Investigation of accuracy valley crossing leveling

In contemporary practices, point elevations or height differences can be determined using Geometric, Trigonometric, and GNSS leveling techniques. Different terrain conditions present various advantages and disadvantages of leveling techniques relative to each other. This thesis study focused on valley pass leveling, which is a specific application of geometric leveling technique. As it is known, the geometric leveling technique, particularly in wide-bedded valleys, is time-consuming, expensive, challenging, and susceptible to many modeling errors due to short observation lengths. Therefore, to minimize the disadvantages of geometric leveling in determining height differences in valley crossings, valley pass leveling equipment was developed by the Carl Zeiss Oberkochen company in 1960. This equipment consists of two Ni2 levels and a parallel glass and micrometer attached to the objectives of these levels, enabling the measurement of slope angles on lower and upper plates based on collimation values. In valley pass leveling, height differences are determined simultaneously and reciprocally using a special measurement model. In this study, measurements were taken in two selected application areas using valley traverse leveling, geometric leveling, eccentric trigonometric leveling, and GNSS leveling techniques, and the results obtained were compared. As a result, in application area-1, the height differences obtained using valley traverse leveling, geometric leveling, reciprocal simultaneous eccentric trigonometric leveling, and GNSS leveling techniques were determined as ΔHVG=0.04285m, ΔHGN=0.04535m, ΔHTN=0.04366m, and ΔHGNNS=0.04428m, respectively. Similarly, in application area-2, the height differences were determined as ΔHVG=0.23540m, ΔHGN=0.24193m, ΔHTN=0.24629m, and ΔHGNNS=0.24171m, respectively. Based on these data, it was concluded that the valley traverse leveling technique is particularly applicable under challenging terrain conditions such as valley crossings and water crossings.