SURFACE AND UNDERGROUND GEODETIC CONTROL FOR SUPERCONDUCTING SUPER COLLIDER

Stringent accuracy specifications required that particular care be tak en in the provision of geodetic control for the construction of the Su perconducting Super Collider. The design and implementation of the sur face geodetic control networks are described. The horizontal network w as realized by Global Positioning System measurements, and the vertica l network by means of precise geodetic leveling. The highly expansive soils in the project area required that the horizontal and vertical su rface monuments be designed to be stable for the duration of the const ruction of the project. The methodology adopted for the densification of horizontal and vertical control from the surface networks to the sh aft area, and an innovative technique used for the transfer of control into the underground facilities are described. The underground networ ks were designed so as to minimize the geometric weakness inherent in tunnel surveys. In the interests of economy, removable tunnel brackets were developed and used for the large number of horizontal undergroun d monuments. Survey results for five tunnel half-sector breakthroughs are reported.