There was a double celebration in Switzerland on 31 October, with the TBM start-up on the Moutier tunnel, and the groundbreaking ceremony on Raimeux tunnel, both on the highway A16 Transjurane.
Marti Tunnelbau AG celebrated with client, Direction des travaux publics du Canton de Bern, and construction engineer GVH and BG.
The US$66.4M Moutier tunnel consists of a 1,140m twin-bore tunnel, driven by a 11.7m diameter Herrenknecht TBM through the molasse Alsacienne. Owned by Marti Tunnelbau, it’s the fourth outing for the TBM, having already bored the Grauholz, Pomy and Gorgier tunnels in Switzerland.
It will be lined with 280mm thick 5+1 precast segments which are being produced 30km away in the Marti factory in Klus. Following the drive, a water proofing membrane and the 310mm thick final lining will be placed. Construction should be completed in early 2005.
The tunnel replaces an otherwise 6% slope that would have prevented a 1st class highway classification for the road, and is cheaper than the combined costs of land purchase and road construction.
Following the TBM start on the Moutier tunnel, the client representatives, guests and workers travelled to the construction site of the 3,211m long Raimeux tunnel, where they witnessed the breakthrough – 850m in from the south portal by a roadheader.
Changing geological conditions, including limestone, required excavation by both roadheader and drill and blast from the north portal. From the south portal a pipe umbrella support system was used.
The US$86.3M Raimeux tunnel has a cross section of 68m2 to 112m2. A 250m deep ventilation shaft was constructed by raise drill, 1,060m from the north portal, which was widened from top-down to a diameter of 5m.
Construction work on the two-lane Raimeux tunnel will continue with further excavations in the molasse sections, concrete work for the invert, waterproofing and concrete lining. Construction will last until the end of 2004.
Marti Tunnelbau AG is the main contractor and lead sponsor for both tunnelling projects.
