A funding delay, a cableway collapse and a death: Construction of the Hoover Dam Bypass is a challenge-filled saga that rivals the building of the historic dam itself. But the light at the end of the canyon is beckoning. North America’s longest single-arch concrete crossing, at 1,960 ft, now soars 88 ft over the Colorado River and is scheduled to open to traffic in November 2010. It will carry vehicles 1,500 ft downstream from Hoover Dam, spanning the Black Canyon at the borders of Nevada and Arizona and answering a need that dates back to the 1960s. Slide Show Photo:
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.