German prosecutor officials are investigating possible criminal falsification of construction survey data on Cologne’s roughly $550 million North-South urban rail project, scene of a building collapse last March. In parallel, diaphragm walls being used in construction of one the line’s underground stations have been found to be about 80% short of specified dowel bars. These, as yet unconnected, findings recently emerged from investigations into the March 3, 2009 collapse of the city’s historical archive building. The building was undermined when a section of railroad tunnel under construction in nearby Waidmarkt collapsed. No official cause for the tunnel failure has yet
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.