Proceedings of ICE Civil Engineering 159 May 2006 Pages 88–95 Paper 13981

Keywords bridges; cables & tendons; history Union Chain Bridge: linking engineering

Civil and marine engineering have long been linked, but Gordon Miller ARIBA perhaps no more symbolically than by the Union Chain Bridge is an architect in Berwickshire, UK between and over the . It was built 186 years ago by Sir Samuel Brown, who made the transition from Royal Navy captain to designer of the world’s longest iron suspension bridge in one single leap. This paper reports on his remarkable eight-year journey, from leaving the Royal Navy in 1812 to start an anchor-chain business to building the record-breaking Union Chain Bridge in 1820. He went on to design the Brighton Chain Pier and supply Isambard Kingdom Brunel with chains for his Great Eastern steamship, while his company remained the navy’s sole chain supplier for over a century. Union Chain Bridge, which still carries road traffic today, thus serves as an inspiration to all engineers of the benefits of cross-disciplinary thinking.

Alexander Naysmith’s painting of Sir when it opened and the fi rst of its kind to Samuel Brown’s Union Chain Bridge carry road traffi c. It is now the oldest iron between England and Scotland at Berwick- chain suspension bridge in the UK still upon-Tweed was unveiled at its new home carrying public road traffi c, albeit only in Paxton House, Berwickshire by the one vehicle at a time. speaker of the House of Commons in July 2004 (Fig. 1). Naysmith was commissioned A captain with ambition to produce the work by the Berwick and North Durham Turnpike Trust in celebra- Sam Brown established a reputation tion of the bridge’s opening in July 1820. as a dedicated businessman and engineer The painting was presented to the then (Fig. 2). Entering the Royal Navy in 1795 Captain Brown, who had left the Royal he rose to the rank of commander in 1811 Navy only eight years earlier and never and accepted the rank of retired captain in built a bridge before, upon the successful May 1812, during which time he ‘wrestled outcome of his remarkable ‘bridge experi- mentally’ with the huge loss of ships owing ment’. It remained in his possession for to the failure of rope rigging and anchor the rest of his life. cables. Troubled by this loss to the navy and The 129 m long bridge, which 186 not least by his own ambition, Brown set years later still spans the River Tweed about experimenting to fi nd an alternative between Horncliffe in material to the hemp ropes used at the time. and Fishwick in Borders, was the longest In 1805 he lodged in two rooms of a iron chain suspension bridge in the world house in Dove Court, Lombard Street.

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Fig. 1. Alexander Naysmith’s contemporary painting of Union Chain Bridge linking England and Scotland across the River Tweed. When it opened in 1820 it was the world’s longest iron suspension bridge (source: Paxton Trust)

With little money he managed to employ iron chains could be tested for consist- blacksmiths to produce wrought iron ent strength. In 1811 Brown achieved chain at premises in London at Narrow the commercial breakthrough that he Street and Borough.1,2 By 1806 Brown had long been aiming for when the Royal was suffi ciently confi dent in the use Navy adopted his chains for ground and behaviour of wrought iron that he tackle. This gave him the fi nancial stabil- equipped HMS Penelope, a vessel of ity to engage in the development of other 400 t, with iron rigging, stays and cables. applications for the material. He started Penelope embarked upon a test voyage producing ideas and calculations for to Martinique. Despite encountering severe suspension bridges and in 1813 designed weather conditions she returned unscathed and built a model of 32 m span.1 from her four-month ordeal. Encouraged by In 1816 Brown obtained a patent for his fi ndings, and with the fi nancial assist- chain manufactured by a new process4 fol- ance of his cousin Samuel Lenox, Brown lowed by another in 1817 for chain bridge obtained his own manufacturing works on construction.5 The fi rst patent described the Isle of Dogs in 1808.1,3 the manufacture of chain composed of oval-shaped links side-welded with broad- Fig. 2. Union Chain Bridge designer Sir From ships to suspension bridges ended studs, the link formed on special Samuel Brown (1776–1852) served as a machinery to Brown’s design and covered captain in the Royal Navy before becoming Joseph Bramah’s hydraulic press de- in the patent. The method remained un- a manufacturer of iron chains and designer velopments for the testing of materials changed well into the twentieth century. of suspension bridges (courtesy East Sussex County Council) in tension in 1810 meant that Brown’s Exactly how Brown came to work on

