Surface and Underground Geodetic Control for Superconducting Super Collider

Abstract

Stringent accuracy specifications required that particular care be taken in the provision of geodetic control for the construction of the Superconducting Super Collider. The design and implementation of the surface geodetic control networks are described. The horizontal network was realized by Global Positioning System measurements, and the vertical network by means of precise geodetic leveling. The highly expansive soils in the project area required that the horizontal and vertical surface monuments be designed to be stable for the duration of the construction of the project. The methodology adopted for the densification of horizontal and vertical control from the surface networks to the shaft area, and an innovative technique used for the transfer of control into the underground facilities are described. The underground networks 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 underground monuments. Survey results for five tunnel half-sector breakthroughs are reported.