On this day in history….12th April 1831

On this day in history : 12th April 1831 – The Broughton Suspension Bridge in Manchester collapses – believed to have been caused by a mechanical resonance due to troops marching over it….

The iron chain suspension bridge, one of the first in Europe, was erected in 1826 to span the River Irwell between Broughton and Pendleton – now part of Salford, Greater Manchester – to link the two towns together…. It was built at the personal expense of John Fitzgerald, MP and wealthy owner of Castle Irwell House….

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Broughton Suspension Bridge after it had been rebuilt, 1883 – Public domain

The 60th Rifle Corps had been out on exercise on Kersal Moor, under the command of Lieutenant Percy Slingsby Fitzgerald – the son of John Fitzgerald…. The troops needed to cross the bridge as part of their route back to the barracks – 74 soldiers, 4 abreast began to march across…. As they did so they felt it begin to vibrate in time to their marching feet…. They found it all rather amusing and began to whistle an accompanying marching tune; the vibrations continued to get stronger….

As the head of the column approached the far side loud cracking and banging sounds were heard…. Suddenly one of the iron pillars supporting the suspension chains gave way….falling towards the bridge, dragging with it the massive stone to which it was fixed…. The bridge, now unsupported, fell into the river….

About 40 of the soldiers were hurled into the water, which lay 16-18ft below…. The river was low at the time, with around only 2ft of water – so not enough to break a fall…. Thankfully nobody was killed but around 20 sustained injuries – ranging from broken bones, to concussion, head injuries and severe bruising….

An investigation discovered a bolt in one of the stay-chains had snapped; further examination revealed it had been badly forged…. It is believed the cross-bolts had begun to bend and crack before the bridge’s collapse and it was an accident waiting to happen…. The marching troops had just sped up the process….

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Sign on Albert Bridge, London – Image credit: Iridescent CC BY-SA 3.0

After the incident the British army issued an order to ‘break step’ when marching across bridges…. The Broughton Suspension Bridge was rebuilt – but in 1924 it was replaced with a Pratt truss footbridge – which is still in use today….

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The replacement Pratt truss footbridge still in use today – Image credit: Richerman CC BY-SA 3.0