Chesapeake Bay Bridge–Tunnel

Listen first. Tires hum on concrete, a steady rhythm under the wheels. On both sides there is open water, grey-green or bright blue depending on the sky. The salt wind pushes against the car. Ahead, the road runs low and straight across the bay until it seems to stop at the horizon. This is the Chesapeake Bay Bridge–Tunnel, and for the next stretch of your journey you are driving across the sea.

The crossing links two very different parts of Virginia. Behind you, or ahead of you, depending on your direction, is Virginia Beach and the busy Hampton Roads region. On the far side is the Eastern Shore, a long, quiet strip of farmland, marsh and small towns. Shore to shore, the crossing covers roughly 28 kilometres, about seventeen and a half miles. Including the approach roads, it runs to around twenty-three miles.

Before this road existed, the trip across the mouth of the bay depended on ferries. Travellers waited at the docks, watched the weather, and hoped for a smooth passage. A fixed crossing changed that. When the bridge–tunnel opened in 1964, the Eastern Shore was suddenly a short drive from the cities to the south. Farms, fishing towns and travellers on the coastal route up the East Coast all felt the difference.

Here is the first surprise. The road does not stay on the surface the whole way. Twice, it dives under the water. Engineers faced a hard problem. Some of the busiest shipping lanes in the country pass through this stretch of the bay. These lanes lead to the ports of Hampton Roads and to one of the world's largest naval bases. A normal bridge would need to be extremely tall to clear warships and cargo vessels.

So the designers chose a mix of approaches. Most of the crossing is low trestle, a long line of concrete spans resting on piles driven into the bay floor. Over the two main shipping channels, the road drops into tunnels, each roughly a mile long. Ships pass freely overhead, with nothing above them but open sky. Over smaller channels, the road climbs onto higher bridges instead, and the view widens as you rise.

To make the tunnels work, the builders needed somewhere for the road to go underground. Their answer was to build islands. There are four man-made islands along the route, created from rock and sand in open water. Each tunnel starts on one island and ends on another. As you drive, watch for the moment the road curves onto a patch of rock and pavement in the middle of the bay. Then the tunnel mouth appears, and the daylight disappears behind you.

Inside, the tunnel is close and bright. The sound changes at once. The wind noise stops, and the hum of the engine bounces off the tiled walls. Somewhere above your roof, there is water, and perhaps a ship moving through it. Few drivers think about this while they are inside. But it is worth a moment of attention. You are travelling along the floor of a major shipping channel.

The project won wide attention in its time. Soon after it opened, an engineering competition named it one of the seven engineering wonders of the modern world. That praise came from the scale of the work and the conditions. Crews built it in open water, exposed to Atlantic storms, strong currents and winter weather. Today, the original structure sits beside a parallel trestle that was added in the late 1990s, so traffic in each direction has its own span.

The work did not end there. In recent years, a new parallel tunnel has been under construction at the Thimble Shoal Channel, the southern channel closer to Virginia Beach. If you see cranes, barges and work equipment near the first island, this is the reason. The aim is to give each direction of traffic its own tunnel. It is a reminder that a crossing like this is never really finished. It is maintained, repaired and expanded, year after year.

Now look at the water around you. The bay here is where the Chesapeake meets the Atlantic Ocean. Fresh water from many rivers mixes with salt water from the sea. The concrete piles under the trestle work almost like a reef. They attract fish, and fish attract people. For many years, anglers have treated the crossing as a favourite spot. Boats often gather near the islands and along the trestle, especially in warmer months.

The birds have noticed too. The rocky islands give seabirds a place to rest far from shore. In colder months, the area becomes a well-known destination for birdwatchers, who look for ducks, gulls, loons and other sea birds that arrive on the winter winds. Even from a moving car, you may see birds lined up on railings or diving into the waves. Watch the rocks at the edges of the islands.

On a clear day, the size of the place becomes easier to understand. Large container ships move slowly toward port. Grey navy vessels sometimes pass, heading for the base at Norfolk. Far away, the low line of land on each shore can almost vanish into haze. On a stormy day, the scene is very different. Waves break against the islands, and spray can reach the road. Strong winds sometimes lead the operators to restrict tall vehicles, or to close the crossing entirely.

As you reach the far shore, notice how quickly the open water gives way to land again. Marsh grass, pine trees and a quieter road take over. The bay stays behind you, wide and moving, with the trestle running back across it in a thin grey line. Take one last look in the mirror if it is safe. You have just crossed one of the great working waterways of America, partly above it, and partly beneath it.