In 2009, at the Gdansk University of Technology and Polish Naval Academy there has been carried out, for the first time, continuous satellite surveying of railway track by the use of the relative phase method based on the Polish Active Geodetic Network ASG-EUPOS and RTK (GPRS) real time service - NAVGEO. The analysis indicated strong connection between location of GNSS receiver and accuracy of position determination, the horizon obstruction deteriorated accuracy and impacts terrain obstructions, the precise GPS planning process on the position solution. It can be stated that implemented measuring technique opens a whole new perspective on applied research. As proved, it enables very precise determination of basic data definition for railway line modernization design. On-going research works focuses on the GNSS multi-receivers platform evaluation for projecting and stocktaking.
Analyses also focused on the values of deviations of transverse position XTE (Cross Track Error). In order to eliminate the influence of random measurement errors and to obtain the coordinates representing the actual shape of the track, the XTE variable was performed by different statistical and regression methods (least square method - LSM, weighted least squares - WLS, Linear Chebyshev low-pass filtering and fast Fourier transform). The paper presents the result of trial analyses realized on the newly constructed (rectilinear) and old-used up railway lines. The authors were searching the methods for filtering random measurement GNSS errors different from instantaneous shape deformations of the straight rail track.