The scheduled August 6 breakthrough of the Laerdal Tunnel (T&T International, June ’99, p9), claimed to be the longest road tunnel in the world, has been delayed because of a tunnel collapse at the face. There were no injuries and the breakthrough date is now expected to be the end of September.

The 18m long, up to 10m deep collapse occurred in mid-June, before the start of the July holidays. It was on the south-north drive from the Aurland side, 11km from the start and 1km below surface, as a crew from the Norwegian Public Roads Administration was carrying out rockbolting activities. Due to adverse rock conditions there are high stresses, which have necessitiated the application of heavy support with rockbolts and fibre reinforced shotcrete.

Approximately 1200m3 of collapsed material filled the excavated area, which has now been cleared, filled with concrete and re-excavated. The distance left to breakthrough is 110m.

Excavation is now proceeding slowly at one round per day, 3-4m per round.