Bridge-tunnel
Encyclopedia
Road
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
or rail connection across water that uses some combination of bridge
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
s, tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...
s, and causeway
Causeway
In modern usage, a causeway is a road or railway elevated, usually across a broad body of water or wetland.- Etymology :When first used, the word appeared in a form such as “causey way” making clear its derivation from the earlier form “causey”. This word seems to have come from the same source by...
s and does not involve intermittent connections such as drawbridge
Drawbridge
A drawbridge is a type of movable bridge typically associated with the entrance of a castle surrounded by a moat. The term is often used to describe all different types of movable bridges, like bascule bridges and lift bridges.-Castle drawbridges:...
s or ferries
Ferry
A ferry is a form of transportation, usually a boat, but sometimes a ship, used to carry primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate on regular, frequent, return services...
.
The Confederation Bridge
Confederation Bridge
The Confederation Bridge is a bridge spanning the Abegweit Passage of Northumberland Strait, linking Prince Edward Island with mainland New Brunswick, Canada. It was commonly referred to as the "Fixed Link" by residents of Prince Edward Island prior to its official naming. Construction took place...
was commonly referred to as "The Fixed Link" by residents of New Brunswick and Prince Edward Island prior to its official naming.
Bridge-tunnels
For water crossings, a tunnel is generally more costly to construct than a bridge. However, navigational considerations at some locations may limit the use of high bridges or drawbridgeDrawbridge
A drawbridge is a type of movable bridge typically associated with the entrance of a castle surrounded by a moat. The term is often used to describe all different types of movable bridges, like bascule bridges and lift bridges.-Castle drawbridges:...
spans when crossing shipping channels, necessitating the use of a tunnel. Examples of such tunnels include the Elizabeth River
Elizabeth River (Virginia)
The Elizabeth River is a tidal estuary forming an arm of Hampton Roads harbor at the southern end of Chesapeake Bay in southeast Virginia in the United States. It is located along the southern side of the mouth of the James River, between the cities of Portsmouth and Norfolk...
tunnels, in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, between Norfolk
Norfolk, Virginia
Norfolk is an independent city in the Commonwealth of Virginia in the United States. With a population of 242,803 as of the 2010 Census, it is Virginia's second-largest city behind neighboring Virginia Beach....
and Portsmouth, Virginia
Portsmouth, Virginia
Portsmouth is located in the Hampton Roads metropolitan area of the U.S. Commonwealth of Virginia. As of 2010, the city had a total population of 95,535.The Norfolk Naval Shipyard, often called the Norfolk Navy Yard, is a historic and active U.S...
and the George Massey Tunnel
George Massey Tunnel
The George Massey Tunnel is a highway traffic tunnel in the Metro Vancouver region of southwestern British Columbia. It is located approximately 20 km south of the city centre of Vancouver, British Columbia, and approximately 30 km north of the Canada-U.S...
in Greater Vancouver
Greater Vancouver
Greater Vancouver is the metropolitan area centred on the city of Vancouver, British Columbia, Canada, roughly coterminous with the Greater Vancouver Regional District, which is governed by a body known as Metro Vancouver...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
In other instances, when longer distances are involved, a combination of bridges and tunnels may be less costly and easier to ventilate than a single, lengthy tunnel. This situation may occur when more economical drawbridges are not allowed for one reason or another. For example, in the American state
American state
American state may refer to:*U.S. state*United States of America*Organization of American States...
of Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
, such crossings include the Hampton Roads Bridge-Tunnel
Hampton Roads Bridge-Tunnel
The Hampton Roads Bridge-Tunnel is the -long Hampton Roads crossing for Interstate 64 and U.S. Route 60. It is a four-lane facility comprising bridges, trestles, man-made islands, and tunnels under the main shipping channels for Hampton Roads harbor in the southeastern portion of Virginia in the...
and the Monitor-Merrimac Memorial Bridge-Tunnel
Monitor-Merrimac Memorial Bridge-Tunnel
Monitor-Merrimac Memorial Bridge-Tunnel is the 4.6 mile-long Hampton Roads crossing for Interstate 664 in the southeastern portion of Virginia in the United States...
