Twice a month, Elmar Brockmann spends a night on top of the Längenberg, a hill to the south of Bern. He is supervisor of the Zimmerwald geostation, which swisstopo operates together with the Astronomical Institute of the University of Bern. “Zimmerwald is the location of the base station and the most important reference point for the Swiss national survey,” explains Elmar Brockmann. The astronomy specialist and surveying engineer joined swisstopo in 1999 and has largely influenced the development of the new national survey (LV95), which forms the basis for the production of the sets of national maps and serves as the basic infrastructure for the survey. With this system it is possible to position locations with millimetre precision. 

Everything takes place automatically

Most of the time, Elmar Brockmann does not work overnight – he mainly operates from his office at swisstopo’s headquarters in Wabern, just outside Bern. “My task is to supervise the network of coordinate references,” he says. This description makes his job sound fairly straightforward, but in reality it is highly complex: throughout Switzerland there are measuring stations in 30 or so locations, and each station is equipped with state-of-the-art technology.

The Zimmerwald geostation is equipped with a laser that is pointed at a satellite through a telescope. The laser beam ensures that the distance between the telescope and the satellite is measured precisely. The other stations are equipped with devices that permanently receive data from navigation satellites. The results are forwarded at one-second intervals to swisstopo’s computer centre. “This all takes place automatically,” explains Elmar Brockmann. If an error message is received from one of the stations, for example because the antenna has become soiled, the system detects this and triggers an alarm.

Planning measurement campaigns

The network of coordinate references also includes around 200 fixed terrain points which have to be re-measured every six years by swisstopo personnel within the scope of a measurement campaign. The next campaign will be implemented this year between May and September. At each point, devices are carefully installed that record data over a period of 48 hours. “The position of the measurement must be accurate to within a millimetre in order to correctly determine the point,” explains Elmar Brockmann. The data are then evaluated and new coordinates are calculated. 

Globally networked

Elmar Brockmann’s duties extend well beyond Switzerland’s borders, however: the Swiss network is connected to a European and global reference frame. “International cooperation plays a significant role in the coordination of global surveying,” he points out. Each country has to contribute. He therefore maintains close contacts with fellow scientists abroad and regularly attends international congresses. At the international level too, it is important to move as a team in a common direction, he adds.

Alps are shifting

Elmar Brockmann is currently confronting a geological phenomenon: “Measurements carried out in the past two decades clearly show that the Alps are shifting by a few millimetres each year.” And even greater movements have been detected in other regions of the world, for example in Italy, Greece and Turkey. In view of this, Elmar Brockmann has established a European workgroup in order to secure the exchange of data and find solutions for future measurements. The existing coordinates system is static and will need to be supplemented in the long term so that the different shifts in the various regions of the country can be taken into account.