location. After the bridge was built, the town continued to thrive, but in the latter half of 19th century, the large industrial presence stated to lessen, and the entire area around the town entered into a financial decline, leaving behind numerous abandoned mines, buildings, pit mounts, and quarries.
The town of Broseley and the entire region bounced back from the harsh financial situation only in the second half of 20th century, after the town of Telford was established nearby across the River Severn. This fast-growing city pushed the region into rebuilding, many new homes were built, businesses moved in, pushing the town’s population to almost 5 thousand (almost to the level it had during the height of industrial revolution two centuries ago).
Iron Bridge also had a big impact on the development of the town of Madeley, Shropshire, which is today only a part of the newly developed city of Telford. Established in sometimes before the 8th century, Madeley was initially set as a market town until the 14th century when coal was discovered in 1322, and ironstone extraction began in 1540. During the following decades. The town becomes more and more invested in facilitating trade and mining, which was greatly boosted with the building of the famous Iron Bridge on the nearby Iron Gorge and the River Sever. This bridge connected Madeley with Coalbrookdale, enabling not only faster travel times but also a quick boost to the growth of the newly developed Ironbridge village.
Today, Madeley parish is home to almost 18 thousand people, and a significant part of the Iron Gorge is protected by being accepted as UNESCO World Heritage Site.
The Severn Gorge (later called Ironbridge Gorge) is among the most impressive natural formations in Shropshire, which is a part of the large county West Midlands, England. This large and deep gorge that holds the River Severn has been formed by glacial overflow from the ice contained in the distant lake Lapworth at the end of the last Ice Age that ended approximately 12 thousand years ago. The entire gorge structure was formed when the originally north-flowing river become trapped at the Lake Lapworth the Ice sheet from the Irish Sea dammed the river. Ensuing rise of water levels produced the new flow of the river toward the south, which eroded the hills and created a deep gorge that permanently rerouted River Severn even when the ice melted off.
The natural drilling that ice managed to do has helped settlers of this region to gain easy access to vast deposits of limestone, coal, iron ore and fireclay, which enabled this region to exhibit sharp economic development during the early years of industrial revolution.
Iron Bridge, Iron Gorge and nearby Ironbridge settlement are protected by UNESCO as a World Heritage Site.
Many towns were formed immediately around the Severn gorge, and with the development of new iron processing capabilities, local entrepreneurs devised a plan to build a bridge that would not only span the full distance of the gorge (some 30 meters) but also leave enough space below the bridge for uninterrupted shipping on the River Severn below. The river transport business was very important at that time since River Severn enabled local businesses to easily ship their products all the way to the Bristol Channel and the sea. This forced the designers and builders of the bridge not to use wood or stone (the only available bridge materials of the 1st half of 18th century), but to take a risk and create first ever large bridge created only from cast iron. The finished Iron Bridge in 1781 that connected the mining town of Madeley to larger industrial town of Broseley managed to transform the region, becoming not only the backbone of the land transport but also serving as a marvel of innovation and a monument of the iron industry that was developed all around the Severn Gorge. The bridge was used to transport a wide variety of raw materials and finished products to the industrial centers of Coalbrookdale all thought the end of the Industrial Revolution, after which many industries started slowly moving away from this region of England. The fame and impact of the bridge became so great, that the Severn Gorge very quickly became called as the Ironbridge Gorge.
Today, much of the Ironbridge Gorge (around 260 hectares) is protected as the World Heritage Site. This includes the location of the famous Iron Bridge that is located in the center of the Ironbridge village.
Since the discovery of rich reserves of coal, limestone, and iron ore in the Shropshire, entrepreneurs from this region started devising a plan for transporting their raw materials or finished goods to other parts of England. One of the biggest issues in this region was the presence of the deep Severn Gorge, whose steep sides and high walls prevented not only transport from one side of the gorge to another but also created a unique problem when building a bridge. Because River Severn was used extensively to transport goods from Shropshire to the Bristol Channel, any bridge that strived to span an entire gorge had to have a single large arc that would not interfere with the shipping on the river below.
