Key facts
11 km of underground line in a tunnel under Saltsjön Sea from Kungsträdgården to Nacka and Gullmarsplan. 7 new underground stations, up to 100 metres deep.
Construction method: drilling and blasting with rock treatment (pre-grouting) to reduce water flow into the tunnel.
Geology: predominantly healthy granite substrate (RCS > 100 MPa) Occasional glacial deposits