BY THE END of 2005 all civil engineering work for the Lötschberg base tunnel project in Switzerland will have been completed. Installation of track and other railway equipment is now forging ahead to prepare the 34·6 km tunnel for the start of commercial operations in 2007.
The biggest milestone was passed on April 28 2005, when tunnellers celebrated the final breakthrough between the intermediate access points at Ferden and Mitholz. The civil contractors at once began to move their equipment to free the worksites for installation of track and other railway equipment. No less than 65 km of conveyor belts had to be taken out of the tunnels, while offices and accommodation containers had to be dismantled and removed.
Around two-thirds of the railway equipment has to be installed from the southern portal at Raron, with the rest being fitted from the northern portal at Frutigen near Kandersteg. Exactly half the 49 km of track has been installed so far, together with several kilometres of communications cable. Tracklaying in the southern part of the tunnel will be finished by February 2006, and in January the first track will be installed at the northern end. Test running is due to begin in the spring in the southern section of the tunnel.
The tunnel consists of two single bores south of the Mitholz access, but to reduce the capital cost the northern section has only a single bore, so the parallel Kandertal exploration drive is being fitted out as a service tunnel. Another economy measure means that track is not being laid in both tunnels initially. Both bores will be fully fitted between Raron and Ferden, but from there to Mitholz track is only being laid in the eastern tunnel. Track will not be laid in the second bore until a later date.
A separate single-track tunnel has been built from Steg to the west of Raron, which will allow direct access for trains to and from the Valais, but this too will not be fitted out until later.
Fitting out underway
The portal area at Raron was handed over for fitting out at the end of November following completion of the last portal arch structure in mid-September. Activity now centres on the section between the portal and the northern bridge over the Rhône. The west tunnel has been in the hands of the railway contractors for some time, and the teams began work in the east tunnel in September.
Near the northern portal at Frutigen, a maintenance and emergency centre is under construction, while the first of two special emergency trains, one owned by SBB and one by BLS, has been completed by Windhoff.
A considerable amount of related work has been taking place near Frutigen, including the construction of a 2·6 km cut-and-cover tunnel at Engstlige. This structure is now complete and recultivation is underway. Sound barriers at Tellenfeld between the Engstlige tunnel and the base tunnel portal are nearly complete. The alignment of the main line in the approach area has had to be moved, necessitating temporary single-line working, but this work was completed last month and both tracks were restored to full working order on November 11.
Working south from the Mitholz intermediate access point, the final concrete for the tunnel as far as the boundary with the Ferden section has been placed. After that, the tunnellers completed work on the inner lining of the remaining 230 m that passes through a zone of carboniferous rock where special high-strength concrete was needed; the number of rock bolts per metre was increased from four to 35 and in places the inner lining is up to 1·5 m thick.
To the north of Mitholz, the section was handed over to the general contractor ARGE Bahntechnik at the end of September, after cleaning and all the drainage pipes had been flushed. This had proved quite difficult as the mobile cleaning units had been deployed elsewhere to cope with the aftermath of serious flooding affecting the surrounding area.
At the Ferden intermediate access point, dismantling of the formwork rigs and their removal from the tunnel has been completed, the air intake system and airlock have been dismantled, and foul air is now being extracted via the Raron east tube rather than the shaft at Fystertellä. Final works are in hand on the air intake system, and most of the concrete for the linings in the cross-tunnels is in place. In the lateral adit, dismantling of the pumping stations has begun.
Track and signalling
At the end of August trials began with Level 2 ETCS equipment on a test track at Dottikon near Lenzburg. This allowed teething troubles to be dealt with. Should there be difficulties with ETCS, a prudent decision was taken by the Swiss transport ministry to install a back-up system in the form of conventional signalling at each portal, although this would of course severely limit the tunnel's capacity.
Signalling and train control equipment will be located at eight locations along the tunnel. The equipment is installed in 136 stainless steel containers to protect it from heat and damp, with testing carried out in an assembly hall in Bern before the containers are shipped. The first was moved from Bern to Raron on September 30, ready for installation at Lötschen, near the southern portal.
Electrical and mechanical equipment is being supplied and installed by a joint venture of Rhomberg Bahntechnik and Zschokke-Locher which has a SFr650m contract. The companies are responsible for cabling, OHLE, traction power supply, ventilation, telecommunications, optic fibre links, and the permanent way. Its remit also covers lighting, fire detection and suppression equipment, gas and moisture detectors, video systems, doors into the cross-passages and control centres, together with power supplies.
A total of 57 km of low-vibration ballastless track with a design life of 50 years is being laid, plus 5·9 km of conventional ballasted track. Rhomberg Bau AG, a subsidiary of Rhomberg Holding GmbH of Bregenz, is general contractor for the trackwork and is taking full responsibility for design, installation and approval procedures. Total value of the track contract is SFr147m.
Some parts of the tunnel were built with a TBM, and other sections using drill-and-blasting methods. This means that there are two tunnel profiles requiring different trackforms.
For drill-and-blast sections the track has a cast concrete base 510 mm thick. Single-block sleepers in rubber boots are accurately positioned to support each rail at 600 mm intervals, and a second layer of concrete is then poured in. Cant of up to 50 mm is allowed for when the sleepers are positioned.
For TBM sections the deep lower base is not needed, but the same technique of rubber-booted sleepers in a layer of cast concrete is used. Up to 62 mm of cant is possible. To ensure an accurate alignment, Rhomberg Bahntechnik uses its own system called Hergie, which achieves the required tolerances. UIC60 rails to the S900A quality standard are laid at an angle of 1:40.
In turnout areas, the Phoenix track system developed by Austrian Federal Railways is being used.
The tunnel is due to open for freight traffic running at up to 160 km/h in May 2007. This will give six months of operating experience before passenger trains start to use the base tunnel at up to 250 km/h with the European timetable change in December 2007.