Breakthrough was achieved on t6 July for the 1100m Kalldal Tunnel, the first excavated on the Botnia Rail Line in Sweden. The $930m Botnia Rail Line, located in the north of Sweden, will be 190 km long and includes 30 km of tunnel. The line is planned to be operational at the beginning of 2006.

‘The breakthrough on the Kalldal tunnel took place on schedule and finishing work will now be carried out before the project is handed over in May 2001" said Kari Korhonen, project manager for contractor Lemminkainen Construction.

Finishing work will involve sealing cracks with micro cement, reinforcing the walls with rock bolts and shotcreting walls and roof. Electrics will installed, handrails fitted and the railroad surface prepared ready for the rails. The $7M finishing also includes 1km of terracing work involving ground reinforcement with piles and vertical drainage, plus two bridges.

The tunnel was excavated from one direction using a fully automatic Tamrock Titan Data three-boom rig to drill through rock consisting of dolerite, granite and gneiss, and advancing 5m at a time. Once the rig was set up in an east-west direction with the aid of a laser, the drilling was done automatically. After drilling the holes were charged with a combination of Dynamex and Anfo explosives.

Scaling, the spraying of water to lay the dust plus the loading of the excavated rock onto dumpers was all done with the aid of a Brøyt 43 T ED excavator that can handle 600t of rock an hour. It was powered electrically, improving the working environment in comparison with diesel, which it can also use.

"On previous contracts we needed two machines and a tunneller to spray water manually, but on this contract the Brøyt has coped with it all" points out Hans Frˆlander of Frˆlander Entreprenad, sub-contractor scaling and loading in the tunnel, plus the external ground works.

  • The contract for the 1260 m long Hjølta Tunnel on the Botnia Rail Line has been awarded by Botniabanan AB to AF Spesialprosjekt, a subsidiary of the Norwegian contractor AF Gruppen. The contract is worth $5.7M. Work is due to begin in the middle of August and be complete in February 2002. Rock is good quality granite and drill and blast will be used. A coating of shotcrete will be applied to the roof of the tunnel and selective bolting.

    "For some time now AF Spesialprosjekt has considered the Swedish construction market to be part of its home market and we see the construction of the Hj‰lta Tunnel as a test of our capacity to establish ourselves on this market", points out Kasper Nordemalm, President of AF Spesialprosjekt.