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The Iron Bridge

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Title: The Iron Bridge  
Author: World Heritage Encyclopedia
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Subject: River Severn, John Wilkinson (industrialist), Cast iron, Industrial Revolution, Ironmaster
Collection: Arch Bridges in the United Kingdom, Archaeological Sites in Shropshire, Bridges Across the River Severn, Bridges Completed in 1779, Bridges in Shropshire, Cast-Iron Arch Bridges, Deck Arch Bridges, English Heritage Sites in Shropshire, Former Toll Bridges, Grade I Listed Bridges, Grade I Listed Buildings in Shropshire, Historic Civil Engineering Landmarks, Industrial Revolution, Ironbridge Gorge, Ironbridge Gorge Museum Trust, Museums in Shropshire, Scheduled Ancient Monuments in Shropshire, Technology Museums in the United Kingdom, Telford and Wrekin
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The Iron Bridge

Iron Bridge
The Iron Bridge
Carries Pedestrian traffic
Crosses River Severn
Locale Coalbrookdale
Heritage status Grade I listed
Design cast iron arch bridge
Longest span 100 feet 6 inches (30.63 m)
Construction begin November 1777
Construction end January 1781
Opened 1 January 1781
The Iron Bridge is located in Shropshire

The Iron Bridge is a bridge that crosses the River Severn in Shropshire, England. Opened in 1781, it was the first arch bridge in the world to be made of cast iron, and was greatly celebrated after construction owing to its use of the new material.

In 1934 it was designated a World Heritage Site. The bridge is a Grade I listed building, and a waypoint on the South Telford Heritage Trail.


  • History 1
    • Background 1.1
    • Proposal 1.2
  • Construction 2
    • Design 2.1
    • Cost 2.2
  • Later history 3
    • Repairs 3.1
    • Closure 3.2
    • Restoration 3.3
  • Artistic depictions 4
  • See also 5
  • Notes 6
  • References 7
    • Citations 7.1
    • Sources 7.2
  • External links 8



An aerial photo of the bridge, showing the close proximity of the main road alongside the river and the many building dotted nearby.
The Iron Bridge from above

  • Iron Bridge & Tollhouse – Ironbridge Gorge Museums Trust
  • Virtual tour, from the BBC (VRML plugin required, then use PgUp/PgDn to move between viewpoints)
  • River Severn Bridges
  • A geological assessment of the landslides in the Ironbridge Gorge, Shropshire (Report)
  • Iron Bridge at Structurae

External links

  • Briggs, Asa (1979). Iron Bridge to Crystal Palace: Impact and Images of the Industrial Revolution. Thames and Hudson in collaboration with the Ironbridge Gorge Museum Trust.  
  • Charlton, T. M. (2002). A History of the Theory of Structures in the Nineteenth Century. Cambridge University Press.  
  • Cossons, Neil; Trinder, Barrie Stuart (2002). The Iron Bridge: symbol of the Industrial Revolution. Phillimore.  
  • Hutton, Charles (2013) [1812]. Tracts on Mathematical and Philosophical Subjects, Comprising Among Numerous Important Articles, the Theory of Bridges, With Several Plans of Recent Improvement 1. Forgotten Books. 
  • Lay, M. G. (1992). Ways of the World: A History of the World's Roads and of the Vehicles That Used Them. Rutgers University Press.  
  • Petroski, Henry (1996). Invention by Design: How Engineers Get from Thought to Thing. Harvard University Press.  
  • Powell, John (2013). Ironbridge Gorge Through Time. Amberley Publishing.  
  • Smith, Stuart (1979). A View from the Iron Bridge. Ironbridge Gorge Museum Trust.  
  • Tilly, Graham (2002). Conservation of Bridges. CRC Press.  


