Contract for 83m2 x 8.6 km two-lane second tube awarded to jv of Ostu Stettin and Hinteregger. Geology comprises limestone, dolomite and shale. Contract commenced July, 1999 on four-year schedule. August 1999.
Contracting joint venture Ostu-Stettin/Hinteregger reports completion of 60 % of the raw tunnelling on the 9.9 km-long x 90 sq m west tube of Plabutsch road tunnel. The north face has advanced 2.8 km and the south face 2.2 km, using two Atlas Copco L3C drillrigs equipped with automatic boom control. The central section of tunnel with fan chambers and ventilation shafts was constructed along with the east tube 18 years ago. Top heading excavations are supported by 4 m-long Super Swellex bolts immediately after blasting, using the drillrig onboard pumps. North end geology was dolomite for the first 600 m, followed by a section of squeezing schist. The latter required face bolting using 3 m-long threaded Ibo Anker self-drilling extension rockbolts to produce 3 x 15 m strings which were grouted into place, and lattice girder support with shotcrete applied by Aliva twin-boom, crawler-mounted jumbo. Visit www.oestu-stettin.at and www.atlascopco.com November 2000.