Establishing Vertical Control on the Hoover Dam Bypass-Colorado River Bridge

摘要

The use of reciprocal trigonometric leveling with reciprocal zenith angles for vertical control will meet the 0.005-ft vertical tolerance specification for arch construction layout. rnThe science and processes of surveying take on many faces and have numerous assumptions tied to them. Many people see surveying" as an exact science with definite results and absolute answers. Whether the solution to be obtained is the resolution of a boundary, the proper geodetic application of a large-scale project coordinate system, or construction staking within a local project site, there will invariably be both systematic and random errors. It is the surveyor's job to be aware of all potential sources of measurement error. In deciding which survey methods are appropriate, one must consider factors such as the sources of error propagation inherent with each method, the economics of each method, the type of measurement required, and other related factors.