A JV of Implenia and Hochtief, with Implenia in the technical lead role, has been awarded the Lot VE41 on the second main rail line under the city of Munich in Germany. The €400 million (US$455 million) contract is for excavation of the Marienhof Station and connecting tunnels directly behind the Munich City Hall.

Section of the new S-Bahn for Munich

Work comprises excavation of a large box structure to accommodate 210m long platforms at a depth of about 40m. Work is due to start by mid-year 2019 and be complete by 2026.

German national rail authority Deutsche Bahn is investing €3.85 billion (US4.38 billion) to build the 10km long Second Core S-Bahn project by 2026. The underground portion involves major tunnel construction, including twin 7.5m i.d. running tunnels to connect the city’s three main Hauptbahnhof, Marienhof and Ostbahnhof railway stations.

The Marienhof Station contract award follows recent awards of the Hauptbahnhof Lot VE30 to a JV of Wayss & Freytag, Zublin, Max Bogl and Bauer Spezialtiefbau, which also is contractor for the adjacent surface works package.

In the city of Munich, Germany, a major capital investment programme is underway to construct a second S-Bahn route beneath the city centre. The new 10km route includes a 7km underground section to link the city’s three main Hauptbahnhof, Marienhof and Ostbahnhof railway stations. The running tunnels will pass beneath the U-Bahn metro lines and will reach depths of more than 40m near Hauptbahnhof.

Second S-Bahn route under Munich city centre

The first two main contracts on the project, covering the western and much of the middle sections, have been awarded to JVs of the same partners– Wayss & Freytag, Zublin, Max Bogl and Bauer Spezialtiefbau. The contracts cover the surface and the first of the tunnel lots. Combined contract value for the two lots is about €865 million (US$980 million) with Wayss & Freytag leading the JV on the Lot VE30 underground works, valued at €676 million, and Zublin heading the team on the Lot VE10 surface and portal works in the west, valued at €189 million. Construction started on preparatory works for the surface VE10 contract during 2018.

Near the Hauptbahnhof, boreholes and groundwater investigation have been underway during 2018 in advance of the VE30 underground works, due to get underway in 2019. TBMs will drive running tunnels either side of the Hauptbahnhof while open face, compressed air conditions will be established to excavate the new infrastructure below the station. In a statement, Project Manager Markus Kretschmer for the client, Deutsche Bahn (DB), said: “After almost two years of preparatory works, we can initiate the second phase and start the main construction in the coming year.”

New S-Bahn Hauptbahnhof Station

Extensive ground investigations have also been underway in the area around Marienhof station. Contract award is expected soon for the main tunnelling and underground package or Lot VE41, the second on the overall project, confirmed a DB spokesperson. Procurement for the third and last main construction work at the station, linking tunnels and other works, including at Ostbahnhof, is still underway. The DB spokesperson said: “The tendering procedure for the tunnels east of Marienhof has not started yet.”

In total, the project will involve about 14km of slurry shield drives as well as cross passages, sections of shotcrete works and about eight shafts, explained Albert Wimmer, team leader for tunnelling on the project for DB. The underground works will be located in tertiary sediments of fluvial and lacustrine origin, overlayed by quaternary sediments. The tertiary sediments consist of clays, silts and marls, alternating with mica-rich sands. The quaternary sediments are glacio-fluvial gravels.

A number of tunnelling techniques are to be employed across the project. All slurry TBM tunnelling for the 7.5m i.d. segmental lined running tunnels will be under groundwater levels with pressures up to 4.5 bar. The emergency escape tunnels and the station platform tunnels are to be excavated using open face NATM sequences, in part supported by compressed air conditions and in part using ground freezing, TunnelTalk was told.

The €3.85 billion (US$4.36 billion) project will be the second S-Bahn line running through the heart of Munich, and also passing through Hauptbahnhof, the Marienplatz area and finishing at Ostbahnhof. With only half the number of stations as the first line, the major new route will offer short travel times across the middle of the city and is planned to come into operation in 2026.

TBM u-turn at Filder Tunnel

In the meantime, and after manoeuvring an underground u-turn,

The 10.82m diameter multi-mode Herrenknecht TBM in Stuttgart started its fourth and final drive on the twin tube Filder Tunnel as part of the high-speed rail project being developed by \ DB. Construction by the Porr, Hinteregger, Ostu-Stettin and Swietelsky JV began in 2014 and called for carefully staged excavation of a total of 19.1km of single track running tunnels with cross passages and caverns. Two initial TBM drives, in closed EPB mode were excavated on the south side of a geological transition that cuts across the alignment and finished at a cavern in the transition zone. TBM drives 3 and 4 are advanced in open mode on the other side of the transition cavern.

Drive 3 was completed in late summer with the TBM advancing into a crossover cavern near the Stuttgart main railway station that was excavated large enough to receive and manoeuvre the TBM through the two 90 degree turns from one tube. Drive 4 to complete the parallel 3.8km tunnel back to the transition cavern is expected to hole through in summer 2019.

Elsewhere on the Stuttgart-Wendlingen-Ulm rail project, DB reports that TBM excavation on the Albvorland contract, the last major tunnelling section to get underway, is advancing well and approaching two-thirds complete. Contractor Implenia began the twin 8.16km drives with two 10.82m diameter Herrenknecht EPBMs about 13 months ago.