As California transportation officials vow to increase frequency of inspections on the troubled San Francisco-Oakland Bay Bridge, they had no firm estimate of when federal inspectors would okay its reopening to traffic. For the second time in two months, crews have worked non-stop to install an emergency eyebar repair on the critical crossing, which usually carries 280,000 daily vehicles. The original fix made over Labor Day weekend consisted of a steel saddle brace wrapping around a broken beam of the steel truss. That brace snapped during the windy Oct. 27 evening commute, dropping a 5,000-lb crossbeam and steel connectors into
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.