Underground Power Lines

Expansion and Reconstruction of Transmission Systems

The energy system transformation requires the construction of efficient power lines in North-South direction to distribute electricity, generated by wind turbines, throughout the entire German territory. Due to this distribution of energy a further adaption of connection lines is necessary. Regardless of this large transformation grids and hubs have also to be levelled.

Thereby, the underground construction with extensive civil and structural engineering activities becomes more important. With regard to this sector STREICHER looks back on longterm experience and carries out conventional laying methods (open and trenchless) as well as design and routing activities.

Scope of Services

  • Execution of power lines of different voltage levels by means of modern laying techniques (e.g. HDD)
  • Border detection and routing
  • Assembly and connection techniques
  • Different measuring and inspection systems
  • Digital calibration and documentation


Development of a Trench Sledge for Underground Installation of Cables and Cable Conduits

On behalf of 50Hertz Transmission GmbH STREICHER has developed a prototype of a trench sledge for cable routing. Background of this project is to improve the current installation process for cables and cable conduits as part of the high voltage direct current network expansion in Germany with regard to efficiency and laying precision.
The trench sledge has a length of approx. 22 m and a weight of 18.5 t. A first test was very successful. Within one step two PE cabel conduits (da 280 mm), two earthing ropes and two empty conduits for fibre-optic cables (da 50 mm) were laid precisely. In the course of the cable installation embedment material (material mix of fine gravel, sand, silt and clay) was filled into the trench and mechanically compressed in two stages by using the sledge. During the test a 50 t excavator pulled the trench sledge. This excavator also guaranteed the energy supply of the compactors of the trench sledge.