What is the longest continuous underwater tunnel in North America?
At 9,117 feet the Brooklyn Battery Tunnel is the longest continuous underwater vehicular tunnel in North America.
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The Brooklyn-Battery Tunnel cost $90 million to build, and is still the longest continuous underwater vehicular tunnel in the world, measuring 9,117 ft. in length.
The Laerdal Tunnel in western Norway is the longest road tunnel in the world. It takes about 20 minutes to pass through the tunnel. Brightly colored lights placed every six kilometers help drivers stay alert.
The Chesapeake Bay Bridge–Tunnel (CBBT, officially the Lucius J. Kellam Jr. Bridge–Tunnel) is a 17.6-mile (28.3 km) bridge–tunnel that crosses the mouth of the Chesapeake Bay between Delmarva and Hampton Roads in the U.S. state of Virginia. It opened in 1964, replacing ferries that had operated since the 1930s.
The Seikan Tunnel (Japanese: ??????, Seikan Tonneru or ????, Seikan Zuido) is a 53.85 km (33.46 mi) dual-gauge railway tunnel in Japan, with a 23.3 km (14.5 mi) portion under the seabed of the Tsugaru Strait, which separates Aomori Prefecture on the main Japanese island of Honshu from the northern island of Hokkaido.
The Howard Tunnel is located near Seven Valleys, Pennsylvania. In operation since 1838, it is the second oldest active rail tunnel in the U.S. Originally constructed by the York and Maryland Line Rail Road, it formed a critical link in the north-south line assembled by the Northern Central Railway.
Seikan Tunnel, JapanConstruction of the Seikan tunnel experienced many technical challenges as the infrastructure sits through an earthquake-prone zone. The engineers couldn't use tunnel boring machines (TBM) as the rock and soil underneath the Tsugaru Strait was arbitrarily unpredictable.
“Its skeletal structure is made up of hundreds of massive 21-ton iron rings that were bolted together. In addition, the interior of the rings is encased in concrete, thereby sealing out the Hudson River.”
Designed by Ole Singstad, the tunnel was built by shield-and-compressed-air methods to hold back the outside water pressure. The tunnel consists of three vehicular tubes, each of which carries two lanes of traffic. It is about 1.5 miles (2.4 km) long and lies 97 feet (30 metres) below the river's surface.
It is part of the Norwegian National Road 13 running between Stavanger and Ryfylke (district) under the Horgefjord (part of the Boknafjord). The tunnel is part of the Ryfast project. It is 14.4 kilometres (8.9 mi) long and is currently the world's longest subsea road tunnel, and the deepest tunnel of any kind.