Abstract
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.
Highlights
The COVID-19 pandemic has caused numerous disruptions in the way people do things, especially in the conduct of their work
COVID-19 induced restrictions, like minimum physical distancing and travel curfews, have introduced additional burdens to Land Surveyors in doing Global Navigation Satellite Systems (GNSS) observations in urban environments, where there are already a lot of possible sources of errors like multi-path sources and signal disruptions especially when observations are made in urban canyons, narrow pathways, and densely populated areas
It can be said that computed root mean square error (RMSE) based from field observations generally conform to the RMSE declared by manufacturers of their GNSS instruments especially for observations that are at least 5 minutes long when using (1) all GNSS signals, (2) those using GPS-only and BeiDou-only signals and (3) observations using at least two satellite signals in combination
Summary
The COVID-19 pandemic has caused numerous disruptions in the way people do things (i.e. the “new normal”), especially in the conduct of their work (i.e. shift from face-to-face interactions to work-from-home arrangements and/or skeleton workforce, etc.). COVID-19 induced restrictions, like minimum physical distancing and travel curfews, have introduced additional burdens to Land Surveyors in doing GNSS observations in urban environments, where there are already a lot of possible sources of errors like multi-path sources and signal disruptions especially when observations are made in urban canyons, narrow pathways, and densely populated areas. It is recognized that a balance must be struct between accuracy and precision of Geodetic observations vis-a-vis health and safety of the field personnel doing the observations. It is for this reason that this academic study on rapid static GNSS observations was initiated
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