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Fig. 3. John and Thomas Smith’s 1817 chain suspension bridge over the Tweed at Dryburg Abbey was the first in Britain, but blew down the following year

(a) (b)

1” = 25 mm

Fig. 4. Brown’s bar-link system for suspension bridges was (a) patented in 1817 and (b) first put to use on the Union Chain Bridge in 1820

the Union Bridge project is not known, in Britain (Fig. 3). Completed in 1817, American Thomas Pope’s 1811 publica- but circumstances at the time were in John and Thomas Smith’s 1.2 m wide, tion, A Treatise on Bridge Architecture,11 his favour. Admiral Sir David Milne was 79 m long footbridge at Dryburg Abbey in which he pointed out that ‘there can be a great friend of George Home, who was supported by inclined iron chains in no security in a bridge wholly dependent became involved with introducing the a modern cable-stay arrangement, but on two chains’.10, 12, 13 In any event the General Turnpike Act in 1822. Following was blown down in a storm the following Runcorn project was unable to get suf- the Napoleonic Wars, attention in the UK year. Although minor in size, the failure fi cient funding. became focused on the importance of of the bridge and its subsequent rebuild- roads, including bridges, as a national re- ing with twin catenary chains attracted a Union Bridge evolves into reality quirement. With the turnpike system, the visit from potential funders of a proposed existence of tight fi nancial limits precluded iron chain suspension bridge designed by Brown made his initial offer to continued construction of monumental Thomas Telford in 1814 at Runcorn Gap construct a suspension bridge for the stone-arch bridges, such as Smeaton’s over across the Mersey.7–9 Berwick and North Durham Turnpike the River Tweed at (1763). With confi dence bolstered, the Trust over the River Tweed based upon Since Brown enjoyed the confi dence of Runcorn project also invited Brown for a specifi cation and signed drawing dated Milne through earlier naval associations, it a scheme to ‘throw a bridge of suspen- September 1818. His initial proposal was is more than likely that his activities would sion over the Mersey’. Thomas Telford for a span of 119 m between free-stand- be mentioned to Home. Brown’s work was later changed his mind about his own ing stone piers at New Water Ford for the also recognised by future ICE president design owing to his concern about the sum of £4900. John Rennie, who had inspected the 1813 key suspension element, though Brown It was subsequently decided the deck bridge model and, in turn, shared close remained dedicated to his bar-link prin- needed to be substantially higher to re- friendship with Milne.6 ciple (Fig. 4). He may well have known main clear of fl oodwaters so a site was By this time fi ve suspension foot- about the American James Finley’s 1810 chosen 300 m upstream where the river bridges had already been erected over paper ‘Principles of stiffened deck sus- banks were higher. However, the England the Tweed and its tributaries, including pension bridge design’ (see reference 10). bank consisted of an 18 m high sandstone the fi rst chain suspension bridge built Such activity was referred to in fellow outcrop that would need cutting back to

90 CIVIL ENGINEERING UNION CHAIN BRIDGE: LINKING ENGINEERING

(a) A1 0km5(b) Bankhead A6105 Shoal ruins bank Old Road Paxton Berwick -upon B6461 -Tweed Boathouse Cottage River Tweed B6461 River Tweed Union Tweedhill ENGLAND Chain North Fishwick Bridge Sea Scotch New Water Shiel Horncliffe

