On 17 July 1876, the world’s largest swinging bridge – a marvel of hydraulic engineering – opened for the first time, allowing access to the upper reaches of the River Tyne.

Since that day, the Newcastle Swing Bridge, designed by William Armstrong, one of the greatest names in British engineering, has opened on about 300,000 occasions for the passage of about half-a-million vessels.

An unusual hydraulically-powered structure built for both road and rail, Ashton swing bridge was erected in 1905-6 for Bristol Corporation and the Great Western Railway. Its chief engineer was J C lnglis and the contractor John Lysaght. Armstrong Whitworth and Co was responsible for the hydraulics.

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The Whipple Murphy truss moveable span, which has remained shut since February 1934, is 202 feet in length and weighs in at 1,000 tonnes. It could open both ways, with a reversible motor housed in a signal cabin perched above the road deck. The hydraulics drained the dock system of 182 gallons of water every time the bridge opened – and, on average, it did so ten times a day. The mechanism was interlocked with the signal boxes on either side of the river, making it impossible for signals to be cleared unless the span was locked in the closed position.

Bristol Corporation rescinded the railway’s obligation to maintain the swing aparatus in 1951, since which time is has been fixed shut. The road deck and signal cabin were removed following the completion of new local roads in 1965.