Chesapeake Bay Bridge-Tunnel
Toll collector at Chesapeake Bay Bridge Tunnel

Oneil Lewis, collects a toll from a motorist at the Chesapeake Bay Bridge Tunnel in Virginia Beach, Va. The structure celebrated its 40th anniversary in 2004. It is considered the world's largest bridge-tunnel complex.

AP Photo/Jason M. Hirschfeld

Two bridges span the Chesapeake Bay, a long estuary sandwiched between Virginia and Maryland. The first is the Chesapeake Bay Bridge, a dual-span, 4.32-mile- (6.95-kilometer-) long bridge that connects the eastern and western shores of Maryland. Although this bridge offers an interesting collection of designs in a single structure -- cantilever, arch and suspension -- it pales a bit when it is compared to its cousin located a few miles to the south. The official name of this second bridge is the Lucius J. Kellam, Jr. Bridge-Tunnel, more commonly known as the Chesapeake Bay Bridge-Tunnel.

As its name suggests, the link consists of a series of bridges and tunnels to span the 17 miles (27.4 kilometers) of brackish water separating Cape Charles and Virginia Beach, Virginia. The majority of the bridge-tunnel complex is above the water, supported by more than 5,000 piers. Most of these piers are relatively short, so that the bridge seems to skim just above the surface of the water. To allow ships to pass, two 1-mile- (1.6-kilometer-) long tunnels carry traffic beneath the bay's primary navigation channels. Man-made islands, each approximately 5 acres (2 hectares) in size, are located at each end of the two tunnels and act as transition points between the tunnels and bridges.

When the original bridge-tunnel complex (what is now the northbound side) opened in 1965, it won the American Society of Civil Engineers award for "Outstanding Engineering Achievement." It was also designated "One of Seven Engineering Wonders of the Modern World" in 1965. Thirty years later, engineers began construction on a second link (the southbound side), which opened to traffic in 1999.

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