High-speed, high-resolution laser scanners that monitor the clearance envelope of railroad tracks have been available to European and Asian companies for some time. Now, a rail track scanner has been introduced to North America that is designed to capture track geometry and track envelope data in one pass, creating a 3D point cloud. The product claims 3mm accuracy. Photo : Courtesy Of Amberg Technologies Employed this GRP5000 to survey New York’s East Side Access, and No. 7 subway and was one of the first engineering firms to use it. “The amount of time required on the track is decreased,” says
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.