Photo by John Guzzon for ENR An operator moves a barrel through a slalom course during a competition this month in Las Vegas. Related Links: OSHA To Reopen Controversial Crane and Derrick Rules Viewpoint: OSHA Crane Rules Must Change Viewpoint: OSHA Crane Rules Have Merit Companies that test crane operators disagree with each other on the U.S. Occupational Safety & Health Administration's proposal to push back by three years mandatory certification for these workers. Public comments closed on March 12 for the proposed delay, which OSHA floated earlier in the year after industry groups had asked the safety agency to
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.