Broughton Suspension Bridge

In 1826, John Fitzgerald, the wealthy owner of Castle Irwell House (later to become the site of the Manchester Racecourse), built, at his own expense, a {{convert|144|ft}} suspension bridge across the River Irwell between Lower Broughton and Pendleton. According to John Marius Wilson's Imperial Gazetteer of England and Wales (1870–72) all users of the bridge were required to pay a pontage to cross.{{cite web |url=http://www.visionofbritain.org.uk/descriptions/entry_page.jsp?text_id=724390&word=NULL |title=Descriptive Gazetteer Entry for Manchester |last=Wilson |first=John Marius |work=A vision of Britain through time |publisher=University of Portsmouth et al |access-date=25 February 2012}} The bridge was the only means of communication between the townships of Broughton and Pendleton{{cite news|last1=Foy|first1=T. Roby|title=Memories of old Broughton|url=https://www.britishnewspaperarchive.co.uk/viewer/bl/0000206/19140105/101/0035|access-date=29 January 2018|work=Manchester Courier and Lancashire General Advertiser|agency=British Newspaper Archive (subscription required)|date=5 January 1914}} and a source of great local pride, as the Menai Suspension Bridge had opened only that year and suspension bridges were then considered the "new wonder of the age".{{cite news |title=Broughton Bridge is falling down! |last=Smith |first=Alan |date=12 April 1975 |work=Manchester Evening News }}

On 12 April 1831, the 60th Rifle Corps carried out an exercise on Kersal Moor under the command of Lieutenant Percy Slingsby Fitzgerald,[http://www.london-gazette.co.uk/issues/18750/pages/2480 London Gazette] Issue 18750 published on 26 November 1830. Page 4 the son of John Fitzgerald, Member of Parliament and brother of the poet Edward FitzGerald. As a detachment of 74 men returned to barracks in Salford by way of the bridge,{{cite news |title=Fall of the Broughton suspension bridge, near Manchester |last=Anon |date=16 April 1831 |work=The Manchester Guardian}} the soldiers, who were marching four abreast, felt it begin to vibrate in time with their footsteps. Finding the vibration amusing, some of them started to whistle a marching tune, and to "humour it by the manner in which they stepped", causing the bridge to vibrate even more. The head of the column had almost reached the Pendleton side when they heard "a sound resembling an irregular discharge of firearms". Immediately, one of the iron columns supporting the suspension chains on the Broughton side of the river fell towards the bridge, carrying with it a large stone from the pier to which it had been bolted. The corner of the bridge, no longer supported, then fell {{convert|16|or|18|ft}} into the river, throwing about forty of the soldiers into the water or against the chains. The river was low and the water only about two feet (60 cm) deep at that point. None of the men were killed, but twenty were injured, including six who suffered severe injuries including broken arms and legs, severe bruising, and contusions to the head.

The subsequent investigation found that a bolt in one of the stay-chains had snapped, at the point where it was attached to the masonry of the ground anchor. The report criticised the construction method used, as the attachment to the ground anchor relied on a single bolt (rather than two), and the bolt was found to have been badly forged.{{cite book |last=Taylor |first=Richard |author2=Phillips, Richard |title=The Philosophical Magazine: Or Annals of Chemistry, Mathematics, Astronomy, Natural History and General Science |publisher=Richard Taylor |year=1831 |volume=ix |pages=387, 388, 389 |url=https://books.google.com/books?id=NYIqAAAAYAAJ&pg=PA384}} Several other bolts had bent but had not broken.{{cite book |last=Anon |title=Penny cyclopaedia of the Society for the Diffusion of Useful Knowledge |editor=Society for the Diffusion of Useful Knowledge |publisher=Charles Knight |year=1842 |volume=xxiii stearate-tagus |pages=ss9 |url=https://books.google.com/books?id=GxwDAAAAYAAJ&pg=PA339}} Three years previously, the engineer Eaton Hodgkinson had questioned the strength of the stay chains (compared to the suspension chains). Hodgkinson had argued that the chains should be rigorously tested, but they were not. Before the accident one of the cross bolts had started to bend and crack, although it was believed{{by whom|date=April 2021}} to have been replaced by the time of the accident. The conclusion of the investigation was that the vibration caused by the marching precipitated the bolt's failure, but that it would have failed eventually anyway.

File:Broughton bridge.jpg

File:Albert Bridge notice.JPG, London]]

The collapse of the bridge caused something of a loss of confidence in suspension bridges, with one newspaper report at the time commenting:

{{quote|From what happened on this occasion we would greatly doubt the stability of the great Menai Bridge (admirable as its construction is), if a thousand men were to be marched across in close column, and keeping regular step. From its great length, the vibration would be tremendous before the head of the column had reached the further side, and some terrific calamity would be very likely to happen.}}

This did not stop the building of more suspension bridges, and the main consequence of the collapse was that the British Army issued the order to "break step" when soldiers were crossing a bridge.{{cite book |last=Braun |first=Martin |title=Differential Equations and Their Applications: An Introduction to Applied Mathematics |year=1993 |edition=4 |page=175 |url=https://books.google.com/books?id=USWV3PP3b08C&q=Differential+Equations+and+Their+Applications:+An+Introduction+to+Applied+Mathematics |isbn=0-387-97894-1 |access-date=30 May 2009 |publisher=Springer-Verlag |location=New York}} French soldiers were also ordered to break step on bridges{{spaced ndash}}nevertheless, marching was cited as a contributing factor to the collapse of the Angers Bridge in France during a storm in 1850, killing over 200 soldiers.{{cite web |url=http://www.bridgemeister.com/bridge.php?bid=993 |title=1839 Basse-Chaîne (Angers) |last=Denenberg |first=David |work=Bridgemeister.com |access-date=2 June 2009}}

Broughton Suspension Bridge was rebuilt and strengthened, but, according to the Imperial Gazetteer of England and Wales (1870–72), it was propped temporarily whenever a large crowd was expected.{{cite web |url=http://www.genuki.org.uk/big/eng/LAN/Manchester/ImpGaz1872.shtml |title=Imperial Gazetteer of England and Wales (1870–72) |last=Wilson |first=John Marius |publisher=Genuki |access-date=31 May 2009}} The suspension bridge was eventually replaced by a Pratt truss footbridge, designed by the Borough Engineer at a cost of about £2,300, which was formally opened on 2 April 1924.{{cite news |title=New Irwell Bridge |newspaper=The Manchester Guardian |date=3 April 1924 |page=11}}

• MythBusters{{'}} "Breakstep Bridge"
• MythBusters{{'}} "Myths revisited: Breakstep Bridge"
• Millennium Bridge, London – closed after two days due to excessive vibration, caused by pedestrians synchronising their steps

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Category:Suspension bridges in the United Kingdom

Category:Bridges in Greater Manchester

Category:Bridge disasters in the United Kingdom

Category:Bridge disasters caused by construction error

Category:Bridges completed in 1826

Category:1826 establishments in England