Bridge

Horncliffe Road

A698

SCOTLAND A1

B6525 0 m 150

Fig. 5. Union Chain Bridge: (a) location and (b) site plan

Fig. 6. Elevation of Union Chain Bridge looking from the north. To create space for the road on the east bank, the eastern suspension tower was set back into the sandstone cliff, requiring longer and stronger chains

accommodate the new bankside approach that month, the chairman of trustees road (Fig. 5). To make room for the ap- addressed all present, expressing ‘great Fig. 7. The original three-tiered suspension proach road, the eastern pier was set back confi dence in our contractor’ and empha- chains were supplemented by steel cables into the rock face, extending the length of sising the opinion that the bridge ‘is still and additional suspension rods in 1902 (cour- the catenary chains to 129 m, some 20 m an experiment’. tesy of Northumberland County Council) longer than the deck (Fig. 6). The result- Brown then started work on the ing lack of suspension rods at the eastern detail design and had the ironwork end is a detail not realised in Naysmith’s manufactured and shipped to site during painting. December 1819. Although the winter Brown’s fi nal design for the new site weather was extremely bad, all work was It went straight was a signifi cant advance over his initial completed with a grand opening in July offer, with three tiered pairs of wrought- 1820, the project taking exactly one year into the record iron rods instead of the single bank origi- from start to fi nish. It went straight into nally proposed. Apart from the possibility the record books as the world’s longest books as the of Pope’s infl uence, the delay certainly iron chain suspension bridge and the fi rst gave time for an exchange of views with to carry road traffi c. world’s longest other engineers including John Rennie and Robert Stevenson.14 The revised cost, Progressively strengthened over time iron chain including road works, was £6449. After considerable argument between During its early years the bridge was suspension Brown and the trustees concerning cost, principally used for carting lime and coal, and with the authority of an 1802 Act of saving an 18 km detour to the nearest bridge and the Parliament, it was decided in July 1819 crossing at Berwick-upon-Tweed. The at a meeting in Berwick-on-Tweed to ac- suspension points were strengthened in first to carry cept Brown’s revised design. Following 1837.15 Later, great numbers of cattle the foundation stone ceremony later were herded across it and, though well road traffic

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Table 1. Summary of significant events in Union Chain Bridge’s long history maintained, severe deck decay set in. In Date Event 1871 the wrought iron deck transoms 7 Sept 1818 Samuel Brown’s dated bridge proposal drawing. and support run-bars were replaced.16 3 Jul 1819 Inaugural meeting of Berwick and North Durham Turnpike trustees 16 Jul 1819 Trustees approve bridge contract By 1902 higher traffi c loading led the 26 Jul 1819 Bridge foundation stone laid local bridge surveyor to conclude that 21 Aug 1819 Bridge proposal drawing engrossed as contract drawing by trustees 26 Jul 1820 Bridge completed, offi cial opening increased platform support and stiffening 30 Sep 1820 Arguments as to costs, increased by 25% was necessary. A supplementary weight 4 Jun 1821 Final account agreed at £6449 18s 8d restriction was imposed and additional 1837 Substantial repairs to bridge platform 1871 Complete platform re-designed and replaced cables, suspension rods, deck transom Mar 1883 End of turnpike tolls supports and bracing rods were incor- 7 Apr 1884 Tweed Bridge Trust formed 24 Aug 1887 Surveyor to the trust recommends maximum moving load of 28 t porated (Fig. 7). Table 1 catalogues the 1891 Chains over English pier bearings reinforced, anchorage strengthened signifi cant events in the bridge’s life to 1901 Bottom pairs of chains over Scottish tower reinforced 1902 Platform timbering replaced date and Fig. 8 details how the deck was 1903 Addition of auxiliary cables and anchorage improvements progressively strengthened. 1912 Finance Act 1910, bridge valuation £3650, site value £40 Greater decline occurred during the 1932 Platform timbering replaced 1934 Bridge toll cottage condemned next 71 years with less maintenance and 1953 Cottage demolished, pier refaced little regard for traffi c loads. The neglect 1974 Complete platform redesigned and replaced, suspension chains overhauled, Scottish tower bearings overhauled persisted throughout World War II and, with the road no longer regarded as being

