How is an immersed tunnel built?

Immersed tunnels consist of very large precast concrete or concrete-filled steel tunnel elements fabricated in dry docks and then installed underwater. Once they reach their final location, the elements are immersed, lowered into a prepared trench, and joined to previously placed tunnel elements.

What is the use of an immersed tube tunnel?

An immersed tube (or immersed tunnel) is a kind of undersea tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuaries and sea channels/harbours.

How do they make tunnel under water?

To use this method, builders dig a trench in the riverbed or ocean floor. They then sink pre-made steel or concrete tubes in the trench. After the tubes are covered with a thick layer of rock, workers connect the sections of tubes and pump out any remaining water.

Why do they build tunnels underwater?

An undersea tunnel is a tunnel which is partly or wholly constructed under the sea or an estuary. 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.

What kind of tunnel is an immersed tube?

The immersed tunnel, also called Sunken Tube, is a tunnel construction method commonly used for crossing a body of shallow water. The method has been widely used for about 100 years, and more than 150 immersed tunnels have been constructed worldwide. They mainly serve as road or rail tunnels,…

How are the elements of the immersed tube prepared?

The tunnel is made up of separate elements, each prefabricated in a manageable length, then having the ends sealed with bulkheads so they can be floated. At the same time, the corresponding parts of the path of the tunnel are prepared, with a trench on the bottom of the channel being dredged and graded to fine tolerances to support the elements.

How to build an immersed tube rail system?

Immersed Tube Tunnel 1 Constructing the casting basin for fabrication the tunnel elements 2 Constructing the first batch of tunnel elements 3 Construct the temporary water ballast system 4 Seal the element with a temporary bulkhead 5 Fill the casting basin (inundation) 6 Remove the basin gate

Who was the inventor of the immersed tube?

Immersed tube, also called Sunken Tube, technique of underwater tunneling used principally for underwater crossings. The method was pioneered by the American engineer W.J. Wilgus in the Detroit River in 1903 for the Michigan Central Railroad.