SECTOR | RAIL & METRO TUNNELS
6.2 Rescue Shaft 3 RS3 and the exploration and rescue tunnel (ERS) are part of the safety concept for the 2nd core route in the western section above the main station and up to Marienhof station. Rescue shafts connected to the ERS are also planned for the section continuing to the eastern station. With the exception of the upper shaft, RS3 was
constructed using shotcrete under compressed air with a working chamber overpressure of up to 1.7 bar in conjunction with partial groundwater relief. The excavation work for RS3 with upper shaft,
connecting tunnel, shaft head cavern, lower shaft and entrance cavern for the ERS has been completed. In September 2025, work began on the inner lining of RS3, which is scheduled for completion in mid-2026.
6.3 Central access structure - main station As of the end of March 2026, approximately 135,000m3 of soil had been excavated and 24,000m3
of concrete
and 5,000 tonnes of steel had been processed at the central staircase of the main station. The final level, E-6, is currently being excavated, which will mark the maximum depth. This means that the structure is already significantly deeper than the base of the U1/U2 underground station. In the eastern section of the central entrance, the
Top:
Cross-section of the future rescue shaft 3 (RS3) with upper shaft (1), connecting tunnel (2), shaft head cavern (3), lower shaft (4), and entrance cavern exploratory and rescue tunnel (5)
SOURCE: DB INFRAGO AG Bottom:
Excavation in the central access structure at the main station
SOURCE: DB INFRAGO AG
D-Wall for the access structure is located directly next to that of the existing U1 and U2 lines. Due to this proximity of D-Walls, the excavation in the access structure in the area of the U1/U2 was carried out in stages, i.e., a support wedge was provided at levels E-1 to E-4 for stabilisation during the excavation work. This is no longer necessary for levels E-5 and E-6 because they are located below the D-Wall foot of U1/U2. Excavation in this area was carried out in stages so that supporting effects from a ceiling, floor slab or part of the support wedge could be utilised. In addition, props were arranged to partially support
the D-Wall of the access structure on the D-Wall of the metro lines. In this way, displacement of the underground railway structure caused by the excavation was avoided. By mid-2026, most of the preparatory work and
JOINT VENTURE CONTRACTORS FOR MAIN LOTS The joint venture (ARGE) contractors working on the main lots of the project are:
Location: From West via Central Station up to Marienhof: JVs: Joint Venture (ARGE) Tunnel Central Station/Joint Venture (ARGE) Surface West: Wayss & Freytag Ingenieurbau AG, Ed. Züblin AG, Max Bögl Group, Bauer Spezialtiefbau GmbH Location: Marienhof: JVs: Marienhof Joint Venture (ARGE): Implenia Construction GmbH, Munich (37.5%, technical lead), Hochtief Infrastructure GmbH (50%, commercial lead) and Implenia Spezialtiefbau GmbH (12.5%) Location: From Marienhof to the East, including Ostbahnhof: JVs: Ostbahnhof Tunnel Joint Venture (ARGE): Hochtief Infrastructure (Technical lead) and Implenia Construction GmbH (Commercial lead)
installations on the periphery for the ERS in the launch excavation pit will be completed, enabling assembly of the TBM to begin. RS3 will be prepared for passage of the TBM.
6.4 Marienhof underground station Excavation of the 44m-deep construction pit with its five reinforced levels has been completed and the floor slab for Level-6 has been installed. Construction of the connecting tunnel to the existing underground station - using conventional techniques (shotcrete), under compressed air - has been completed. Installation of the 600mm-thick concrete inner shell of the connecting tunnel, constructed insitu under atmospheric conditions, has also been completed. Preparatory work for tunnelling has begun.
16 | May 2026
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