10 August 2015

Middlesbrough's Tranny



16 transporter bridges built to completion worldwide. Of those, four were in the UK: Newport, Middlesbrough, and two over the Mersey (one at Widnes, and one at Warrington). Three of the UK transporter bridges remain, at Warrington, Middlesbrough and Newport, of which the last two are still operational.

































Connecting Middlesbrough, south of the River Tees, to Port Clarence, to the north, the Tees Transporter Bridge boasts an overall length of 851 feet and a span (between the tower centres) of 571 feet. 77 feet longer than its Newport cousin, although with a 74 feet shorter span, the bridge is the longest remaining transporter in the world. (The longest ever built was that between Widnes and Runcorn: it had a main span of 1,000 feet, was 1,150 feet long overall, and was demolished in 1961.)



Commonly called the Middlesbrough Transporter Bridge, and known locally as The Tranny, the bridge was designed by the Cleveland Bridge and Engineering Co. Ltd, of Middlesbrough. It was built between 1909 and 1911 by Sir William Arrol & Co., of Glasgow, famous for construction of the Forth Bridge.

































The bridge is of cantilever form. Each half of the truss has an anchor span of 140 feet and a cantilever span of 285.5 feet. The structure employs 2,600 tons of steel, plus another 600 tons in the caissons. This compares with 1,326 tons for the more elegant Newport bridge, which relies on its suspension cables for much of the necessary tensioning.



Still operating six days a week, the bridge was Grade II* listed in 1985, with the winch house, piers, railings and gates separately listed Grade II. The gondola was replaced in 2011. Suspended from the truss, which is 140 feet above the water, this can carry nine cars and 200 people, and crosses the river in just 90 seconds.


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