Photo: APimages/AN Heisenfelt The fabric roof of the Metrodome Stadium in Minneapolis collapsed on Dec. 12 under the weight of 17 or more inches of wet snow. Steve Maki, the stadium’s director of facilities and engineering, said a seven-person snow-removal crew retreated from the roof when winds gusting to 40 mph made working unsafe. Maki says that, early Sunday morning, one fabric roof panel gave way because of the snow load, which overstressed two more panels that also then failed. The roof was fabricated and installed by Birdair Inc., Amherst, N.Y., in 1981. Maki says three samples of roof fabric
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.