ABSTRACT
The Stockholm metro Blue Line is being expanded southbound from the city center to Södermalm and Söderort as well as eastbound to Nacka. The entire railway line from the city to Nacka is developed underground and the tunneling works are conducted in densely populated areas with strict requirements to limit environmental impact. This paper presents some of the rock engineering challenges that were encountered during the excavation for the new stations in Sickla, Järla and Nacka. The excavation included passages underneath highway tunnels with low rock cover, a passage underneath a church and cemetery in Nacka as well as excavation of elevator and escalator shafts and jet grouting works. Excavation of the expansion to Nacka started with access tunnels for the new stations in Sickla, Järla and Nacka in 2020 and the planned construction period was set to 10 years. Operation of the Blue Line is expected to start in 2030. The geological conditions in the area vary between sections, from competent granites to fracture zones and graphite.
