With the fourth and last 10,000-tonne concrete element sunk, the U.K.’s new, 1.5-km-long River Tyne Tunnel crossed a major milestone late last month, but a missed dredging window, imposed to protect salmon migration, will cost a delay of two months. Photo: New Tyne Tunnel. Four sunken tube elements were built in dry dock by the contractor. Photo: New Tyne Tunnel. All four sunken tube segments have been floated into place on the Tyne River. Related Links: Tyne Tunnel Sunk Work now focuses on the final connections between the four 400-m-long concrete elements of the sunken tube tunnel (STT) near Newcastle.
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.