In the course of the numerous grid expansion projects in Germany, a large number of obstacles such as existing infrastructure, rivers or protected areas have to be passed under when laying underground cables. The SuedLink extra-high voltage direct current line transports electricity generated from wind power from northern Germany to the industrial centers in southern Germany. HDD rigs have drilled the boreholes for laying cable protection pipes, which SuedLink will use to cross under the river Tauber, a federal highway and other transport infrastructure. 

In Germany alone, the grid expansion projects, of which SuedLink is the largest, involve around 4,500 so-called crossings. Crossings are the most challenging sections of underground high-voltage cable routes. Trenchless technologies are essential to cross geographic obstacles such as rivers, swamps and wetlands, to protect nature reserves and recreational areas, groundwater zones, the landscape and valuable agricultural land, and to pass under transportation infrastructure, supply and disposal lines and buildings.

The crossing under the Tauber, the B 290 federal highway, a long-distance cycle path and a local recreation area was carried out from both ends of the drive. The so-called “intersection” method, in which both machines meet in the middle of the drilling section, was carried out by an electric HDD rig HK300TE with a pulling force of 300 tons and a diesel-powered rig HK150C. The special features of the project included the length of the boreholes of 854 meters and a considerable difference in height. Due to the geology, steel pipes with a diameter of 323.9 mm were laid, into which the PE cable protection pipes were pulled.