Bridges span both space and spirit

In 1856 Walt Whitman looked down Fulton Street, in Brooklyn, to the ferry house thronged with passengers making the journey – or attempting to make the journey, for sometimes in winter the East River could be frozen solid for days – from Brooklyn to Manhattan and back. Where some might have seen the huddled masses of the new machine age, a landscape devoured by industry, the light in Whitman’s eye was very different. "Gorgeous clouds of the sunset! drench with your splendour me, or the men and women generations after me!/ Cross from shore to shore, countless crowds of passengers!/ Stand up, tall masts of Mannahatta! stand up, beautiful hills of Brooklyn!/ Throb, baffled and curious brain! throw out questions and answers!/ Suspend here and everywhere, eternal float of solution!"

And the solution was suspension. The Brooklyn Bridge was begun in 1869: the German-born engineer John Roebling built towers of stone and threw cables of steel across the turbulent tidal strait that separates Brooklyn and Manhattan; Roebling was perhaps the greatest of bridge engineers in an age that saw great, swift developments in humankind’s ability to leave his boat tied to the shore and cross rivers and gorges on foot, by carriage, by car or by train. "The earth to be spanned, connected by network," Whitman wrote two years later. The beauty of Roebling’s great bridge was no accident; he too believed that a span between shores could span the distance between those who crossed it.

Not every poet believed in the benefits of modern technology; Wordsworth invited readers to share his scorn in his poem, On The Projected Kendal and Windermere Railway, due to thunder through his beloved Lakes: "Hear ye that Whistle?/ As her long-linked Train/ Swept onwards, did the vision cross your view?/ Yes, ye were startled; – and in balance true,/ Weighing the mischief and the promised gain,/ Mountains, and Vales, and Floods, I call on you/ To share the passion of a just disdain." In our day Simon Armitage redressed the balance, striding across the Humber Bridge, versifying as he went.

Pour oil on troubled waters, after all, and what you’ve got is a mess; build a bridge and you’re much better off. The Pope brings together believers in the Roman Catholic faith all around the world:

and so he is the pontiff, from pontifex, a builder of bridges. A bridge is a visible symbol of unity; not so the tunnel which, no less an engineering feat, hides its light under a mountain or a river or even, now, the English Channel.

The building of a bridge usually takes years of human effort and is often attended by disaster – even today when, it might be imagined, the hazards of constructing such great structures might be better understood. In the 1870s, down in the compressed-air atmosphere beneath the towers of Roebling’s East River Bridge, and in St Louis, Missouri – where James Buchanan Eads was attempting to span the Mississippi – men collapsed and died from what was called "caisson disease", after the great wooden structures on top of which the stone towers were piled. Now it is better known as the bends, its cause the release of nitrogen into the blood. It is easily prevented by slow decompression, but that was not then understood.

Bridge-building, then, was a hazardous exercise: the rate of failure in the mid-to-late 19th century was one in four. William McGonagall, who commemorated the Tay Bridge disaster of 1878, could have written bridge-collapse poems alone and made a fine living.

But bridges still fall, during and after their construction. Twelve men were killed one day in 1937 when a scaffold on the half-built Golden Gate Bridge in San Francisco gave way; in 1983 a 100ft-long section of the Connecticut Turnpike, near Greenwich, collapsed; four vehicles plunged 70 ft to the banks of the Mianus River and three people were killed. Luckily the accident happened in the early hours of the morning; that stretch of road carries 100,000 vehicles a day. Seven workers were killed in June 1998 during the building of the Kurushima Crossing in southern Japan.

And yet still the engineers are driven – and rightly so – to higher towers, longer spans, new technology. Some 1,900 years ago the Emperor Trajan stretched a bridge 170 ft across the Danube. Now the Akashi Kaikyo Bridge, linking Honshu Island to Shikoku Island in Japan, spans 6,529 ft. Bridges are markers: it is quite right that the turn of the millennium will see a new bridge across the Thames.

Great bridges deserve to have great books written about them; David Bennett’s The Creation of Bridges  is not one of these, though it does have pretty pictures. Bennett is a chartered civil engineer in London; I hope he is more careful with his blueprints than he is with his proofreading. Here we read that the Brooklyn Bridge opened in 1874, yet two pages later it is still being constructed in 1876; James Eads gains an extra "e" in his name and at one point (while narrating the collapse of the Sunshine Skyway in Florida in 1986) the captain of the ship that rammed the bridge calls for engines "full Eastern!".

Still, a glance at the book might cause you to find your nearest span and wander across; it doesn’t matter if it’s by Roebling, or Telford or Ammann – who built the George Washington and Verrazano Narrows Bridges. A little crossing over a stream will do. You are suspended in the air, above the water, like magic. You rise above the waves, your feet are never wet, you go exactly where you please.

"It so happens that the work which is likely to be our most durable monument," wrote Montgomery Schuyler at the opening of the Brooklyn Bridge in 1883, "and to convey some knowledge of us to the most remote posterity, is a work of bare utility; not a shrine, not a fortress, not a palace, but a bridge."