A brief history of the geodetic survey of Canada

Nagy, D. (2011) A brief history of the geodetic survey of Canada. Acta Geodaetica et Geophysica Hungarica, 46 (4). pp. 471-480. ISSN 1217-8977

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Abstract

This is a brief history of how a small group of people carried out its mandate to survey and map Canada in spite of the hostile environment — the second largest country in the world — in a 100 years.The levelling started from Halifax and by 1916 it reached Vancouver completing the coast-to-coast connection, encompassing about 22 000 km distance of which 94% was done on the railway tracks. The adjustment was carried out in 9 steps, it included the tide gauges in both the east and west coast, and was completed in 1928. The final adjustment used about 37 000 km length, from which 30 000 was measured by the GS. The first order re-levelling started after the Second World War and was carried out on the Trans-Canada highway. By 1994 Canada was covered by a levelling network of about 109 747 km. After this date there was no more conventional levelling.The triangulation used cross-braced quadrilaterals, based on the method used in the USA. In 1961 the GS started to use the conventional methods of chains of triangles. The measurements covered mostly the very southern part of Canada. The mapping of middle and northern part of the country had to await until the electronic era, which was practically made for Canada.The lower order accuracy was provided by Shoran, using about the average of 400 km line length for triangulation. Between 1947 and 1957 this method provided 501 measured triangle sides of about 200 000 km in total length and provided 119 base-point covering about 65% of Canada.The other method, the Aerodist — the Tellurometer version of Shoran — provided second order accuracy. The triangulation, using cross-braced quadrilaterals, with 100 km sides gave 219 points and covered about 25% of the land area of Canada. The measurements were done between 1965 and 1973.Recent measurements make use of GPS for geodetic position determination. A 10 year program started in 1987. In 1992 the GSD defined an official geoid to be used in connection with all satellite work.

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