Rail access

Because of the great depth of the running tunnels at Sedrun (nearly 1 km beneath the level of the FO line), it is impossible to provide the kind of direct rail-based excavation used on Channel Tunnel. With the need to minimize environmental impact, provision has been made to transport as much material by rail as possible. A 2.3 km branch has been built from a junction with the Furka-Oberalp Railway to the east of Sedrun station. This rack-equipped line drops down sharply into the Vorderrhein valley below the town to sidings alongside the river, serving the construction depot at the mouth of the Sedrun adit.

At the same time, SFr 120 m has been spent on upgrading the FO and RhB route from Chur to Sedrun for construction traffic, including signaling, power supplies and extra passing loops. The objective is to bring 90 % of materials for the tunnel by rail, most of which will be cement. Much of the tunnel spoil will be reused as aggregate for concrete for the tunnel, and for strengthening a number of local bridges, so very little will be brought out by rail.

Accommodation for the 130 workers building the shaft and a site office and exhibition centre have been provided a little below Sedrun town, but as it is a considerable drop down into the valley floor construction site, an SBB-owned funicular railway has been installed to transport workers up and down the hillside.

Workfaces

Once the shaft has been sunk into the rock down to the altitude of 547 m above sea level, expected by December this year, the job of creating workfaces for the running tunnels will begin. First, a cavern will be built at the bottom of the shaft to provide logistic space for moving equipment and spoil, and ASS is contracted to have this ready by August 27 next year.

Work will then move on to create the connecting passageways and initial tunnel sections, ready for the start of tunneling through the difficult geology to begin in early 2002. Working conditions will also be unpleasant – the high ambient rock temperature combined with water seepage will make the workface hot, humid, noisy and muddy. Adequate ventilation and rotating shift working will help minimize prolonged discomfort, but if necessary workers will be supplied with special water-cooled worksuits. Drainage will also be difficult, as water must not only be pumped up the access shaft, but also pumped uphill from the workfaces.

The twin tunnels and cross-passages running 2.2 km north descend at a grade of 0.4 %, and are due for completion by 2003; these should connect with an 11 km drive from the Amsteg access sometime in 2006.

Meanwhile, the Sedrun workers will have opened a second face, boring the tunnels south. A 4.5 km section will be dug by 2005, initially climbing at 0.4 %, it will then drop at 0.7 %, connecting with the 15 km northwards drive from Faido in 2007. Fitting out will have already begun on the outer ends of the tunnel, where construction will be easier and consequently faster. It will move to the central section later – this work should be completed in 2010, ready for opening of the whole base tunnel in 2011.