Monday, December 23, 2013

Transporter Bridges

A transporter bridge is a type of movable bridge that carries a gondola across a river. The bridge usually consists of a framework of steel girders spanning the river or waterway to be crossed, but instead of a roadway or railway lines built on a deck spanning the gap, a platform or "gondola" is suspended by steel cables from a moveable trolley running across the top of the span on a track. The trolley moves across the span taking with it the gondola, onto which are loaded the passengers and vehicles. The transporter bridge is a rare type of bridge, with fewer than two dozen built all over the world. Only eight operate today.

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The iconic Middlesbrough Transporter Bridge across River Tees. Photo credit

The idea of transporter bridges were born out of the need to cross rivers or waterways were it was inconvenient or too expensive to build conventional high-level bridges with sufficient navigable headroom to allow tall ships to pass. The concept was first mooted in 1872 when Charles Smith, Manager of the Hartlepool Iron Works, proposed a scheme to construct a transporter bridge across the River Tees to the Middlesbrough Corporation. He called it a "bridge ferry". However the scheme was not pursued and it would not be until another twenty years that the idea of transporter bridges to carry traffic across a river would be considered useful.

The first transporter bridge, Vizcaya Bridge was built in Portugalete, Spain, in 1893, and is still in regular daily use. The design from Alberto Palacio inspired others to attempt similar structures. The idea came about in locations where it was seen as impractical to build long approach ramps that would be required to reach a high span, and in places where ferries are not easily able to cross. Because transporter bridges can carry only a limited load, the idea was little used after the rise of the automobile.

The first such bridge built in France, the 1898 Rouen bridge crossing the Seine, was destroyed by the French army to slow down German troops in World War II. Transporter bridges were popular in France, where five were erected and another partially completed. The Rochefort-Martrou Transporter Bridge, built in 1900 in Rochefort, is still used today during the summers.

The United Kingdom has four transporter bridges, though Warrington Transporter Bridge is disused and the modern Royal Victoria Dock Bridge, though designed with the potential to be used as a transporter bridge, has so far only been used as a high-level footbridge. The Newport Transporter Bridge, built in 1906 across the River Usk in Newport, and the Middlesbrough Transporter Bridge, built in 1911 across river Tees, are the two transporter bridges in the U.K. that are still in operation.

In the United States, two such bridges were built. The first was the Aerial Bridge built in Duluth, Minnesota in 1905, although the city had originally planned to build a vertical lift bridge at the site. The transporter design was used for about 25 years before the structure was reconfigured to lift a central span in 1930. The second American transporter bridge was different from other designs and partially resembled gondola lifts used in mountainous regions. The Sky Ride was part of the 1933–34 Chicago World's Fair, it was taken down after standing for just two years. However, it was the longest bridge of this type ever built at the time.

Two historic transporter bridges survived in Germany. A unique example is the bridge at Rendsburg, from 1913 which is two bridges in one: A railroad link crosses high above on the top span, and the suspended ferry carries traffic on the valley floor. The bridge at Osten is four years older and was the first transporter bridge in Germany.

The Soviet Union built the longest known transporter bridge in Stalingrad (now Volgograd) in 1955.

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Undated image of the Middlesbrough Transporter Bridge. Photo credit

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Undated image of the Middlesbrough Transporter Bridge. Photo credit

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Middlesbrough Transporter Bridge Opening. The Transporter Bridge opened on the 17th October 1911. HRH Prince Arthur of Connaught was the guest of honour for the opening ceremony of the bridge. Photo credit

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Middlesbrough Transporter Bridge Photo credit

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Middlesbrough Transporter Bridge Photo credit

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Middlesbrough Transporter Bridge Photo credit

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Middlesbrough Transporter Bridge Photo credit

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Middlesbrough Transporter Bridge Photo credit

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The world’s first transporter bridge Vizcaya Bridge in Bilbao, Spain. Photo credit

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Rendsburg High Bridge, Germany. Photo credit

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Newport transporter bridge, the U.K. Photo credit

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Newport transporter bridge, the U.K. Photo credit

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The Aerial Bridge built in Duluth, Minnesota, circa 1908. Photo credit

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The Aerial Bridge built in Duluth, Minnesota, circa 1908. Photo credit

Sources: Wikipedia, NTLWorld

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