(a) (b) 5' 0" 5' 0" 18' 1" 12' 0"

1820–1837 1820–1837

12' 3"

1837–1871 1837–1871

12' 0"

1871–1902/3 1871–1902/3 Platform bracing introduced 1871 12' 8"

1903–1974 1903–1974 Supplementary SWR cable and suspension rods introduced 1903 12' 9"

1974– 1974–

Fig. 8. The bridge deck has been progressively strengthened four times since first built, as can be seen here in the evolution of (a) its cross-section and (b) its long section (1' = 0.3 m, 1" = 25 mm)

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vital, the authorities downgraded the ap- proach roads to class III. In 1948 the county engineer became concerned about the ever-increasing weight of traffi c resulting from the de- struction of the Whiteadder Bridge across in nearby Berwick- upon-Tweed after torrential rain and fl ooding, during which the River Tweed had risen to within touching distance of the Union Chain Bridge deck. Further traffi c control was introduced with an order under the Road Traffi c Act of 1950 imposing weight restriction. Demolition of the former toll keeper’s house attached to the English side pier face in 1955 also removed its residents who, like all before, cared a great deal Fig. 9. Reconstruction of the timber bridge deck was last carried out in 1974–1975 (courtesy of Northumberland County Council) about the bridge, clearing the deck and

Fig. 10. Union Chain Bridge is now the world’s oldest suspension bridge still carrying public road traffic, though only one car at a time is permitted to use it (courtesy of Northumberland County Council)

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Fig. 11. The 186-year-old crossing is now a grade I listed building and scheduled ancient monument (photograph by David Home-Miller)

Fig. 12. Brown went on to supply chains for Isambard Kingdom Brunel’s Great Eastern steamship, but his greatest engineering achievement is generally considered to be the Brighton Chain Pier of 1823 (courtesy of ICE archive)

