Finnish contractor Lemcon is advancing drill and blast excavations on two tunnels – Bjässholmen and Kroksberg – on the Ådalsbanan rail line on the east coast of Sweden, having recently started the main drives after constructing access adits.
The combined contract value of the tunnels is approximately US$135M, the Bjässholmen project having been awarded in January and the longer Kroksberg job in April by the Central Region of national rail company Banverket. Both are on a new section of line between Härnösand and Veda, south of Kramfors from where the Bothnia rail tunnel projects run to the north (T&TI, February p40) and are to be finished by mid-2010.
The Bjässholmen tunnel will be 3.5km long and have a 3km long parallel service tube, the pilot bore for which has started from the north side. Lemcon has driven 200m of the main tunnel after completing the 500m long access adit in June. The main excavation is progressing at up to 30m per week. At peak, the tunnels will have a maximum of seven faces being advanced through granitic gneiss.
Kroksberg will be a 4.5km long tunnel and is being built approximately 600m to the south of Bjässholmen, also by drill and blast through gneiss in a contract worth US$73M. More than half the excavation of the two access adits has been completed and Lemcon expects to reach the main tunnel location by late September.
A pilot bore is also being driven from the north side but due to other construction works the pilot from the south side will not start until early 2008. In total, the Kroksberg tunnel will have a maximum of nine faces being worked.
The Kroksberg and Bjässholmen tunnels are two of six tunnels with a total length of 11km being built on the new 21km long section of the Ådalsbanan line on the Gulf of Bothnia. Equipment to be used on the main drives include two Rocket Boomer XL4 C30 rigs and a E3 C30 (two boom) from Atlas Copco.
Elsewhere in Sweden, having finished its own Bothnia rail tunnel projects, Lemcon has also just completed another excavation, on the west coast – the drill and blast drive of a 3km long, single bore double-track rail tunnel and its parallel, smaller long maintenance tube. They are part of the 7.5km section of the Torbacken-Hede rail line at Nygard Mountain on the west coast (T&TI, August p5; July 2006 p16) due for completion in 2009.
