Determination of Orthometric Height for TBM in Hydrographic Surveys Work

Abstract

The temporary benchmark (TBM) is a reference value for each height. Observational data in the field always has differences and it is often with the measurement activities carried out. For example, the factor of measuring equipment, lack of skill in using measuring equipment and atmospheric effects that will cause differences to exist in the data. With the latest technology, level measurement using the Global Navigation Satellite System' (GNSS) can provide high accuracy and precision. There are several TBM points in the Lundu town that have not been adjusted for a long time and it is possible that these TBM have a different height than the actual height. In this study, two techniques were carried out, GNSS levelling using RTK technique and the levelling survey technique for the purpose of establishing TBM. The results of these two techniques will be studied and discussed. The comparison of height differences between the two techniques proves that GNSS levelling produces accurate and precise results.