«Overhead line» corridor
This corridor offers operational advantages and comparatively low costs. The challenges are to minimise the impact on protected areas, to ensure that the overhead line, which runs across the valleys in places, is carefully integrated into the landscape, and to maintain a suitable distance to residential areas, villages and individual farms.
Cost: approximately CHF 60 – 80 million.
«Underground cable» corridor
This corridor variant offers the greatest possible protection of residential areas, landscapes and protected areas between Flumenthal and Therwil, with the exception of wooded areas, which it would be necessary to cut through. Compared to the other two options, an underground cable is more expensive. Further challenges are posed by the geological conditions, which make tunnel construction and the protection of groundwater more difficult, as well as placing increased demands on grid operations.
Cost: approximately CHF 230 – 290 million.
«Combination» corridor
This corridor largely corresponds to the overhead line corridor. As a result, it has comparable advantages and disadvantages. The five-kilometre-long cable route between Froloo in Therwil and Ettingen would provide relief for the residential areas of Therwil, Reinach and Ettingen, as well as the landscape conservation area to the east. However, it presents an additional challenge, because it would be necessary to provide as much protection as possible for the amphibian spawning area, which is of national importance.
Cost: approximately CHF 80 – 100 million.
Dismantling the old line
The project will reduce the impact on the residential areas between Flumenthal and Therwil. The plan is to install the new line as far away as possible from residential areas. In addition, the existing 145-kilovolt line, which runs partly through the middle of heavily populated areas, will be completely dismantled after the commissioning of the new 220-kilovolt line.