Construction safety, including safety of crane operations, is a priority for David Michaels, the chief of the federal Occupational Safety and Health Administration. Michaels, who became assistant secretary of labor for occupational safety and health last December, signed a voluntary agreement on May 17 with the National Center for Construction Education and Research, for crane-operator certification--the fourth such program to receive formal OSHA recognition since 1999. Before moving to the top OSHA post, Michaels was professor of environmental and occupational health at George Washington University�s School of Public Health and Health Services. Earlier, he was the Dept. of Energy's assistant
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.