They are everywhere: on the streets, in the bushes, sometimes big and chunky, sometimes slim and wiry, sometimes a thick nail in the asphalt, even a massive stone or an iron pipe. Some still have their bright red color, but it disappears over time. And despite their presence they are somehow invisible boundary points. They indicate boundaries of parcels, ie by officially surveyed areas, are defined in their position and therefore visibly marked in the environment and anchored.
For Peter Rohde and his field team from the Survey Office of the circle Mettmann frontier points are however very well everywhere. Whether in Monheim, Langen field or elsewhere in the district: The surveyors are always on the spot, for example, if something new has been built or a parcel is to be divided. Then they measured the coordinates of the building or the new borders with measuring tape and ranging poles, a Global Navigation Satellite System, the matching stand, nicknamed the “spider”, and a total station – which is an instrument of angles and distances the coordinates of the desired can detect boundary points.
The team infected not only new limits on, it also summarizes existing and checks them. “The art is to adapt to the framework that already exists,” says Rohde. He holds on to scale drawn continuation plan the procedure when measuring fixed. In the County Road 18 in Mettmann Rohde has hit the concrete supports of a bridge over the Regiobahn on Landmarks of railway surveying 1921st At another point, the boundary points were even so old that he had to resort to Bürgermeistereikarte of 1831 in order to establish a reference to the historic border demarcation can. “Here was last surveyed nearly 200 years ago – so only ten years after Napoleon’s death,” says Rohde.
“The boundary points of time but have very different levels of accuracy.” While one can nowadays thanks to high-tech and satellite reception determine boundary points to two centimeter, 20 to 50 centimeters deviation were then common. And that was also at this point as follows: The original boundary line was not visible immediately and had to be reconstructed. Not so easy when the appropriate boundary points have accrued or now lie under the earth. “Here we rescued a walled drainage pipe under the embankment.
It was shown in the railroad surveying for structural reasons in the old survey plan with,” said Rohde. “We were able to make the line in the bushes locate and thereby establish the measurement line again. We have rediscovered some landmarks from 1921. We therefore had partly dug one meter deep.
” This lack of border points, the team then renewed in the old system and measured in modern and accurate coordinate system. “Sometimes we have to pick up the spade while checking and exposing older landmarks. This is a bit like a treasure hunt.” Some landmarks are through conversions deep underground, are weggepflügt or rinsed. This does not happen, new border points are underground secured with a bottle or ceramic cone.
The construction of a house, the division of the land or the purchase, sale and mortgage lending: There are many purposes that require the excerpts from the Real Estate Cadastre. Available these official statements are in Survey Office of the circle in Mettmann, but on the urban area also based in Langenfeld or Monheimer Bürgerbüro.