Open print view

Back to Homepage


Switzerland is moving

Coordinates are essential to define the location of a point. Because of Switzerland constantly moving, coordinates lose their accuracy over the years. swisstopo checks the changes every six years and thereby ensures that Swiss coordinates remain reliable. This enables, among other things, construction and maintenance of large infrastructure projects, such as the tracks for high-speed trains.

18.07.2022 | DKW

GNSS measurement, setting up the instruments


Gliding smoothly over the tracks at speeds up to 200km/h – in Switzerland, travelling by train is part of everyday life for many people. When it comes to the construction of railway lines, especially for high-speed trains, the national survey plays a vital role with its up-to-date data. Rails have to be laid precisely according to plan and as evenly as possible. They cover long distances with gradients and curves, running over bridges and through tunnels. 

Every millimetre counts

Gotthard south portal – accurate coordinates are essential for large-scale infrastructure projects

To ensure that the rails are still where they ought to be after several kilometres of distance, it is necessary to have position data in millimetre accuracy. Referenced to the geodetic network and embedded in the national coordinate system, it is possible to determine exactly where to place the rails. Based on known geodetic points, Switzerland's national, automatic Global Navigation Satellite System (GNSS) network known as AGNES, which is operated by Swisstopo, allows the determination of the millimetre exact coordinate of any given point in the country.  

Coordinates must remain stable

Checking the geodetic point on Mount Menzberg in Canton Lucerne

The earth's surface is constantly moving. This also applies to Switzerland, located almost entirely on the Eurasian tectonic plate. The plate drifts towards northeast at a rate of about 2.5 cm per year. However, this shift is not critical for surveying as the Swiss reference system is tied to the Eurasian plate. Within Switzerland, however, there are additional local shifts of 1 to 2 mm per year. Hence, the experts at swisstopo re-survey our country every six years.

All 220 geodetic points are checked to ensure the continuous accuracy of the coordinates. Thereby shifts in the terrain are detected early enough and incorporated into the model in good time. For long-time and large-scale construction sites such as railway lines, tunnels or bridges, the exact position information is indispensable. The same applies to the official cadastral survey which documents, amongst other things property boundaries. The data must remain tenacious for a long time so that even decades later it is still clear where one plot ends and the next begins.

What if...?

Suppose these control-measurements were not conducted. Geodetic points might have shifted unnoticed, for example due to being located on a slope that became unstable. Also a construction site or inclement weather might alter a point.

For the cited construction or multi-year renovation of infrastructure projects, such as the aforementioned railway line, this could have a major impact on costs and safety. If users could no longer depend on the reliability of the Swiss terrestrial reference frame, a separate coordinate system would have to be created for each project, involving a lot of time and work. Problems would occur more frequently because coordinates measured at different times would no longer match.

The current measurement campaign of swisstopo involves updating data on the location of all 220 geodetic points, thereby ensuring the accuracy and dependability of the coordinates for Switzerland. Current and new projects will be able to access up-to-date data for the coming years. Through that the collected data also contributes to your next railway journey.

How are coordinates determined?

The reference system forms the theoretical basis for determining coordinates. The Zimmerwald geostation establishes the link between the national reference frame and the International Terrestrial Reference Frame.

The reference frame then links the abstract coordinate system to the real world. With the help of the automatic GNSS network and the 220 geodetic points [Link: Geodetic points (admin.ch)] distributed throughout the country, Switzerland's terrain is surveyed and integrated into the reference system. Finally, the surface of the spherical earth is mapped onto a map projection. This completes the coordinate system. 


Back to Homepage

Federal Office of Topography swisstopo Seftigenstrasse 264
P.O. Box
3084 Wabern
Tel.
+41 58 469 01 11

E-mail


Relevant authority

Communication and Web
E-mail

Federal Office of Topography swisstopo

Seftigenstrasse 264
P.O. Box
3084 Wabern

Show map