Sequential excavation of top heading, bench and invert due to commence by OHL/Semaica on 2 x 140 sq m three-lane tunnels using ITC-Schaeff excavators from four portals. Tubes are 805 m-long and 1.33 km-long of which 264 m and 585 m respectively are natural tunnel and the remainder cut-and-cover. Friable, weathered rock will be arched, bolted and shotcreted. 12 m umbrella drilling may be required in sections, and 80 cm-thick reinforced, waterproofed in-situ concrete lining will be installed throughout. Contract value $60 million for completion September, 2002. Visit www.schaeff.com December 2000.
