Second Islisberg Tunnel Breaks ThroughA Herrenknecht tunnel boring machine (machine S-256) holed through on 12th July, 2006 the 4,645 m-long east tube of the Islisberg tunnel in Zurich, Switzerland. The 4,680 m-long west tube holed through on 21st April, 2005. After a very intensive but short reassembly phase, the 11.8 m-diameter TBM went back to work at the east tube on 7th July, 2005 (read E-News Weekly 30/2005). A lot of work remains to be done to complete the civil engineering works in December 2007. The cost of the tunnel amount to CHF562 million. Opening is programmed for end 2009 or early 2010. Each tube carries two lanes (7.75 m) and hard shoulders of 1 m at each side. They are lined with reinforced concrete segments (30 cm thick and 2 m long, 5+1 ring division) and an in-situ concrete inner shell with a PVC sealing membrane sandwiched in between. Cross passages (five for vehicles and 10 for pedestrians) built by drill and blast every 300 m between both tubes will provide evacuation in case of an incident. Every 150 m, SOS and hydrant recesses are installed. While tunnelling of the east tube was under way, work commenced in the western tube with the installation of the sealing membranes and the concreting of the inner shell (12.5 m formwork carriage, 125 m/week). Up to date, approx. 32,500 cubic metres of concrete has been poured for the inner shell, the false ceiling and the roadway. The ceiling is built with the aid of a crane-like device (formwork, reinforcement and self-consolidating concrete). The Islisberg tunnel is built by Marti Tunnelbau, Zueblin and Marti AG. Mucking-out was done using Marti Technik conveyor belts: one tunnel conveyor belt (5 km) and seven external conveyor sections (700 m), all of a capacity of 1,100 tonnes/hour. Other important equipment supplied by Marti Technik are formwork systems and a special concrete manipulator to produce the tunnel roof with self-compacting concrete. Visit www.martitechnik.ch The Islisberg tunnel is the gateway to central Switzerland. It links to Zurich's west ring road, which consists of the upper branches of a T-shaped infrastructure, with the Islisberg tunnel forming the leg of the T (see map). The west ring road consists of the 2 x 4,460 m Uetliberg tunnel, which also holed through recently on the A3 between west and south Zurich (click here), and the A4/A3 section from Urdorf to west Zurich (or Birmensdorf south bypass, 5.4 km) including the following tunnels: Honeret (2 x 450 m) on the Urdorf interchange, Ristet (448 m / 352 m) on the Uitikon entrance and exit ramps, Eggrain (443 m / 496 m), Hafnerberg (1,389 m / 1,347 m), Loffler (140 m) and Schauber (100 m), both on the Birmensdorf entrance and exit ramps, Aescher (2,176 m / 2,142 m), Eigi (2 x 125 m) and Ruteli (2 x 400 m). 79% (or 8.4 km) of its 10.6 kilometres will run in tunnels. The first section of the west ring road (2,930 m), between Urdorf and Birmensdorf, opened to traffic on 3rd July. This section includes the Eggrain and Hafnerberg tunnels. View pictures here. Visit www.islisbergtunnel.ch to view a video, www.arge-ibt.ch, www.westumfahrung.ch and www.zh.ch 30/06.