The Tief4 consortium, commissioned by Amprion, carried out early onshore works for BorWin4 (and DolWin4) by constructing a cable protection pipe system into which the HVDC power cables would later be pulled. The works included pre-welding pipe strings and installing them using both closed construction methods (primarily horizontal directional drilling) and open-trench construction along the onshore route towards the converter station area in Lingen.