History of precise levelling in Canada and the North American vertical datum readjustment

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1986
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Abstract
In 1977, the Canadian Geodetic Survey in cooperation with the United States National Geodetic Survey started on the readjustment of North American geodeticvertica networks on a redefined datum. This project has been assigned the title of 1988 North American Vertical Datum (NAVD88). This colossal task requires studies of (NAVD88) technical problems associated with the type and the amount of data involved. It also requires the automation of the levelling data. This thesis is in two parts. The first part is a synthesis of the precise levelling work in Canada since its beginning, in 1883, until today. Precise levelling was started in 1883 by the Department of Public Works (1883-1930), followed by the Geodetic Survey in (1906-present) and then by Topographical Survey in (1912-1925). The second part deals with the errors associated with the levelling work. It describes the errors and their effect on the levelling data. Numerical tests show that the precision of levelling, for first order in southern Canada, has improved from a standard deviation of the mean of 1.36 mm to 0.63 mm/km and the percentage of relevels has been reduced from 17. 4 to 5. 3 in recent years. But there are still the systematic errors which required further investigations. The author believes that such basic information will help to improve the quality of the NAVD88 adjustment. It is hoped that the recommendations will be the springboard to fruitful research related to this project. This information should also be a great asset in the automation of the levelling data especially with regard to the type of data to be automated and analyzed.
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Bibliography: p. 194-203.
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Citation
Gareau, R. M. (1986). History of precise levelling in Canada and the North American vertical datum readjustment (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/13809
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