The membership of Allied Building Metal Industries Inc. were dismayed at the contents of your recent editorial "Making a City Safe for Cranes," in which you suggest that users should de-rate a crane's load chart so every lift in New York City defaults to a critical lift.Crawler cranes already have a standard 75% reduced chart; truck cranes are at 85%. A further reduction to 75% would limit the crawler capacity to 56%. There is already a built-in factor of safety in the manufacturer's approved charts. Cranes are typically load-tested to at least 130% of rated capacity. A further reduction to
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.