Three dimensional displacement measurements (3D) are carried out within the Zone of influence in order to determine the movement on adjacent to the project structures and buildings. Reflectors are installed in tunnels, structures, etc. and the measurements are made with high precision total stations by the method of free station.
The reference network of the points, that is used for 3D measurements, consists of reference points with permanent labeling at the locations outside the zone of influence of the works or at locations remote to the excavation faces. The reference network will be checked at regular time intervals. All the measurements are corrected by the impact of the pressure and temperature diffractions. The precision of the measurements of total displacements is ± 2mm.