It’s been about 10 years since earthmoving contractors began playing around in earnest with three-dimensional grade controls guided by global-positioning systems, which can speed up estimating and shaping earthwork by 30% or more. A new book explains the ins and outs of how to set up a grade-control network on the jobsite. Researched, written and published by the staff of Memphis-based TrenchSafety and Supply Inc., the book explains how grade controls, such as lasers and GPS, can displace traditional staking costs on a large-scale contract, which can run up $100,000 or more in surveying fees. “You can also see significant
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.