Preliminary determination of spatial geodetic monitoring accuracy for free station method

In this paper, one of the modern spatial geodetic monitoring method was described: a free station method. This method is effectively used during monitoring of displacements for buildings and constructions under dynamic load. Theoretical prove for rigorous preliminary computing of displacements determination accuracy using free station method was done. The analysis of errors, which influence on the accuracy of spatial monitoring, was presented. It was found out that errors of initial survey network, errors of free station coordinates and errors of spatial monitoring targets coordinates were influencing on the accuracy of measured displacements using the free station method. Using the covariance transformation rules, rigorous formulas for preliminary calculation of displacement determination accuracy were obtained. Experimental calculations were carried out using these rigorous formulas, deploying practical results of spatial geodetic monitoring of transport structure situated in the zone of metro line underground construction. Executed calculations proved that chosen method of spatial deformation monitoring and equipment accuracy conformed the design requirements.