Bronx–Whitestone Bridge

Stand near the water's edge and listen. Traffic on the deck above makes a steady, low hum that never fully stops. Below it, small waves slap against the rocks. Gulls cry over the water. Look up, and two pale steel towers rise from the river. Between them, a long, thin roadway seems to float in the air. This is the Bronx–Whitestone Bridge, and it is lighter and plainer than almost any big bridge you have seen.

The bridge crosses the East River at a wide point near where the river opens into Long Island Sound. On the north side is the Bronx, near the neighbourhood of Throggs Neck and the green slope of Ferry Point Park. On the south side is Whitestone, a quiet residential corner of Queens. For most New Yorkers, the bridge is simply a road to the airports, or to Long Island. But it has one of the most interesting engineering stories in the city.

The bridge opened in 1939. The timing was not an accident. That spring, the New York World's Fair opened in Flushing Meadows, in Queens, only a short drive away. Planners wanted a fast new road from the Bronx and New England straight to the fairgrounds. The bridge was finished in a remarkably short time, and cars were crossing it just before the fair welcomed its first visitors.

The project belonged to Robert Moses, the powerful planner who shaped much of modern New York. Moses built highways, parks, beaches and bridges across the city, and he controlled the authority that paid for them through tolls. Love him or criticise him, his roads still carry millions of people every year. This bridge was one piece of his larger plan to link the boroughs with fast, wide parkways.

The engineer was Othmar Ammann, a Swiss-born designer who also gave New York the George Washington Bridge and, much later, the Verrazzano-Narrows Bridge. Ammann believed a great bridge should look simple. Here, he and his architectural partners chose clean lines and very little decoration. Look at the towers. There is no heavy cross-bracing between them above the road, and no carved stone. The style is often called Art Moderne — a smooth, streamlined version of Art Deco popular in the 1930s.

Now comes the first surprise. When it opened, the roadway was supported by shallow steel girders, much thinner than the deep trusses used on older bridges. This made the deck look elegant, almost like a ribbon. But a thin deck can move in the wind. And in 1940, just one year after this bridge opened, a bridge with a similar slender design collapsed across the country.

That bridge was the Tacoma Narrows Bridge, in Washington State. Strong winds made its deck twist and roll until it broke apart. Film of the collapse shocked engineers everywhere. Nobody had fully understood how wind could shake a long, light bridge. Drivers on the Whitestone had already noticed that its own deck could move in strong winds. Suddenly, that movement looked like a serious warning.

So the bridge was changed. In the 1940s, engineers added tall steel trusses along the sides of the deck to make it stiffer. They also added extra weight and changed the cables. The trusses did their job, but they made the bridge look heavier and boxier. For decades, the slender design that Ammann wanted was hidden behind a wall of steel.

Here is the second surprise. In the early 2000s, engineers took those trusses away. By then, wind-tunnel testing and computer modelling were far more advanced. Instead of stiff trusses, they fitted the deck edges with angled fairings — smooth, wedge-shaped panels made of fibreglass. These panels guide the wind around the deck, a little like the shape of an aircraft wing. Today the bridge again looks close to its original, thin profile.

The bridge also changed for people on foot. When it opened, it had walkways for pedestrians. During the wartime and later rebuilding, those walkways gave way to more space for cars. Today there is no public path across the bridge. It belongs to vehicles only. That makes the parks at each end the best places to experience it at a human pace.

On the Queens side, Francis Lewis Park sits almost directly under the southern approach. It is a small, sloping lawn with views straight up into the underside of the deck. On the Bronx side, Ferry Point Park spreads along the shore, with open ground and a long waterfront. From either spot, you can follow the curve of the main cables as they dip between the towers and rise again toward the land.

Look east along the water, and you may see a second suspension bridge in the distance. That is the Throgs Neck Bridge, opened in 1961. The two bridges now share the work of carrying traffic between the Bronx and Queens. Together they mark the place where the East River ends and the open Sound begins. Ships, tugboats and small pleasure boats pass between them, so the view keeps changing through the day.

The name of the Queens neighbourhood has its own story. Locals say that Whitestone takes its name from a large white boulder that once stood near the shoreline here, a landmark for boats. Whether every detail of that tale is true is hard to say, but the name has outlived the rock. Today the neighbourhood is mostly quiet streets and family homes, a short walk from one of the busiest roads in the city.

Before you leave, look up one more time. Notice how thin the deck looks against the sky, and how the cables hold the whole road with what seems like little effort. Listen to the hum of the traffic, and the water moving underneath. Every car crossing above you rides on an idea from the 1930s, corrected after a famous failure, and improved again in our own century. Take that thought with you as you walk back toward the streets.