The Anneberg-Skanstull tunnel is a new high voltage cable tunnel currently constructed in the rock below the Swedish capital of Stockholm. The purpose of the cable tunnel is to ensure a balanced and reliable Swedish electrical power system by its owner Svenska kraftnät, an authority responsible for the Swedish National Grid. The tunnel for a new 400 kV cable connection is one of many ongoing projects in the Stockholm region to strengthen the national grid and to increase the capacity to meet the growing need for electricity. The tunnel will be 13.4 km long, with a diameter of 5 meters and connected between two substations, Anneberg in the north and Skanstull in the south. The tunnel depth varies between 50 and 100 meters. The tunnel has two passages below sea level, Stocksundet and Strömmen, a bay of the Baltic Sea. There will also be six vertical ventilation shafts along the tunnel, 40 to 100 meters deep. The tunnel is mainly excavated using a TBM, except part of the passage at Strömmen, planned as a conventional drill and blast tunnel. The TBM is an open gripper manufactured for the execution of pre-excavation grouting works, which means it carries equipment for the drilling of grout holes, water pressure testing and pre-excavation grouting. The grouting works is carried out as either selective or systematic pre-excavation grouting by means of rock fracture grouting with cementitious grouts. Curtain grouting is used for the vertical ventilation shafts.