For the second time in four months a 240-ton leaf of a main Ohio River miter-gate lock has failed, severely restricting shipping and signaling, once again, that it can be perilous to depend on aging infrastructure. Photo: USACE Photo: USACE Snapped Miter anchor arm may have fallen to fatigue. X-rays of the other arms at the lock show no cracks. On Jan. 27, as the main-chamber, downstream gate of the Greenup Lock and Dam, near Greenup, Ky., neared closure, operators heard a pop and the landside leaf canted over, but it did not fall. Mike Keathley, the U.S. Army Corps
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.