Análise comparativa das altitudes normais obtidas por nivelamento geométrico e posicionamento GNSS em um trecho de rodovia

Abstract

The use of methods related to the Global Navigation Satellite System (GNSS) has been gaining space in altitude applications, replacing the traditional methods of leveling. The use of the GNSS method provides geometric altitude that is different from those used in road works, but with later calculations it is possible to obtain altitudes related to a physical surface. The objective of the present work was to analyze the normal altitudes of the survey by the GNSS/leveling positioning method using as reference the altitudes obtained by geometric leveling. The methods were applied in a stretch of approximately 12 km from GO-020, with the implementation of safety points (PS) every 2 km. In the geometric leveling it was used Level Reference (RN) to support the surveys, while in the GNSS / Leveling positioning was used a station of the Brazilian Network of Continuous Monitoring (RBMC). When comparing normal altitudes, it was not possible to identify a pattern in the point-to-point discrepancy according to the baseline, verifying a maximum discrepancy of 0.1532 m. For the knowledge of the normal altitude of one or more points, the GNSS / Leveling positioning makes the procedure in the field more agile when compared to geometric leveling, however it requires a greater knowledge in the area of geodesy. Due to these factors, the performance of this research is of fundamental importance for applications in topography and geodesy, and may contribute to the knowledge of the reference surfaces. Due to the lack of regulations that regulate the altimetric survey carried out by GNSS positioning, it is not possible to determine the quality of the data resulting from this method, and it is still recommended today that for this type of survey use geometric leveling. In this research, the data from the GNSS / Leveling positioning were qualified according to the cartographic accuracy standard for digital cartographic products, being class A, with a 1: 1.000 scale.