How the moving walkway nearly overtook the Metro

Paul Collins, New Scientist 6 Aug 09;

When Paris hosted the Exposition Universelle in 1900, it unveiled its vision for the future of transport. Below ground, the city's stylish new Metro made its debut, while above ground was something more avant garde. The trottoir roulant was a moving walkway that circled the fair in a 3-kilometre loop, its articulated wooden segments "gliding around like a wooden serpent with its tail in its mouth", according to one reporter. Nearly 7 million visitors hopped on. A few even brought folding chairs, which proved useful when one woman gave birth in transit. Her child was promptly christened Trottoir Roulant Benost. A new kind of traveller had been born.

BY 1902, New Yorkers had finally had enough of the rush-hour crush on the Brooklyn Bridge. Mass transit lines converged at both sides of the East river, disgorging thousands of travellers onto already packed streetcars or teeming sidewalks. It was a "daily torture", wrote one disgruntled commuter. For Bridge Commissioner Gustav Lindenthal there was an obvious solution: a high-speed moving walkway across the bridge.

The first moving walkway had been unveiled eight years earlier at the Chicago World's Fair and had proved a huge success at subsequent expositions in Berlin and Paris. Chicago's walkway, the brainchild of engineer Max Schmidt, consisted of three rings, the first stationary, the second moving at 4 kilometres per hour and the third at 8 km/h, an arrangement that allowed walkers to adjust to each speed before moving to the next.

With the Brooklyn Bridge walkway, Schmidt upped the ante. This time he envisaged a loop system at each end of the bridge, with a series of four ever-faster walkways. Passengers moved from one to another until finally taking a seat on the benches aboard the fastest, which whisked them across the bridge at 16 km/h. Because the system ran constantly, there would be no waiting and little momentum lost on stops and starts.

In fact, the idea of high-speed walkways had been established in New York longer than anywhere else. Back in 1871, local wine merchant Alfred Speer patented the first "endless-travelling sidewalk", and promptly proposed an ambitious elevated moving walkway along Broadway. It would have zipped pedestrians along at up to 30 km/h, a prospect with comic possibilities that delighted pundits. One newspaper suggested that getting trapped with interminable bores would be a thing of the past: one "has only to suddenly step on the passing sidewalk to be carried rapidly beyond sight or hearing of his tormentor". Despite building a working model and lobbying state and city politicians for a decade, Speer discovered his invention was simply too visionary to find a backer.

Thirty years on, the idea of a moving walkway across the East river had more chance of finding favour. Equipped with posts to hold on to and benches along the fastest ring, the walkways had proved remarkably safe. "A record of 12,000,000 passengers of both sexes and all ages carried in Paris, Berlin, and Chicago without accident, tends to dispel any grave anxiety on this score," declared The New York Times.

Although details about lighting and shelter from the weather were still to be worked out, Lindenthal approved the proposed walkway - only to have his recommendation quietly and inexplicably excised from the public record by New York's mayor, Seth Low. Many years later, the suspicion arose that a rival company, Brooklyn Rapid Transit, probably had a hand in burying the idea. BRT, which had a near-monopoly on the borough's public transport system, would have taken a dim view of other technologies or operators on its turf.

Undaunted, Schmidt proposed a flurry of similar projects around Manhattan - running down Broadway, along Wall Street, over the Williamsburg Bridge and across 23rd and 34th Street. To Schmidt, the advantages of the moving walkway were so compelling that he was convinced they would supplant some subways rather than supplement them. By 1909, he was pushing a massive $70 million scheme that would provide Manhattan with a network of subterranean moving sidewalks.

So why aren't there any walkways sliding past the Stock Exchange or beneath the Empire State Building? "That is the question I have struggled with," says Lee Gray, a historian of moving sidewalks at the University of North Carolina in Charlotte. "But there was the political clout of companies pushing subways - and their familiarity. Everybody gets what a train is, whether it's above ground or below ground."

New York was left pondering whether to install a more modest moving sidewalk between Times Square and Grand Central Station. But by the 1920s, the bug had bitten other cities: underground walkways were considered for Atlanta, Boston, Los Angeles and even car-crazy Detroit, where they would have sped along at a heady 40 km/h. Even the nation's capital pondered the possibility of propelling politicians along an underground walkway from their offices to Capitol Hill.

Not surprisingly, science fiction writers were very taken with the idea. H. G. Wells was a fan, and Robert Heinlein, in his 1940 short story The Roads Must Roll, envisioned interstate passenger platforms moving at speeds of up to 160 km/h. Others were more bemused: in the midst of Schmidt's crusade in Manhattan, the New York Tribune called for "a moving sidewalk from Texas to New York to bring up cotton and those cheap winter strawberries", while another newspaper jokingly suggested that city buildings be placed on moving walkways so that people could simply stand around and wait for the right one to arrive.

The future, though, is where all these proposals remained. Despite their advantages, the novelty of moving sidewalks counted against them. So did the spectre of crippling breakdowns. Unlike an out-of-service subway car, a broken-down section of sidewalk could not simply be shunted aside. Parisians had also discovered that one disadvantage of trains - that they don't run constantly - could be a blessing. An otherwise admiring account of the trottoir roulant noted that it made a non-stop racket that alternated between "the din made by the lids of twenty million Brobdingnagian kettles" and "a high pitched, fierce iron screech".

It took another half a century and the development of quieter, rubber-covered surfaces by the Goodyear Tire Company for moving walkways to make a comeback. Most appeared at increasingly sprawling airports, but railways weren't immune to their charms either. In 1960, 57 years after it was first proposed, the Travelator opened at London's Bank underground station. Even the notion of moving sidewalks to the US House of Representatives and to Times Square awoke from decades of slumber, leaving The New York Times to innocently wonder "why this improvement was not considered when this present [subway] system... was built".

These new walkways, however, were essentially a single conveyor moving from A to B, far simpler than the earlier many-ringed, multispeed systems with multiple points of entry and exit. The modern moving walkway is not a transport system in its own right, more a minor supplement to other forms of transit. Its most ambitious use in modern times came in 1961, when the city of Tacoma in Washington built an underground "escalade" of moving sidewalks. It was boarded up in 1984 after years of urban decay and vandalism.

Paris, however, never entirely lost its dream of a trottoir roulant. Even before the 1900 expo, there had been proposals for a citywide system 17 kilometres long. It seemed fitting then that a new incarnation, the Trottoir Roulant Rapide, was unveiled at Montparnasse Metro station in 2003.

Instead of three adjacent walkways moving at different speeds, the new walkway changed speed along its length. The first section moved slowly. The long midsection rolled along at a brisk 11 km/h - and deposited passengers onto a final deceleration section in readiness for their return to terra firma. Dogged by design and reliability issues, it was taken out of service in May this year, with the French magazine Rue 89 delivering the stinging verdict that those who had promoted it "sold this toy as a flagship of French technology". But a century ago, the trottoir roulant was no toy. It was, for a brief time, a brisk stroll into the future.