A geodetic control survey consists of establishing the horizontal and/or vertical positions of points for the control of a project site. Terrasurv uses multi-constellation/multi-frequency GNSS receivers, high accuracy total stations, and geodetic leveling equipment to establish control networks. Terrasurv has calibrated invar leveling rods and has executed multiple second order leveling networks, several of which were submitted to the National Geodetic Survey for inclusion in the National Spatial Reference System (NSRS). See the Bluebook Services below for more information. All total stations used by Terrasurv are calibrated yearly on NGS Calibration Baselines (CBL).