The Washington State Dept. of Transportation describes the highway off-ramp improperly built on a new interchange in east Tacoma as “unfortunate and embarrassing.” It’s also expensive. A change order for nearly $900,000 —out of the project’s contingency fund at the cost of WSDOT—was worked out with project contractor Guy F. Atkinson Construction. The Broomfield, Colo.-based contractor already has started removing retaining-wall panels to flatten the ramp, which was mistakenly built at the wrong grade. Photo: WSDOT Demolition begins for the fix to a wrongly placed Tacoma, Wash., interchange ramp. The eastbound ramp of the $119.9-million Nalley Valley interchange—at which Interstate
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.