, both of which cross the harbor at Hampton Roads
Hampton Roads
Hampton Roads is the name for both a body of water and the Norfolk–Virginia Beach metropolitan area which surrounds it in southeastern Virginia, United States...
, and the Chesapeake Bay Bridge-Tunnel
Chesapeake Bay Bridge-Tunnel
The Chesapeake Bay Bridge-Tunnel is a long fixed link crossing the mouth of the Chesapeake Bay and connecting the Delmarva Peninsula's Eastern Shore of Virginia with Virginia Beach and the metropolitan area of Hampton Roads, Virginia...
, a 37 km (23 mi) long structure (including approach highways) that crosses the mouth of the Chesapeake Bay
Chesapeake Bay
The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...
with a combination of bridges and tunnels across two widely separated shipping channels, using four artificial islands built in the bay as portals. Tunnels had to be used instead of drawbridges because the waterways they cross are critical to military naval operations and could not afford to be blocked off by a bridge collapse in the event of disaster or war.
Another example is the Oresund Connection, connecting Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
and Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
. It has a 7.8 km (4.8 mi) bridge, an artificial island
Artificial island
An artificial island or man-made island is an island or archipelago that has been constructed by people rather than formed by natural means...
in the middle of the Oresund
Oresund
The Sound , is the strait that separates the Danish island Zealand from the southern Swedish province of Scania. Its width is just at the narrowest point between Helsingør, Denmark, and Helsingborg, Sweden...
strait, and a 4 km (2.5 mi) tunnel nearest to Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
. A bridge could not be built there, because it would have been too close to the Copenhagen International Airport
Copenhagen Airport
Copenhagen Airport is the main international airport serving Copenhagen, Denmark and the Oresund Region. It is located on the island of Amager, south of Copenhagen city centre, and west of Malmö city centre on the other side of the Oresund Bridge. The airport lies mainly in the municipality...
.
The Tokyo Bay Aqua-Line
Tokyo Bay Aqua-Line
The , also known as the Trans-Tokyo Bay Highway, is a bridge-tunnel combination across Tokyo Bay in Japan.It connects the city of Kawasaki in Kanagawa Prefecture with the city of Kisarazu in Chiba Prefecture, and forms part of National Route 409...
is a bridge-tunnel combination across Tokyo Bay
Tokyo Bay
is a bay in the southern Kantō region of Japan. Its old name was .-Geography:Tokyo Bay is surrounded by the Bōsō Peninsula to the east and the Miura Peninsula to the west. In a narrow sense, Tokyo Bay is the area north of the straight line formed by the on the Miura Peninsula on one end and on...
in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It connects the city of Kawasaki
Kawasaki, Kanagawa
is a city located in Kanagawa Prefecture, Japan, between Tokyo and Yokohama. It is the 9th most populated city in Japan and one of the main cities forming the Greater Tokyo Area and Keihin Industrial Area....
in Kanagawa Prefecture
Kanagawa Prefecture
is a prefecture located in the southern Kantō region of Japan. The capital is Yokohama. Kanagawa is part of the Greater Tokyo Area.-History:The prefecture has some archaeological sites going back to the Jōmon period...
with the city of Kisarazu
Kisarazu, Chiba
is a city located in Chiba, Japan. As of September 2010, Kisarazu has an estimated population of 126,906 and a density of 915 persons per km². The total area was 138.73 km²....
in Chiba Prefecture
Chiba Prefecture
is a prefecture of Japan located in the Kantō region and the Greater Tokyo Area. Its capital is Chiba City.- History :Chiba Prefecture was established on June 15, 1873 with the merger of Kisarazu Prefecture and Inba Prefecture...
. With an overall length of 14 km, it includes a 4.4 km bridge and 9.6 km tunnel underneath the bay — which is the longest underwater tunnel for cars in the world. Drawbridges were impractical here because Tokyo Bay is too active a sea lane.