Intercontinental and transoceanic fixed links

Permanent bridges, tunnels, or causeways cross a sea or ocean strait to connect separated landmasses. They carry transport without relying on a vessel for each crossing.

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Immersed tube tunnel: A tunnel made from prefabricated sections placed in a dredged seabed trench and joined underwater. This construction method creates submerged road and rail crossings where deep boring is unsuitable.
Channel Tunnel: A rail tunnel beneath the English Channel connecting Folkestone in England with Coquelles in France. It is a major undersea rail link between Britain and continental Europe.
Bering Strait crossing: A proposed bridge or tunnel across the Bering Strait between Alaska and Russia’s Chukotka region. It illustrates the challenge of a transcontinental crossing with extreme climate and limited approaches.
Induced demand: The increase in travel that occurs when transport capacity or convenience improves. A new crossing can generate traffic beyond the journeys it initially appears to accommodate.
Submerged floating tunnel: A buoyancy-supported tunnel suspended below the water surface and anchored to the seabed or shore. It is a proposed option for deep fjords and other crossings difficult for conventional tunnels.
Øresund Bridge: A combined road and rail crossing linking Copenhagen, Denmark, with Malmö, Sweden. Its bridge, artificial island, and tunnel form one continuous crossing between two countries.
Gibraltar Strait crossing: A proposed fixed link across the Strait of Gibraltar between Europe and Africa. Deep water and difficult geology complicate a link between two continents.
Travel time: The duration required to move between places by a particular route and mode. Shorter, more predictable journeys are among the main claimed benefits of fixed links.
Suspension bridge: A bridge whose deck hangs from vertical suspenders attached to main cables supported by towers. Its long spans can cross wide channels while keeping the structure above shipping lanes.
Seikan Tunnel: A railway tunnel beneath the Tsugaru Strait connecting Japan’s islands of Honshu and Hokkaido. It demonstrates a long undersea rail connection built through a seismically active region.