Control surveys for British Columbia terrain resource information management program

Control surveys in support of British Columbia´s terrain resource information management (TRIM) program have been carried out. In 1986, 138 stations were surveyed over a 42-day period using Trimble 4000SX GPS (Global Positioning System) receivers. In 1987, 260 stations were surveyed within a 53-day period and during the 1988 field season the plan was to survey 149 stations within a 68-day period. The field and office techniques and their evolution are reviewed and the problems encountered during each of the three years and their solutions are discussed. It is concluded that, while there have been problems, the GPS systems have proved themselves to be dependable and have produced accurate results for a large number of stations during limited field seasons