The Great Belt Bridge or Great Belt fixed link is a multi-element fixed link crossing the Great Belt strait between the Danish islands of Zealand and Funen. It consists of a road suspension bridge and a railway tunnel between Zealand and the small island Sprogø in the middle of the Great Belt, and a box-girder bridge for both road and rail traffic between Sprogø and Funen. The total length is 18 kilometres (11 mi).
A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is enclosed except for the portals, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.
The Hong Kong–Zhuhai–Macau Bridge (HZMB) is a 55-kilometre (34 mi) bridge–tunnel system consisting of a series of three cable-stayed bridges, an undersea tunnel, and four artificial islands. It is both the longest sea crossing and the longest open-sea fixed link in the world. The HZMB spans the Lingding and Jiuzhou channels, connecting Hong Kong and Macau with Zhuhai— a major city on the Pearl River Delta in China.
The Sydney Harbour Tunnel is a twin-tube road tunnel in Sydney, Australia. The tunnel was completed and opened to traffic in August 1992 to provide a second vehicular crossing of Sydney Harbour to alleviate congestion on the Sydney Harbour Bridge. It is one of two transportation tunnels under the harbour, the other being a set of rail tunnels for the Sydney Metro.
Marmaray is a 76.6-kilometre-long (47.6 mi) commuter rail line located in Istanbul, Turkey. The line runs from Halkalı, on the European side, to Gebze, on the Asian side, along the north shore of the Sea of Marmara. Mostly using the right-of-way of two existing commuter rail lines, the Marmaray line linked the two lines via a tunnel under the Bosporus strait, becoming the first standard gauge rail connection between Europe and Asia. The two existing sections of the line were rebuilt and expanded from two-tracks to three-tracks, to allow for higher capacity with intercity and freight rail. The name Marmaray is a portmanteau of the words Marmara and Ray, which is Turkish for rail.
The Jack Lynch Tunnel is an immersed tube tunnel and an integral part of the N40 road network in Cork, Ireland. It is named after former Taoiseach, Jack Lynch, a native of Cork.
The Strait of Gibraltar crossing is a hypothetical bridge or tunnel spanning the Strait of Gibraltar that would connect Europe and Africa. The governments of Spain and Morocco appointed a joint committee to investigate the feasibility of linking the two continents in 1979, which resulted in the much broader Euromed Transport project.
The Fehmarn Belt fixed link or Fehmarn Belt tunnel is an under-construction immersed tunnel, which will connect the Danish island of Lolland with the German island of Fehmarn, crossing the 18-kilometre-wide (11 mi) Fehmarn Belt in the Baltic Sea.
The Posey and Webster Street Tubes are two parallel underwater tunnels connecting the cities of Oakland and Alameda, California, running beneath the Oakland Estuary. Both are immersed tubes, constructed by sinking precast concrete segments to a trench in the Estuary floor, then sealing them together to create a tunnel. The Posey Tube, completed in 1928, currently carries one-way (Oakland-bound) traffic under the Estuary, while the Webster Street Tube, completed in 1963, carries traffic from Oakland to Alameda.
A submerged floating tunnel (SFT), also known as submerged floating tube bridge (SFTB), suspended tunnel, or Archimedes bridge, is a proposed design for a tunnel that floats in water, supported by its buoyancy.
An underwater tunnel is a tunnel which is partly or wholly constructed under the sea or a river. They are often used where building a bridge or operating a ferry link is unviable, or to provide competition or relief for existing bridges or ferry links. While short tunnels are often road tunnels which may admit motorized traffic, unmotorized traffic or both, concerns with ventilation lead to the longest tunnels being electrified rail tunnels.
A fixed link or fixed crossing is a permanent, unbroken road or rail connection across water that uses some combination of bridges, tunnels, and causeways and does not involve intermittent connections such as drawbridges or ferries. A bridge–tunnel combination is commonly used for major fixed links.
There are a number of proposed fixed connections—road or rail, bridge or tunnel—designed to connect the islands of Ireland and Great Britain, connect the island of Great Britain to mainland Europe, as well as to build other connections amongst the smaller islands in the British Islands.
China Road and Bridge Corporation (CRBC), a subsidiary of Fortune Global 500 company China Communications Construction Company (CCCC), focuses on global civil engineering and construction projects such as highways, railways, bridges, ports, and tunnels. Growing out of the Foreign Aid Office of the Ministry of Communications of China, CRBC and its predecessors have been executing projects since 1958. In 1979, CRBC was formally established and entered the international contracting market. The parent entity, CCCC, was formed through the combination of CRBC and China Harbour Engineering Company Ltd (CHEC) in 2005.
The Busan–Geoje Fixed Link or Geoga Bridge is an 8.2-kilometer (5.1-mi) bridge-tunnel fixed link that connects the South Korean city of Busan to Geoje Island. The route opened on December 13, 2010 and shortens the travelling distance between Geoje Island and Busan by about 60 kilometers (37 mi). The new road has two lanes in each direction and carries National Road 58.
The Marmaray Tunnel is a 13.5 km (8.4 mi) long undersea railway tunnel in Istanbul, Turkey, beneath the Bosporus strait, linking Kazlıçeşme, Zeytinburnu in Europe with Ayrılıkçeşmesi in Asia. The tunnel consists of two single track tunnels with three underground railway stations: Yenikapı, Sirkeci and Üsküdar.
Femern A/S is a Danish planning company charged with preparing the Fehmarnbelt Tunnel across the Baltic Sea between the Danish island of Lolland and the German island of Fehmarn. Construction of the 18 km immersed tunnel, which is expected to be completed by 2029, will comprise a dual-track railway and a four-lane motorway. Femern A/S is in charge of planning and providing the basis for regulatory approval of the project on behalf of the Danish government. The framework for this work falls under a treaty between Denmark and Germany which was signed in 2008. The planned tunnel, together with upgrades to the surrounding infrastructure, will reduce travel times between Northern Germany and Scandinavia.
The 1915 Çanakkale Bridge is a road suspension bridge in the province of Çanakkale in northwestern Turkey. Situated just south of the coastal towns of Lapseki and Gelibolu, the bridge spans the Dardanelles, about 10 km (6.2 mi) south of the Sea of Marmara. The bridge was officially opened by President Recep Tayyip Erdoğan on 18 March 2022 after roughly five years of construction. The year "1915" in the official Turkish name honours an important Ottoman naval victory against the navies of the United Kingdom and France during World War I.
Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management. Tunnel construction is a subset of underground construction.
The Tuen Mun–Chek Lap Kok Link is a road project in the New Territories, Hong Kong. It comprises two elements: the "Northern Connection" and the "Southern Connection". The Northern Connection comprises an undersea tunnel crossing the Urmston Road, linking Tuen Mun to the "Boundary Crossing Facilities" (BCF), an artificial peninsula connected to Hong Kong International Airport. The Southern Connection, officially named Shun Long Road (順朗路), comprises viaducts linking the BCF to North Lantau Highway on Lantau Island.
