Officials say the catastrophic 2007 collapse of the Interstate 35W bridge in Minnesota that killed 13 people revealed shortcomings in visual bridge-inspection techniques, particularly of gusset plates and other components. Mark Bagnard, lead investigator for the National Transportation Safety Board, told attendees at the annual International Bridge Conference, held this year in Pittsburgh on June 14-17, that the state’s load ratings of bridges were inadequately measured and did not include gusset plates. As far back as 2003, photos showed the gusset plates were bowed. “Despite the photos, this bowing was not reported in either of two inspections.…One inspector actually saw
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.