RAPID TESTING: ANALYSIS OF GNSS RAPID STATIC OBSERVATIONS SUITABILITY FOR ENGINEERING SURVEYS IN URBAN ENVIRONMENTS IN THE TIME OF COVID-19

Abstract. This study aims to determine which rapid static observation durations would have acceptable accuracy for engineering surveys in urban environments (i.e. Metro Manila) in the time of COVID-19. Due to health concerns caused by the COVID-19 pandemic, Metro Manila has experienced various restrictions in mobility and time spent in public spaces in recent months. This has affected not only the lives and ways of work of the so-called front liners like nurses, doctors, and primary health care workers, but also the public at large which includes Land Surveyors. It is for this reason that this study was conducted, since a balance must be struck between the aim to get accurate engineering survey results and the health and safety of those who are conducting the measurements. Hence, the shortest possible time to conduct rapid static GNSS observation durations with acceptable results must be determined while ensuring that the conduct of the field survey would still be in compliance to the minimum health protocols (i.e. no mass gathering, maintenance of physical distancing, short time of interaction, etc.) set by the national government.

For this study, rapid static observations were made at varying time intervals (i.e. 2 minutes, 5 minutes, 10 minutes, 15 minutes, 30 minuntes, 1 hour, and 2 hours) at locations (i.e. open, with minimal obstructions, with significant obstructions) that would simulate archetypal situations when conducting engineering surveys in urban environments. Results were computed using fully constrained least square adjustment and results show that if all GNSS satellites are used in the computations, all time intervals would yield acceptable RMSE values, both for the horizontal (5 mm to 2 cm) and vertical (1 cm to 4 cm), for engineering surveys. However, if not all GNSS signals are available, it is best to use at least two GNSS satellite constellations (i.e. GPS-BeiDou, GPS-Glonass, Glonass-BeiDou) so that rapid static observations with acceptable accuracy can be made for as short as 5 minutes. For the “classical” accuracy standards, all rapid static observation durations yielded Order B relative precisions for the horizontal while most, except for the 30-minute duration, which yielded Third Order level results for the vertical.