Geodetic Reference Systems in GPS Environment

The respective roles of government and the private sector in geodetic surveying are relative and whatever they are now, they are about to change. To a major degree existing roles have been established by: (1) National interest and need; (2) economics; and (3) technology. The latter two are intertwined. The extent of the existing National Geodetic Reference System (NGRS), for example, was based partly on the need to provide sufficient density to permit local surveys (private or government) access to the datum within certain economic bounds. These economic bounds are driven, almost exclusively, by the methodologies used. GPS has the potential for changing these economic boundaries and, therefore, revising the nature of geodetic reference systems. A backbone national reference system at 500 km spacing with secondary stations spaced between 50 km and 200 km should suffice in a full GPS environment.