By April 2009 the tunnel excavation was 85% complete.
A tunnel excavation has revealed a rock so dense that it cannot be penetrated by even the strongest drill.
His body of research includes finding hundreds of previously unseen panoramas, mass graves of soldiers and tunnel excavations.
The unique double-deck, three lanes per direction design comprises a large, single tunnel excavation.
The plans include two tunnel excavations with a diameter of 2.40 m using compressed air and a cover plate.
The disposal of up to 250,000 cubic metres of spoil from the tunnel excavation is also considered problematic.
This was no doubt caused by the tunnel excavation under the outer edge of the volcano.
The full tunnel excavation was completed in April 1833.
Unexpected geological conditions at the dam site led to landslides and slower tunnel excavation.
Construction commenced in September 1980, with tunnel excavation commencing in January 1981.