The little village of Amsteg sits at the head of a narrow valley where the lowland around Lake Lucerne extends southwards in a narrow tongue surrounded by high mountains. From here the Gotthard pass road south rises steeply through a plunging gorge made passable only by the Devils Bridge built in the 12th century.
Some of the narrow valley bottom between the motorway and river on one side and the village main road on the other, is now the work-site for a big Gotthard service tunnel. It will also be the work-site for the main contractor, who will use the tunnel for twin drives southwards.
Contractor Gebrüder Wüest of Lucerne with Ast-Holzmann Baugesellschaft of Austria is making good progress on construction of the 60m³ cross section 1,800m-long tunnel which runs eastwards to the line of the main train tunnels. It is using an Atlas Copco three-boom semi-automated rig to drill a pattern for the mixed-in-place liquid explosive used for the work. The acrid ammonia smell of about three to five blasts a day testifies to progress of between 10m and 18m daily through the granite on the 7.8m-high tunnel.
The only difficult part was at the portal which is 40m below the old and busy railway line which climbs steeply up the side of the valley. The line’s embankment wall was founded on loose material over rock, and the effect of blasting at the tunnel nose was uncertain. In the event nothing moved, aided perhaps by five big rock anchors holding the nose back just above the portal.
Design was by a group of Swiss firms called IG-GTBn, formed for the Gotthard project and made up from Gähler & Partner, Gruner of Basel, Rothpletz Lienhard and CES Bauingenieur.
Two German reversible-seat Kaelble dumpers are loaded by a Cat 966 at the tunnel face, dropping the rock at a crusher just inside the tunnel mouth, where a Volvo L120 tips it into a small Pegson crusher.
“We move it outside by conveyor to restrict noise,” says Adrian Wildholz, AlpTransit project engineer on the contract. “We have to be sensitive about the village.” All the more so, because it will remain a work-camp for 10 years. Work now being carried out is creating the long-term camp to be used by whichever contractor wins the work. There are to be site offices and accommodation, a new slip road onto the motorway, and a full materials handling facility. The conveyors for the current tunnel spoil handling are being replaced by a much bigger automated system for the main drives to come and their huge volumes of stone.
Swiss firm Aggregat is building a distribution conveyor system which will store stone above tunnel conveyors in the stockpiles. Vibrators will shake stone on to these lower conveyors, as needed, for loading on to trains or for concrete production. “We are using rail to move the stone,” says Mr Wildbolz. “There was already a construction site on this spot used for renovating a hydro-electric plant recently, and it set up a rail line to Erstfeld which we can now extend.” Spoil will be cleaned and re-used, and waste material will be dumped in Lake Lucerne. It is not as environmentally irresponsible a move as it sounds, as it will fill a deep cavity left by years of gravel extraction, restoring fish-spawning grounds.
Related Files
The Gotthard route