After the local ironmaster Abraham Darby I managed to smelt local iron ore from coke in 1709, the entire region of Shropshire was transformed into an industrial center over the period of just a few decades. The increase of mining, manufacturing and heavy transport caused locals to acknowledge that Severn Gorge will have to be spanned with a large bridge since traveling around the gorge has proven to be wasteful in both time and money. The greatest need for a bridge was in the region between the larger industrial city of Broseley and a smaller mining town of Madeley, who were separated by the gorge and with the closest bridge being two miles away.
Building a large bridge between towns of Broseley and Madeley was not an easy task. Gorge was not only wide between those two industrial settlements, but the banks were also unstable and very steep which introduced an additional complexity to all phases of the building the bridge – from the very concept, creation of proposal, finalization of plans (which changed several times) and the actual construction.
The design phase started in 1773, with the combined effort of the bridge architect Thomas Farnolls Pritchard and the local ironmaster John Wilkinson of Broseley. They devised a plan for a120 feet bridge made only from cast iron but lacked the funds to accomplish that feat. The money was asked from the government via petitions to the Parliament in 1773-1774. They were finally awarded a subscription of between 3 and 4 thousand pounds in 1774, and the position of the official treasurer of the project was awarded to Abraham Darby III, an ironmaster from Coalbrookdale and the grandson of Abraham Darby I.
The design plans for the bridge were presented to the House of Commons in March of 1776, where they received a Royal Assent. This gave permission to Abraham Darby III to start funding construction of the bridge. However, Darby’s commission was withdrawn in the May of the same year, demanding to switch from the cast iron to the bridge made out of more traditional materials such as stone, brick or timber. Cast iron is famous for being brittle and not managing to handle high bending moments and tension. Doubters of this project openly promoted that several other structures (such as homes or warehouses) were destroyed because cast iron was obviously inferior to materials such as steel or wrought iron. However, since no alternative designs were presented, the original plan of Darby III was re-affirmed even though many had doubts about the viability of the cast iron as a material for bridge-building. The scope of the bridge was reduced during those months from the original span of 120 feet to 90 feet and then increased to 100 feet 6 inches (30.63 meters) which was the final length of the bridge.
The construction of the Iron Bridge started in November 1777, just one month before the death of bridge architect Thomas Farnolls Pritchard due to the long illness. The site of the bridge was located just adjacent to the place where ferry carried people and goods between Madeley and Benthall. This place was well suited for the bridge because of the high approaches on both sides of the Severn Gorge and isolation of the place which allowed for the creation of large construction site. The plans adopted by the Act of Parliament clearly stated how the bridge was to be built between Benthall parish near the house of Samuel Barnett and an opposite shore near the house of Thomas Crumpton.
Banks of the shore were reinforced with the masonry and abutment construction during 1777 and 1778, and the ribs of the bridge were lifted by cranes and wooden derricks and placed into the place during the summer of 1779. Even when the bridge spanned over the river, it was not fully completed. The construction demanded that fully-casted steel is used for the upper pars of the bridge, while lower arch sections on the side of the town were added later. Those sections were hollow and much lighter and were done not to provide additional support or carry capacity to the bridge, but to make it more visually appealing.
Iron Bridge carried the road across the River Severn for the first time on 2 July 1779 and was released for public use on 1 January 1781.
The cost of the bridge was originally capped at a maximum of around 4 thousand pounds which were collected from the people and contributors from the region (mostly from Broseley). However, reports say that Abraham Darby III provided additional funds even though he lacked funds due to other commitments and debts. In the end, the bridge cost went up to 6 thousand pounds, which in today’s money would translate to 0.9 million pounds or 1.3 million dollars.
The core design of the bridge was derived from the basic design of the wooden bridge, with five cast iron ribs that form the span of 100 feet and 6 inches. The components of the bridge were not “standardized” to enable easier implementation on site or use on other bridge construction sites. Instead,each component of the bridge (over 1700 of them) was cast individually to fit each other, and many of them had manufacturing discrepancies that resulted in mistakes up to several centimeters. The heaviest components ended up weighing 5.5 long tons (5.6 tons), and the total weight of the bridge ended being 378 long tons (384.6 tons).