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reporting on its condition. At that time the county surveyor took the pessimistic During the remainder of his lifetime view that the bridge was nearing the end of its days and that a new bridge would Brown was involved in the design and be diffi cult to justify.17 or the supply of chain-link ironwork for Subsequent routine inspection revealed serious deterioration of the steel angles some 18 suspension bridges or piers and that support the road deck platform. This prompted the surveyor to make a detailed proposals for another 12. The Brighton inspection of the entire structure in March 1973. His report contained unwelcome Chain Pier of 1823 was probably his information outlining repairs and new work requiring the bridge closure for six months. greatest engineering achievement Work commenced in May 1974, revealing more extensive repairs than had been an- ticipated and that a compete replacement of the deck was required (Fig. 9). Eventually References Fayette County, Pennsylvania—Jacob’s Creek Bridge 1801. In The Portfolio, vol. III, June 1810, all work was completed at a cost of £82 000 1. JONES S. K. A Link with the Past—A History of No. 6, pp. 441–453. in 1975, the surveyor commenting that the the Newbridge Works of Brown Lenox and Co. Pontypridd. Brown Lenox & Co., London, 11. P OPE T. A Treatise on Bridge Architecture. New cost ‘is a sobering thought in relation to the 1978. York, 1811. ICE accession no. P811 POETBE. importance of the bridge in the roadwork 2. HORWOOD R. Maps Iron Cable Manufact’y Isle 12. BARLOW P. A Treatise on the Strength of Timber, pattern but hopefully its very unique posi- of Dogs—GLC Archives, 4th edn. W. Faden, Cast Iron, Malleable Iron and other Materials. tion in civil engineering will warrant high London, 1819. ICE Library, 1845. 18 priority’. The bridge is now a grade I listed 3. MILNE-HOME G. Biographical sketch of David 13. TELFORD T. Report of the select committee building and scheduled ancient monument, Milne-Home. Pub. David Douglas, Edinburgh appointed to consider the most practical and and is maintained by Northumberland 1891-H.M.C. Her Majesty’s Stationery expedient mode of effecting the proposed County Council (Figs 10 and 11). Offi ce, 1902. bridge at Runcorn. City of Liverpool Record 4. BROWN S. and THOMAS P. Specifi cation—A Offi ce, Liverpool, 13 Mar 1817. Brown’s engineering contribution Chain or Chains Manufactured in a Peculiar 14. Berwick Advertiser, 3 April, 31 July, 7 August 7 Manner by a New Process and Certain 1819 and 4 March, 13 May, 22 July, 5 August Apparatus and Implements in Performing the 1820. During the remainder of his lifetime Executing the Same. Patent No. 4090, 17 15. BERWICK AND AND ISLANDSHIRES Brown was involved in the design and or February 1816. TURNPIKE TRUST (formerly The Berwick the supply of chain-link ironwork for some 5. BROWN S. Construction of Bridges—Invention Turnpike Trustees). Minutes of Proceedings, 8 18 suspension bridges or piers and propos- or Improvement in the Construction of a Bridge, June 1837. als for another 12. The Brighton Chain by the Formation and Uniting of its Component 16. SANDERSON, MCCREATH & EDNEY SOLICITORS. Pier of 1823 (Fig. 12) was probably his Parts in a Manner not Hitherto Practised. Patent Reports upon the bridge condition by Mr W greatest engineering achievement and in No. 4137, 10 July 1817. Smith, architect with plan of repairs neces- sary at Union Bridge, Berwick upon Tweed, 1838 Queen Victoria honoured him with 6. RENNIE J. Letter of Molle, 11 November 1818, 1871. a knighthood. The 350 m long, fi ve-span MS, ICE Library, X, 21–3 7. DREWRY C. S. A Memoir on Suspension Bridges. 17. Berwick Advertiser. Reports from pier lasted for 73 years. Longman, London, 1832, Section III, pp. Northumberland and Berwick County His company Brown Lenox & Co. also 43–49. Council concerning the future of the Bridge went on to produce chains for Isambard 8. The Kaleidoscope, New Series. British Chief Engineer to the Ministry of Transport Kingdom Brunel’s Great Eastern steam- Architectural Library (RIBA), London, 1822, imposing weight restrictions, 10 Aug 1948. ship in 1858—immortalised as the back- 11, No. 105, 237–256. NLS Ref NJ259. 18. ARTHUR B. Northumberland County Council drop in Robert Howlett’s well-known pho- 9. HAMILTON J. Letter covering archive extract surveyor reports to the Bridge Trustees, tograph of Brunel. The company was also from text on suspension bridges by John November 28 1973. Detailed Drawings N.B/ the sole supplier of Admiralty chain from and Thomas Smith, part of their paper on C2/TBT/2/38, August–September, 1973; B/ C2/TBT/2/39, March, 1974; B/C2/TBT/2/44, 1808 to 1916. Whinstone construction, 2 November 1835, November 1975. Though Brown was not a member of the Edinburgh, 2 February 1878. 10. OLDSCHOOL O. A destination of the Patenet 19. RENNIE J. Presidential address, Proceedings of Institution of Civil Engineers he enjoyed Chain Bridge; invented by James Finley of the Institution of Civil Engineers, 1846, V. the respect of president Sir John Rennie, who in his 1846 presidential address ac- knowledged Brown’s great contribution What do you think? to engineering: ‘Captain Brown…who If you would like to comment on this paper, please email up to 200 words to the editor at [email protected]. had previously brought chain cables into If you would like to write a paper of 2000 to 3500 words about your own experience in this or any related area of England of the improved system of the bar civil engineering, the editor will be happy to provide any help or advice you need. link which is now so generally adopted’.19

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