Virtual Congress for Swiss discussions Jun 2020

Roland Herr for TunnelTalk

"For the first time, we are running our conference purely digitally," said Stefan Maurhofer, President of the Swiss Tunnelling Society, in a video recorded in an empty hall in Lucerne, and simultaneously on numerous connected screens all over the world. The colloquium was broadcast as a live stream in the afternoon with questions sent via the broadcast connection and answered by the speakers at the end of the session. Videos of the presentations were available free-of-charge on the Swiss Tunnelling Society website with a PDF of the conference proceedings also available for download for the first time. It was a pity that this time the presentations were mostly in German and not simultaneously translated into English as usual. The only downside of the virtual experience was the lack of stimulating discussions with colleagues, the personal exchange and the establishment of new contacts. Nevertheless, we all have to adjust to the fact that large industry conferences will only take place digitally for the foreseeable future.

The conference programme focused on numerous large tunnel structures currently being planned and under construction in Switzerland, with presentations on the Gotschna, Albula II, Bypass Luzern, LEB Lausanne, RBS Bern and Ligerz projects, and the current status of the FCC project at CERN. Reports were given also on major European projects including the second S-Bahn core route in Munich Germany, the Koralm rail link in Austria, the Milano-Genova high capacity railway project in Italy, the Grand Paris metro expansion project in France, and the Mont Cenis baseline tunnel on the Lyon-Turin rail link between France and Italy.

Long-term expansion of the Swiss rail network

"The Swiss rail network, at approximately 3,000km long, is one of the busiest rail networks in the world,” began Andreas Brunner, member of the Infrastructure Management of the Swiss Federal Railways (SBB). “Of the 383km of the route in 282 tunnels, the shortest is the 7m Moutier III tunnel and the longest is the twin tube 57km Gotthard baseline tunnel. The 15.4km long Ceneri base tunnel, the 3.1km long Eppenberg tunnel and the 2.7km long Bözberg tunnel are currently under construction. In 2019 alone, CHF 65 million (about €60.5 million or USD$68.7 million) was invested in the renewal and maintenance of tunnels.

Rail projects currently under construction (red) and in the planning (purple) in Switzerland
Rail projects currently under construction (red) and in the planning (purple) in Switzerland

By 2035 construction is planned for:

  • The new double-track Ligerz tunnel during 2021 to 2026;
  • Renovation of the Hauenstein base tunnel between 2023 to 2027;
  • Extension of the Zurich-Stadelhofen rail line with a fourth station track and a second Riesbach tunnel for 2026 to 2035;
  • The additional 9km long double track Brüttener tunnel planned for 2026 to 2035;
  • An additional Zimmerberg Tunnel II relief tunnel, in concept study until the end of 2020 for construction between 2026 to 2035;
  • The Neuchâtel-La Chaux-de-Fonds tunnel for 2028 to 2035 and
  • The expansion of the Geneva underground station (2028 planned until 2035).
Lucerne Bypass longitudinal section
Lucerne Bypass longitudinal section

Lucerne bypass

To improve road traffic in the Lucerne metropolitan area, the construction of twin tube tunnels with two lanes in each direction is planned as part of the overall bypass system for the city from 2025 to 2037. Also, several existing tunnels are being extensively repaired. Thomas Kloth from the Federal Roads Office (FEDRO) described the complex 3.8km long project that will pass under the River Reuss and the city center. A closed shield or an open gripper TBM of about 13m diameter will excavate about 3km of the new link under an overburden of 25m to 100m with cut-and-cover at each end (Fig 2). The TBM tunnel will have a double lining of an initial 30cm thick segmental lining and an 30cm thick full seal inner lining. A third tube will be added to an existing cut-and-cover tunnel as part of further expansion project in the northern area. The costs for the entire bypass system is about CHF 1.8 billion (about €1.68 billion or USD$1.89 billion) without the restructuring measures.

Route of the second core S-Bahn in Munich
Route of the second core S-Bahn in Munich
Connection of the rescue tunnel with main tubes to the station
Connection of the rescue tunnel with main tubes to the station
Credit: DB AG/Fritz Stoiber Productions GmbH

Second S-Bahn core route Munich

The Munich S-Bahn system is one of the largest current projects in Germany. The new core route will augment the existing route that went into operation for the 1972 Olympic Games in Munich, and passes under the inner city from east to west, and is some 10km long between the Laim train station in the west and Leuchtenbergring in the east. Albert Wimmer from Deutsche Bahn Netz AG explained the 7.1km long underground center piece of the €3.8 billion ($4.3 billion) project (Fig 3). Due to the numerous supply lines and the existing first core route, the new tunnels must be built one level below these structures with the new stations at a depth of 35-40m. The two tunnels are to be excavated by two 8.4m diameter TBMs advancing from the east and west portals, under an overburden of 7m to 40m and erecting a segmental lining of 45cm thick as they advance.

A special feature of the project is the alternative rescue concept made possible by an amended European Union directive, which provides for a central third escape and rescue tunnel instead of the rescue shafts that have a massive impact on the inner-city infrastructure. The rescue tunnel with an outside diameter of 4.7m is excavated before the main running tunnels and also serves as an exploratory tunnel (Fig 4).


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