Longest Tunnel Breaks Through on Sweden's Bothnia LineThe 5.6 km Namntall tunnel, one of 16 such constructions on the Bothnia line and Sweden's longest railway tunnel, broke through on 30th October, 2006. A rescue tunnel every 500 metres connects the main tunnel with the service tunnel, of the same length, that runs parallel to it. In all, the Namntall tunnel system is 13 km long.The tunnel forms part of contract E3541, awarded to Skanska, which also includes the 5.2 km Björneböle tunnel, 32 kilometres of railway embankment and 14 bridges. Valued at around SEK1.3 billion, this is the single largest contract. Work is continuous, twenty-four hours a day, seven days a week. In total, around 300 people are employed on the contract, approximately 120 of these on the Namntall tunnel. Work started in March 2004 and uses the conventional drill-and-blast method, with three Atlas Copco Rocket Boomer 353 drill rigs and three Rocket Boomer XL3C drill rigs. Each round of charges takes the crews 5.5 metres forwards. The Namntall tunnel required the use of 55,000 bolts, 1,500 tonnes of cement injection and 25,000 cubic metres of shotcrete. It is estimated that all major work on the tunnel will be completed in summer 2007. Visit www.atlascopco.com The Bothnia line's 39 km of tunnels includes 16 rail tunnels totalling 24.4 km in length. Service tunnels account for the remaining 14.6 km. Four of the service tunnels are built parallel to the larger rail tunnels - Askott (3.3 km), Namntall (5.6 km), Björnböle (5.2 km) and Varvsberg (2 km). The service tunnels for Askott and Varvsberg are 2.3 and 1.1 km long, respectively. The total volume of the rock tunnels is around 2.2 million cubic metres.The tunnels have been excavated through Scandinavian gneiss and granite formations and meta-greywacke. The rock is generally of good quality with typical Q-values of between 1 and 100. Grouted in rock bolts and fibre-reinforced shotcrete are being employed as the standard forms of rock reinforcement. Continuous pre-injection is being used in the construction of all tunnels.The Bothnia line is a 190 km single-track, high speed rail link running from Kramfors in the south to Umea in the north, is one of Scandinavia's largest railway projects. Botniabanan AB is in charge of designing and building the line. The entire Bothnia line project is split into 130 contracts. Work started in August 1999 and is scheduled for completion in 2008. The total estimated cost is SEK15 billion. Visit www.botniabanan.seThe project's goal is the improvement of communications and freight transport in the north of Scandinavia. The present main railway, which runs inland and was built early in the 20th century, is nearing its full capacity. A fully developed Bothnia line will vastly improve passenger and goods transport to and from northern Scandinavia. Click here and se/16. 51-52/06.