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HOCHTIEF Building · Project Example

Rastatt Tunnel, upgrade and construction of Karlsruhe-Basel section

Country Germany
Client DB Netz AG
Construction period 2014 - 2018
Contract volume EUR 312 million

The Rastatt Tunnel is part of the Deutsche Bahn’s upgrade and construction of the Karlsruhe-Basel rail line. Once completed, the presence of rail traffic in the Rastatt urban area will be significantly reduced as much of the freight and long-distance traffic will run through the tunnel.

HOCHTIEF has been building the over four-kilometer-long shell structure of the Rastatt Tunnel since 2014 as part of a joint venture. Construction work is primarily focused on two parallel, single-track main tunnels that run directly beneath the Rastatt urban area, with little cover in places. The main tunnels are being driven at staggered intervals using tunnel boring machines (TBMs) and will be fitted out with single-leaf lining segments. As a preliminary measure to the tunnel-driving work, extensive ground-freezing is being carried out—both in the area of low tunnel cover in a nature reserve, and where the tunnel runs beneath existing Rhine Valley rail track.

Our contract also includes the construction of the two trough sections, a utility shaft, and an operations building.

Special characteristics

  • Structures are built at great depth and in permeable soils with high groundwater levels, which may not be lowered.
  • The construction process allows for the time-delayed use of two tunnel boring machines (TBM).
  • The tracks of the Rheintalbahn are tunneled under with a very shallow overburden, passing through the 200 m long and two meter thick ring-shaped freezing zone.
  • Preliminary assessments on the impact of the foundation ground freezing on the quality of the bentonite grout during the breaking through with the TBM.
  • The TBM is started from a diaphragm wall pit using the tried and tested HOCHTIEF “flying start” system (hydraulic TBM launching rig method).
  • The impact of the advance on the ground surface is monitored in real time via the IRIS tunnel monitoring system.

Construction methods

  • The two single-track main tubing tunnels feature a single-case design.
  • The trough structures and the tunnels in open construction are to be built in watertight excavation pits with sheet piling, as well as partially diaphragm and bored pile walls and deep-anchored underwater concrete bases.
  • The 8 connective structures between the main tubbing tunnels are advanced using the NATM (New Austrian Tunneling Method) driving method, while being protected by the freezing of the ground with salt brine.
  • Special segments with integrated covered steel openings with screwed-on lids (patented HOCHTIEF system) are installed at the segment openings to the connecting structures.


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HOCHTIEF Infrastructure GmbH
Deutschland Südwest
Lyoner Straße 25
60528 Frankfurt am Main • Deutschland
Tel: +49 69 7117-0