Photo: Controled Demolition Inc. Before Photo: Controled Demolition Inc. After With cracks as sharp as the frozen Arctic air, a 1,375-ft-tall steel communications tower in Port Clarence, Alaska, was demolished on April 28, the first step in the decommissioning of the U.S. Coast Guard’s network of LORAN radio navigation facilities. The 400-ton, 45-segment triangular tower is the tallest structure to be felled by explosives, says Controlled Demolition Inc., Phoenix, Md., which performed the operation as a subcontractor to Jacobs Field Services North America. The remote installation, located 75 miles north of Nome, was one of 24 land-based LORAN stations in
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.