Testing height accuracy of digital and optical levels
Ismat M. El Hassan
Levelling is a well known surveying operation through which elevations of points or the differences in elevations between points on the earth's surface are determined. It is an extremely vital operation for deriving necessary data for engineering and mapping projects. Instruments used in levelling operations have to give the standard accuracy required to execute the specified project. This paper reports about two height accuracy tests carried out on three differential levels: NA730-Leica optical automatic level, SDL30-Sokkia digital level and DNA03- Leica digital level. In the first test, a closed loop of 250m length was run from a starting point of given reduced level to five points and then back to the same starting point. The height closure errors for the three levels were: 5mm, 3mm and 2mm, respectively. In the second test, levelling was run for a longer loop of 450m length. Results of this test show that the three levels can give height misclosure errors of: 6mm, 4mm and 3mm, respectively. It is then conluded that the three levels can be used for engineering and surveying works that need third class accuracy. The DNA03 digital
Only personal, non-commercial use of this document is allowed.