Within the scope of this master thesis, the measurement principles of 3D-lasercanning and ultrasonic echo are used, to determine the thickness of various concrete elements for the purpose of comparison and assessment of their accuracy. For the determination of the thickness of the inner lining measurements are carried out in the rescue room of the lot KAT2 of the “Koralm” tunnel using a 3D-laser scanner and an ultrasonic flaw detector. In addition measurements on a tubing at the Chair of Subsurface Engineering cater for the evaluation of the accuracy of the ultrasonic echo principle. The evaluations of the laserscans are carried out with the manufacturer software of the company FARO Techn. INC. and those of the ultrasonic echo measurements using a MATLAB program provided by the company ACS Ltd which is the manufacturer of the ultrasonic flaw detector used. Within the scope of this thesis, this program is recoded to meet the purpose of determining and outputting the thickness measured. The results of the two measurement methods are merged using the software “AutoCAD”, which allows for displaying the 3D-laserscans and the points where the ultrasonic echo is applied in a single coordinate system. These final results are compared and verified.