Decorations based on previous designs of Thomas Farnolls Pritchard were placed on rings and ogees, but since he died immediately after early construction started, the majority of the decorations were added by other members of the construction crew. Majority of notable decorations were commissioned by the Thomas Gregory, foreman at the foundry where pieces of the bridge were cast. He included details such as dovetails, mortise, and tenon joints.
Cast iron is famous for having good compressive strength, but it lacks in the areas such as handling tension, tensile strength, bending moments and it is quite brittle . However, even with these disadvantages, cast iron was a material of choice in the building of numerous bridges all around the world, and especially during the decades of Industrial Revolution.
After Iron Bridge that spanned Severn Gorge, cast iron was used by Thomas Telford in the creation of bridge at Buildwas and London-on-Tern Aqueduct on the Shrewsbury Canal. Other bridges quickly followed: Chirk Aqueduct, Pontcysyllte Aqueduct (both still in use after renovations), numerous railway bridges across England (Water Street Bridge, Manchester terminus bridge), and others.
The architecture world stopped focusing on bridges made fully from cast iron after the collapse of the Chester and Holyhead Railway bridge across the River Dee in Chester. This 1847 collapse, less than a year after the bridge was opened, marked the end of an era of mass-produced cast iron bridges. Majority of bridges from that point on were focused on wrought iron and other materials. Other famous cast iron bridge collapse is that of Norwood Junction rail accident in 1891 that caused the deaths of over 200 people. Authorities commissioned steel replacement of thousands of cast-iron underbridge components.
Today, cast iron is used in bridge construction, but not for all of its components. Since cast iron is great at compression, it is still commonly used only for arches that are subjected to a lot of compression forces. These bridges are then augmented with components made from wrought iron that can endure a lot of tension forces and are very durable.
The construction of the bridge bought significant changes in the patter of settlement in the region of the Gorge, with added traffic that boosted the local economy of the region and enabling attracting of new settlers. Around the north side of the bridge itself, village Ironbridge was quickly formed, attracting a lot of attention from not only iron industry, but also tourists who traveled all across England to visit the region where not only Industrial Revolution started, but also place where the first cast iron bridge was built. During the decades and centuries, after the bridge was built, it was promoted by its trustees and local tourist businesses as one of the most notable locations in the entire Shropshire.
The bridge and area around the bridge received numerous repairs and modifications after the bridge itself was opened to the public in 1781. Just two years later banks and abutments of the bridge were reinforced, which not only stabilized the bridge further but also prevented future damage from potential landslides. Numerous repairs were conducted in 1784, 1791 and 1782. Its strong construction enabled it to be the only bridge on River Severn that survived the flood of February 1795 without any damage. During the 19th century, bridge receives several upgrades and replacements of components. In the early years of the 20th century, the road of the bridge was paved and continued to be used by both pedestrians and car vehicles even though the bridge continued to show the signs of fatigue. In 1923, the survey reported that the bridge was in bad condition, and safety commission restricted the use of the bridge and placed maximum weight restriction of only 4 tons. With the rise of vehicular traffic in the 1930s, the bridge was deemed pedestrian-only in 1934. Tolls for using the bridge were collected by 1950. By 1954, county council proposed that the bridge should be destroyed , even though it was by it had the designation of a Scheduled Ancient Monument.
While being closed to both vehicular and pedestrian traffic, Shropshire County Council entered into negotiations and managed to form a restoration plan that sought for £147 thousand in funds between 1971 and 1975. The restoration involved installation of the ferroconcrete inverted arch under the river to counter inward movement of the bridge abutments, removal of the filling material from south abutment, reinforcing of the arch by filling them with concrete, rebuilding of the stone abutments, building of the new toll-house/information center and replacing the tarmac decking with lighter macadam. The newly painted Iron Bridge was opened to the public on 1 January 1981.
During last decade of 20th century, the bridge was repainted and repaired in a minor fashion. In early 2017, a new restoration project for Iron Bride was announced.
Since it was created, Iron Bridge was promoted by the Ironbridge village and Shropshire businesses and organizations as one of the greatest icons of the early English industrial revolution era. Because of that, the bridge became a focal point of many works of art over the last several centuries. This includes, but is not limited to: