Swiss coordinate system

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The Swiss coordinate system (or Swiss grid) is a geographic coordinate system used in Switzerland for maps and surveying by the Swiss Federal Office of Topography (Swisstopo).

The map projection used is Oblique Mercator on an 1841 Bessel ellipsoid.

The geodetic datum CH1903 uses as fundamental point the old observatory of Berne ( 46°57′08.66″N, 7°26′22.50″E), the current location of the Institut für exakte Wissenschaften of the University of Berne. In order to avoid errors during coordinate transmissions, the coordinates of this point are 600'000 m E / 200'000 m N. The 0 / 0 coordinate is located near Bordeaux, France. This definition invokes the following effects:

All coordinates are always positive, since Switzerland is located in the 1st quadrant of the coordinate system.
Furthermore, the whole area of Switzerland is located below the y=x line of the coordinate system. Thus, all E-coordinates are always bigger than N-coordinates.
Finally, as the entire area of Switzerland is located between 100 and 999 km east (respectively north) of the 0 / 0 reference point, all coordinates have three digits (using kilometers) or six digits (using meters).

Devised for the national land survey of 1995 (LV 95 for Landesvermessung 1995), the CH1903+ datum is based on WGS84. The coordinates of its new reference point, the Zimmerwald observatory, should maintain the CH1903 coordinates as far as possible. The easting and northing is increased by 2 mio/1 mio.