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Wearmouth Bridge (1796), site of
River Wear, Sunderland, Tyne & Wear, UK
associated engineer
Rowland Burdon
Thomas Wilson
Robert Stephenson
George Henry Phipps
date  24th September 1793 - 9th August 1796, 1857 - 5th March 1859
era  Georgian  |  category  Bridge  |  reference  NZ395574
ICE reference number  HEW 528
Until the Wearmouth iron bridge (now demolished) was built at Sunderland in 1796, ferries were the only way to cross the River Wear downstream of Chester-le-Street. It was constructed using small cast iron elements held together with wrought iron ties, unlike the world’s first cast iron bridge at Coalbrookdale (1779-81), which has much larger castings and shares many features with timber bridge design.
The bridge's location, between Monkwearmouth and Bishopwearmouth, where the river runs deep near the south bank, was chosen so that vessels were not at risk of grounding. The bridge had to be high enough that 305 tonne ships could pass beneath it without lowering their masts. Many prominent engineers of the time were involved with the design — a process administered by MP and local freemason Rowland Burdon, who provided most of the finance.
At first Burdon favoured a stone bridge and Robert Shout Jr, engineer to Sunderland Harbour, provided the first design in 1788 — a 51.8m single span. In about 1792 John Nash was employed as the bridge’s architect, though his design for a 61m masonry arch was dismissed on the grounds of feasibility and cost and he left the project in 1793. Burdon then sought advice from Robert Mylne and John Soane. The longest stone arch known to Mylne was 54.6m and yet Burdon hoped to span a gap of almost 72m between banks.
Also, the temporary works that would be required during construction — bearing the weight of the whole arch until the keystone was locked into place — would have been expensive and cumbersome, obstructing shipping to the detriment of river trade. Whitby Harbour engineer Jonathan Pickernell Sr produced a design for stone bridge centring in 1794.
Meanwhile, in 1791 Thomas Paine (author of The Rights of Man) submitted a design for a single span iron bridge. As hopes for a stone bridge faltered, Rotherham iron founder Joshua Walker revisited Paine's earlier ideas. He and Burdon envisaged an iron bridge that had many similarities with masonry arches, including voussoirs and keystones in iron — an idea also claimed by John Rastrick. Burdon and engineer Thomas Wilson modified the design to be more like Montpetit’s Seine Bridge (1783) to include connecting straps.
Burdon patented his final design for Wearmouth Bridge in 1795, shared equally with Wilson and financial manager Michael Scarth.
The bridge had a single span of 71.9m between masonry abutments and its six ribs, spaced apart by tubes, gave it a width of 9.75m. Each rib was assembled from 105 castings and formed a segment of a circle with a rise of 10.4m. The spandrels were filled with cast iron circles up to 3.96m in diameter. Coal varnish was used to protect the iron from corrosion.
The springing was some 29m above river level at low tide and 25m at high water. A 6.7m wide gravel carriageway was carried on a timber planked deck atop the ribs, with 1.5m wide footways of stone flags and iron palings either side.
Work on the abutments began in October 1793, shortly after the foundation stone was laid. They were of solid rubble masonry set with lime mortar and faced with dressed stonework. The south abutment had a rock foundation some 6m above the water and was 21.3m high. On the north bank, the abutment was founded on a marl-filled limestone hollow close to low water level and was 27.4m high — a large arch was incorporated to reduce its weight.
The centring required for an iron (rather than stone) arch was more like scaffolding than massive supporting piers. The timber framework for this was constructed on land, floated into the water and raised on two caissons sunk in the river bed. The 264 tonne iron arch was completed in 10 working days, while shipping passed unimpeded beneath the scaffold.
The temporary supports were about to be removed in autumn 1795 when a storm displaced the staging and moved the arch 250mm. Workmen hastily removed the connecting wedges and the arch of (comparatively) elastic metal apparently sprang partly back into position. No further work was deemed necessary on the alignment.
HRH Prince William, Duke of Gloucester, officially opened Wearmouth Bridge on 9th August 1796. As was usual at the time, tolls were levied to recoup the cost of construction. Its commissioners were also responsible for running the ferries, which continued to operate. The bridge became free to pedestrians in 1846 and was completely toll free by November 1885.
In 1804, a bulge was visible on the east side of the arch, probably a legacy of the storm during construction. John Grimshaw was called in to advise and he concluded that the arch was now some 500mm out of line. Most of the spacing tubes were gone and the ribs were only held together by the timber framework on top. His remedial work inserted diagonal bracing between the ribs and wedged the arch back into line.
In 1841 more repairs were carried out under the supervision of Thomas Moore, who built Monkwearmouth Station (1848), with advice from Robert Stephenson.
In 1853, blasting work on the south river bank for a nearby bottle works caused extensive damage to one abutment. Traffic over the bridge was increasing as industries grew. Safety was a concern, and Stephenson and his assistant George Henry Phipps recommended reconstruction. The superstructure was dismantled, leaving the ribs exposed — they were still 400mm out of line. The abutments were raised and widened, which decreased the gradient on the north side to 1 in 47 and gave a level approach on the south side.
In 1858, three wrought iron box girders were inserted between the pairs of ribs, the carriageway was widened to 12.65m and the footways to 2.3m. Large panels engraved with Nil Desperandum Auspice Deo ("Do not despair, have faith in God") were added.
In 1879 rails were laid and trams ran over the bridge without further modification being necessary. But by 1913 the bridge was again deteriorating and in 1927-29 a new structure was built around it on the same spot before the remains of the original were demolished. The new bridge is the one we can see today. Traffic across the bridge and shipping beneath it were unaffected by the new works.
Supervising engineer (1793-6): Thomas Wilson
Supervising engineer (1841): Thomas Moore
Supervising engineer (1857-9): George Henry Phipps
Bridge acstings (1793-6): Walkers of Rotherham
Masonry (1857-9) B.C. Lawton
Ironwork (1857-9): Hawks, Crawshay & Sons
Research: ECPK
bibliography
"The Wearmouth Bridge" by Gillian Cookson
undated, available at www.englandspastforeveryone.org.uk
"The Wearmouth Bridge", Local Studies Centre Fact Sheet Number 7
available at www.sunderland.gov.uk
"Bridges of the River Wear" by Keith Cockerill
The People's History Ltd, Seaham, County Durham, 2005
www.wearsideonline.com
reference sources   CEH NorthSmiles2
Location

Wearmouth Bridge (1796), site of