Optic fibre cables can be installed directly into the ground but usually they are placed in protective tubes called subduct pipes. The filling of pipes with sub-pipes permits a high capacity of fibre optic cables. Special guiding ribs in the inner wall of the HDPE pipes reduce friction and make it possible to blow in several hundreds of meters of subduct. High-density polyethylene (HDPE) pipes offer much more protection against breakage or damage than buried cables. The potential damage caused by improper excavation, road or weather conditions is strongly reduced. Replacing cables or adding new or additional cables can be done easier, faster and more efficiently when they're placed in protective tubing.