  1. ^ Cossons & Trinder 2002, p. 3
  2. ^ Cossons & Trinder 2002, pp. 3–4
  3. ^ a b c d e f "History and Research: Iron Bridge". English Heritage. Retrieved 4 April 2014. 
  4. ^ a b "John Wilkinson and the Iron Bridge". Broseley Local History Society. Retrieved 4 April 2014. 
  5. ^ Cossons & Trinder 2002, pp. 4–5
  6. ^ Charlton 2002, p. 11
  7. ^ Cossons & Trinder 2002, p. 9
  8. ^ a b "Thomas Farnolls Pritchard". Retrieved 4 April 2014. 
  9. ^ Cossons & Trinder 2002, pp. 10–11
  10. ^ a b Cossons & Trinder 2002, pp. 12
  11. ^ "Why build an Iron Bridge in Coalbrookdale?". Ironbridge Gorge Museum Trust. Retrieved 4 April 2014. 
  12. ^ a b Cossons & Trinder 2002, pp. 15
  13. ^ Cossons & Trinder 2002, pp. 16
  14. ^ Cossons & Trinder 2002, p. 23
  15. ^ Cossons & Trinder 2002, p. 17
  16. ^ a b c Smith 1979, p. 4
  17. ^ a b c d e f g h i j "Iron Bridge". Retrieved 13 April 2014. 
  18. ^ a b c "The Iron Bridge - How was it Built?". BBC. Retrieved 14 April 2014. 
  19. ^ "Iron Bridge". English Heritage. Retrieved 4 April 2014. 
  20. ^ "Solved - The mystery of Ironbridge". BBC. Archived from the original on 25 October 2012. Retrieved 10 June 2014. 
  21. ^ Briggs 1979, p. 7
  22. ^ "Secrets of the past: How Ironbridge was built". Retrieved 13 April 2014. 
  23. ^  
  24. ^ Tilly 2002, p. 167
  25. ^ Cossons & Trinder 2002, p. 29
  26. ^ Cossons & Trinder 2002, p. 30
  27. ^ a b c Cossons & Trinder 2002, pp. 31–33
  28. ^ a b c Cossons & Trinder 2002, p. 47
  29. ^ "Landslides in the Ironbridge Gorge, Shropshire". British Geological Survey. Retrieved 14 April 2014. 
  30. ^ Petroski 1996, p. 161
  31. ^ a b Lay 1992, p. 272
  32. ^ Powell 2013, p. 57
  33. ^ Cossons & Trinder 2002, p. 48
  34. ^ Hutton 2013, p. 146
  35. ^ a b Cossons & Trinder 2002, p. 50
  36. ^ "A Watching Brief at the Free Bridge, Jackfield, Shropshire" (PDF). Retrieved 20 July 2014. 
  37. ^ Cossons & Trinder 2002, pp. 50–51
  38. ^ a b c Cossons & Trinder 2002, p. 51
  39. ^ Briggs 1979, pp. 50–51
  40. ^ "Ironbridge Gorge gets £12m government grant". BBC News. 4 October 2012. Retrieved 13 April 2014. 
  41. ^ Cossons & Trinder 2002, p. 52
  42. ^ Cossons & Trinder 2002, pp. 53–54
  43. ^ Cossons & Trinder 2002, pp. 52–53
  44. ^ Cossons & Trinder 2002, p. 54
  45. ^ Cossons & Trinder 2002, pp. 54–55
  46. ^ Cossons & Trinder 2002, p. 55
  47. ^ Cossons & Trinder 2002, pp. 33–34
  48. ^ Cossons & Trinder 2002, pp. 35–36
  49. ^ Smith 1979



  1. ^ For a fuller description of the background of the construction of the bridge, see Cossons & Trinder 2002, pp. 9–18.


See also

In 1979, the Royal Academy held an exhibition entitled "A View from the Iron Bridge" to commemorate the bicentenary of the bridge.[49]

Over fifty painters and engravers came to the area around Coalbrookdale during the period 1750–1830 to witness and record the rise of industry.[16] Possibly the first artist to depict the bridge was William Williams, who was paid 10 guineas in October 1780 by Darby for a "drawing" of the bridge.[47] An engraving by Michael Angelo Rooker proved popular, and a copy was purchased by Thomas Jefferson.[48]

A painting of the bridge, from mid-river, in the picturesque style of the period. Smoking furnaces can be seen in the distance and a Severn trow is alongside the bridge. Two wealthy coaches are visible, as are a well-dressed party of sightseers in a small boat. The bridge is rust-red in colour, suggesting that it was unpainted.
The painting of the bridge by William Williams

Artistic depictions

In 1999–2000, the bridge was scaffolded to allow examination by English Heritage. The bridge was also repainted and minor repairs carried out.[46]

