Underwater construction is industrial construction in an underwater environment. It is a part of the marine construction industry.It can involve the use of a variety of building materials, mainly concrete and steel. Underwater construction is common in the civil engineering, coastal engineering, energy, and petroleum extraction industries.
How is a bridge built over sea?With the use of coffer dam.A cofferdam is a structure that retains water and soil that allows the enclosed area to be pumped out and excavated dry. Cofferdams are commonly used for construction of bridge piers and other support structures built within water.Watch the video from Lesics:
Construction below the water table is mostly managed by using cofferdams or pressurised caissons to exclude water sufficiently to work above the local water level within the enclosure, though it may also be possible to keep the water level down by pumping it out as fast as it seeps in, thereby artificially lowering the water table at the worksite.
Bridges and causeways over bodies of water often require foundation structure below water level. Usually this is done using coffer dams and caissons, which themselves may involve underwater work.