IronbridgeThe Ironbridge & Tollhouse
High Street
Shropshire TF8 7JP
The Ironbridge Gorge in Shropshire, England is named after the iconic 18th century cast-iron bridge that spans the River Severn gorge.
Constructed in 1781, the bridge was the world’s first single arch bridge to be built using cast-iron. This symbol of the Industrial Revolution has been recognised by UNESCO and the whole Gorge is now a World Heritage Site.
In 1934 the bridge was closed to vehicular traffic and designated a Scheduled Ancient Monument. However, pedestrian tolls continued to be collected until the 1950s. In 1956 the County Council made a proposal to demolish the bridge and replace it with a new one. Thankfully sanity prevailed and the iconic bridge was saved, repaired, conserved and restored.
It is now protected with a Grade I listing, belongs to the Telford and Wreakin Borough Council and is cared for by English Heritage and the Ironbridge Gorge Museums Trust.
The building of the bridge heralded a radical new technology. In this article, find out why it was built and how it was constructed.
The Iron Bridge is a public access monument.
The restored Tollhouse is one of the ten Ironbridge Gorge Museums. It houses an interesting exhibition and has limited opening hours.
There are two options – tickets for a single visit to a museum or the fantastic value annual Passport Ticket which allows unlimited visits to all the sites. For more information and current prices, go to  Web:  Ironbridge/ Ticket prices.
- Walk across the bridge, following in the footsteps of millions of visitors who have admired the bridge since 1779’
- Enjoy fantastic views of the Ironbridge Gorge and River Severn;
- Discover the secrets of how and why the Iron Bridge was built in an exhibition within the original Tollhouse. (The Tollhouse is open every weekend during the local school summer holidays).
Disabled Access
Visit Duration
You should allow around 45 minutes for a visit to the Iron Bridge & Tollhouse.
A number of public cafés and pubs can be found nearby.
Contact & Further Information
Telephone   +44 (0)1952 433 424  
Why the Iron Bridge was built
In the 18th century Shropshire became a centre for industry due to the low price of fuel from local mines. The River Severn was used as a key trading route, but where it flowed through the steep gorge, it was also a barrier to travel. The nearest bridge was 1.9 miles (3 km) away and the only way of crossing the river was by ferry.
The use of the river by boat traffic and the steep sides of the gorge meant that any bridge should ideally be of a single span, and sufficiently high to allow tall ships to pass underneath.
A conventional timber and stone bridge was prohibited by the steepness and instability of the gorge sides, and there was no point where roads on opposite sides of the river converged.
In 1773 it was suggested that cast-iron would be a suitable material for a bridge across the gorge. A design was produced and a site was chosen where previously only a ferry had run. Investors raised enough funds to cover the estimated cost and ironmaster, Abraham Darby III of Coalbrookdale was chosen to cast and build the bridge.
Construction took only three months during the summer of 1779, although work on the approach roads continued for another two years. The Bridge was opened to traffic on 1st January 1781. Abraham Darby III promoted the Bridge by commissioning paintings and engravings, but he had lost a lot of money on the project, which had cost nearly double the estimate.
How was it built?
In 1779 the use of cast-iron as a structural material was a revolutionary idea. Despite its pioneering technology there were no eye witness accounts of the Iron Bridge being erected. Then, in 1997 a small watercolour sketch by Elias Martin came to light in Stockholm. Although there were a lot of of early views of the Bridge by numerous artists, this was the only one which actually showed it under construction.
The sketch showed that stone footings were built and topped by iron base plates. A pair of 70 foot (21 metre) wooden derrick poles were embedded in the river to act as cranes. They were angled slightly towards the middle of the river and were stiffened near the top by a horizontal timber brace which provided further lifting points. The whole arrangement could be lent over in either direction, upstream or downstream, to reach different positions. Castings were brought to the site by boat, probably having been cast at Bedlam Furnaces located on the north bank of the Severn just 500 metres downstream.
The arch has five parallel iron frames, built starting with the upstream one and working back towards the centre. The first pair of Inner Verticals was slotted into the base plate, one on either bank. A Lower Rib was lifted from a barge until its bottom end sat on the southern base plate and rested against the Inner Vertical. The top end was raised to the correct height, and the same process was repeated from the other bank until the two halves lined up.
The two arcs were joined at the Crown by a sophisticated scarf joint, which was secured by three large nuts and bolts. Balancing on a slender timber brace, this was a job for men with steady nerves and no fear of heights. Ropes stopped the castings tipping over at this delicate stage. According to a newspaper report, the first arch spanned the River Severn on 2nd July 1779.
Using the same scaffold frame but leaning it over slightly less each time, two more arches were completed in the same way. Temporary timber braces made the structure rigid, and these were later replaced by iron castings.
The derrick poles were next lent in the downstream direction allowing the remaining two ribs to be erected, starting with the one furthest away. All five frames were then braced by diagonal and horizontal castings, which straddled the uprights. The arches and the uprights were also tied together near the base plates by short horizontal braces. With all five Lower Rib arches in place, the ironwork was free-standing and strong enough to be used as a scaffold for lifting lighter castings. There were still no abutments at this point.
The rest of the middle frame was built next, starting with the Middle Ribs, followed by the Outer Verticals, then the Outer Ribs, all held the correct distance apart by a series of decorative radial castings. Finally the decorative Circles and Ogees were added at the upper levels. The abutments were built up to their final height behind the Outer Vertical during this process. The scaffold was dismantled and the derricks re-sited so the same sequence could be repeated for the remaining frames.
The Deck Bearers were brought in at high level from the now completed abutment on the north bank, probably having been cast in a temporary furnace in The Square next to the Bridge. Each one was different and made to measure. Each pair of straight Deck Bearers was linked at the centre by a 5 metre long curved casting called the Crown Bearer, which gripped and tightened the Crown Joint. All the joints on the Bridge were then packed with iron blocks and wedges, which were sealed in with lead.
Deck plates were probably cast in The Square and levered into place, starting with the centre one. They were located along the Deck Bearers by cast iron wedges and were topped by a road surface of clay and blast furnace slag.
Facts & Figures
The bridge is built from five cast iron ribs that give a span of 100 feet (30.6 metres). Exactly 847,800 lb or 384.6 tons (30.6 sq metres) of iron was used in the construction of the bridge, and there are almost 1700 individual components, the heaviest weighing 5.6 tons ( 5.5 long tons). Components were cast individually to fit with each other, rather than being of standard sizes, with discrepancies of up to an inch or several centimetres between 'identical' components in different locations.
There are 482 main castings, but with the deck facings and railings the number rises to 1,736.
This writer is indebted to an article entitled The Iron Bridge - How was it Built? by David de Haan for the information on this page. For more fascinating information this article can be found on Web:  BBC History/ Iron Bridge  
Getting There
The Ironbridge Gorge is in Shropshire, 5 miles (8km) south of Telford Town Centre and is well signposted from the M54 motorway, Junction 4. When you leave M54 follow the brown and white tourism signs for Ironbridge Gorge.
As you get closer to the Museums follow the specific signs: For Jackfield Tile Museum, Broseley Pipeworks Museum, Museum of The Gorge and The Ironbridge & Tollhouse follow ‘Ironbridge Museums’.
Car Parking
Car parking adjacent to the Iron Bridge & Tollhouse is Local Authority Pay & Display.
Sat Nav code for the car park is TF8 7JP.
Google Map - Iron Bridge & Toll House

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