A study on accuracy analysis of precision trigonometric levelling

Today geometric, trigonometric and GNSS levelling techniques are widely used in height determinations. The first method that comes to mind in both scientific studies and all kinds of engineering projects is the geometric levelling technique. Since the geometric levelling technique is affected by many model errors especially is rugged lands and its application is difficult and time taking, it has made up to date the re-research of trigonometric levelling techniques with the use of newly developed vertical angle and length observations in search of alternative methods. The aim is to investigate the accuracy of these trigonometric levelling techniques . For this purpose, the errors affecting the measurement model of trigonometric levelling techniques were first discussed and the theoretical accuracy expected from the trigonometric levelling techniques and the mean squared errors obtained as a result of the measurements made in the test area were compared. As a result unilateral and intermediate point trigonometric levelling techniques can be reached under ±5.00 mm accuracy. Beside reciprocal trigonometric levelling technique can be reached ±1.98 mm accuracy. As a result of these evaluaitons, it has been concluded that especially the reciprocal trigonometric levelling technique can be used in highways, railways , tunnels, etc. It can be said that using the trigonometric levelling technique instead of geometric levelling ın many infrastructure and base building projects will provide some advantages in terms of time and cost.