After negotiations to raise the required funds, a programme of repairs took place on the foundations of the bridge at a cost of £147,000 between 1972 and 1975.[40] The consulting engineers Sandford, Fawcett, Wilton and Bell elected to place ferro-concrete inverted arch under the river to counter inward movement of the bridge abutments.[17][41] Construction of the arch was carried out by the Tarmac Construction Company starting in the spring of 1973, but unusually high summer floods washed over the cofferdam, frustrating hopes that the work could be done in a single summer.[42] Filling material was removed from the south abutment to reduce its weight, and the arch through it was reinforced with concrete.[43] The road surface was replaced with a lighter macadam, the stone of the abutments was renewed and the toll-house was restored as an information centre.[44] In 1980, the structure was painted for the first time in the 20th century, and the work was complete for the bicentenary of the opening, which was celebrated with a pig roast on 1 January 1981.[45]

The brick tollhouse at one end of the bridge


A 1923 report by Mott, Hay and Anderson suggested that other than the paintwork, the main span of the bridge was in good condition. It was suggested that the metal deck of the bridge was dangerously heavy, and that after removing the dead weight the bridge should be reopened to vehicles no heavier than 2 tonnes (2.0 long tons; 2.2 short tons) and restricted to the centre of the roadway.[38] A weight limit of 4 tonnes (3.9 long tons; 4.4 short tons) was imposed, but the housing boom of the 1930s meant that drivers distributing tiles produced at Jackfield were insistent that they should be allowed to use the bridge, so the trustees took the decision to close the bridge to vehicular traffic with effect from 18 June 1934.[38] That same year, it was designated a Scheduled Ancient Monument.[17] Tolls for pedestrians were collected until 1950, when ownership of the bridge was transferred to Shropshire County Council.[39] The tolls collected only marginally covered the cost of collection, leaving no money for conservation, and the bridge had not been cleaned or painted for many years.[38] In 1956 the County Council made a proposal to demolish the bridge and replace it with a new one, but this plan did not come to fruition.[4]

Antique table of bridge tolls now displayed on the outside of the toll house. Tolls range from a halfpenny for a pedestrian to two shillings for a large coach
Table of tolls


On 24 August 1902, a 30 feet (9.1 m) length of parapet collapsed into the river, and a section of deck plate weighing around 5 cwt fell from the bridge in July 1903.[35] The opening of a toll-free concrete bridge in 1909 caused concern among the trustees, but it continued to be used by vehicles and pedestrians.[36][37]

In 1800 the trustees commissioned repairs which lasted for several years, and involved the replacement of the stone land arches with wooden ones to relieve pressure on the main span.[17][28] A proposal to built a rigid support between the abutments to keep them part was found to be impossible with the available technology, but was achieved during the later restoration of the bridge in the 1970s.[33] In 1812, its construction was described as "very bad" by Charles Hutton, and he predicted that it would not last for long, "though not from any deficiency in the iron-work."[34] The timber arches were replaced with cast iron ones in December 1820, and further repairs were necessary throughout the remainder of the 19th century.[17][35]

It was the only bridge on the River Severn to survive the flood of February 1795 undamaged, due to its strength and small profile against the floodwaters.[30] The medieval bridge at Buildwas was replaced with a cast iron bridge by Thomas Telford, which, by virtue of superior design, required half the quantity of iron despite a longer span of 39 metres (128 ft).[31][32] The Buildwas bridge survived until 1906.[31]

[28][17] The Gorge is very prone to landslides, and over 20 are recorded in the [17] Cracks were found in the stone land arch on the south side in December 1784, and the neighbouring abutment showed signs of movement.[28] In July 1783, a 35-yard (32 m) wall was built in order to prevent the north bank from slipping into the river.


