When the colossal Brooklyn Bridge, linking New York’s Manhattan with Long Island, was completed in 1883, it was the engineering achievement of the century – the longest single span ever built the tallest and strongest, the first to use steel cables.
Today there are bigger bridges but they could not have been built had the Brooklyn Bridge not shown the way. Its story is still the greatest bridge building story of all. Two men, father and son, were responsible and it is a magnificent monument to their memory.
As an engineering student John A Roebling saw the first expansion bridge built in his native Germany. In 1831, aged 25, he emigrated to America and in 1842 patented the first wire rope an improvement on the hemp ropes then in use for without wire rope there could be no long hard elevators.
To demonstrate the value of this new material, Roebling built the first railway suspension bridge in the world across the Niagara Gorge which became the wonder of the age.
In the 1860’s, Brooklyn, the fastest growing city in the USA, was handicapped by lack of transportation. The trip to New York by ferry sometimes took up to two hours and the idea of a bridge had been brought up again and again.
It had been considered almost impossible, for the bridge would have to have a span of 1,600 feet and would be 130 feet above water level across the East River.
At both ends, 75 feet of mud would have to be removed to get to solid foundations. Such obstacles had never been surmounted anywhere in the world before.
In 1857, Roebling wrote to a New York newspaper outlining how it could be done. During the next two years he sent his son, Washington Roebling, to Europe to study every recent engineering development, particularly caissons, i.e., chambers in which the water was helped out by air pressure.
John Roebling died in July 1869 shortly after he had persuaded the directors of Brooklyn to entrust the greatest engineering work of the century to his son.
The young engineer’s biggest problem was laying the foundation of the great towers at the bottom of the muddy river – each foundation having to bear a weight of 88,000 tons. The caisson, an air tight box as big as a large house, was towed into place and workmen inside excavated the river bottom, sending the debris up through the shafts.