The opening of the bridge resulted in changes in the pattern of settlement in the Gorge, and roads around the bridge were improved in the years after its construction.[27] The town of Ironbridge, taking its name from the bridge, developed at the northern end.[27] The trustees, as well as local hotel keepers and coach operators, promoted interest in the bridge among members of polite society.[27]

Radial 'hourglass' supports of the bridge, cracked through the dovetails at their end
Cracked supports

Iron members of the bridge, one showing a visible crack and one repaired by steel sandwich plates bolted around it
Crack and repairs in bridge

Later history

Darby had agreed to construct the bridge with a budget of £3,250 and £3,250 was raised by subscribers to the project. Whilst the actual cost of the bridge is unknown, contemporary records suggest it was as high as £6,000, the excess being born by Darby, who was highly indebted from other ventures as well.[25] However, by the mid-1790s the bridge was highly profitable, and tolls were giving the shareholders an annual dividend of 8 per cent.[26]


Two supplemental arches, of similar cast iron construction, carry a towpath on the south bank and also act as flood arches. A stone arch carries a small path on the north, town, bank.

Decorative rings and ogees between the structural ribs of the bridge suggest that the final design was of Pritchard, as the same elements appear in a gazebo he rebuilt.[16][23] A foreman at the foundry, Thomas Gregory, drew the detailed designs for the members, resulting in the use of carpentry jointing details such as mortice and tenon joints and dovetails.[3][17][24]

The bridge is built from five cast iron ribs that give a span of 30.6 metres (100 ft).[17] Exactly 378 long tons 10 cwt (847,800 lb or 384.6 t) of iron was used in the construction of the bridge, and there are almost 1700 individual components, the heaviest weighing 5.5 long tons (5.6 t).[17][21] Components were cast individually to fit with each other, rather than being of standard sizes, with discrepancies of up to several centimeters between 'identical' components in different locations.[22]


More information about how the bridge was built came from the discovery in 1997 of a small watercolour by Elias Martin in a Stockholm museum, showing the bridge under construction in 1779.[18] A half-size replica of the main section of the bridge was built in 2001 as part of the research for the BBC Timewatch programme which was shown in 2002.[18][20]

The masonry and abutments were constructed between 1777 and 1778, and the ribs were lifted into place in the summer of 1779.[16][17] The nascent bridge first spanned the river on 2 July 1779, and it was opened to traffic on 1 January 1781.[18][19]

The site, adjacent to where a ferry had run between Madely and Benthall, was chosen for its high approaches on each side and the relative solidity of the ground.[3] The Act of Parliament described how the bridge was to be built from a point in Benthall parish near the house of Samuel Barnett to a point on the opposite shore near the house of Thomas Crumpton.[14] Pritchard died on 21 December 1777 in his tower-house at Eyton on Severn, only a month after work had begun, having been ill for over a year.[3][8][15]

Pedestrians crossing the Iron Bridge with Ironbridge in the background


In March 1776, the Act to build a bridge received Royal Assent with legal counsel from Thomas Addenbrooke, and Abraham Darby III was commissioned to cast and build the bridge.[3][11] In May 1776, the trustees withdrew Darby's commission, and instead advertised for plans for a single arch bridge to be built in "stone, brick or timber."[12] No satisfactory proposal was made, and the trustees agreed to go with Pritchard's design, but there was continued uncertainty about the use of iron, and conditions were set on the cost and duration of the construction.[12] In July 1777 the span of the bridge was decreased to 90 feet (27 m), and then increased again to 100 feet 6 inches (30.63 m), possibly in order to accommodate a towpath.[13][note 1]

During the winter of 1773–74, local newspapers advertised a proposal to petition Parliament for leave to construct an iron bridge with a single 120 feet (37 m) span.[10] In 1775, a subscription of between three and four thousand pounds was raised, and Abraham Darby III, the grandson of Abraham Darby I and an ironmaster working at Coalbrookdale, was appointed treasurer to the project.[10]

In 1773, architect Thomas Farnolls Pritchard wrote to a local ironmaster, John Wilkinson of Broseley, to suggest building a bridge out of cast iron.[8] Pritchard had previous experience with the design of both wooden and stone bridges, and it is possible that he had integrated into these designs elements of iron.[9]


The Iron Bridge was the first of its kind to be constructed, although not the first to be considered or the first iron bridge of any kind. An iron bridge was partly constructed at Lyons in 1755, but was abandoned for reasons of cost,[6] and a 22.2 metres (73 ft) span wrought iron footbridge over an ornamental waterway was erected in Yorkshire in 1769.[7]

[5] The steepness and instability of the banks was problematic for building a bridge, and there was no point where roads on opposite sides of the river converged.[4][3]

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