“Kriegsstraße” tunnel shell is in place: ZÜBLIN-led consortium completes complex large-scale project in Karlsruhe on schedule

• Ed. Züblin AG and Schleith GmbH hand extended shell for street tunnel over to KASIG after four years and three months construction time
• 1.6 km tunnel to reduce vehicle traffic in the centre of Karlsruhe over the long term
• Traffic scheduled to open in mid-December following overall completion of technical works

The core of a major infrastructure project in the heart of Karlsruhe has been successfully completed on time. Precisely on schedule, today consortium leader Ed. Züblin AG and its partner Schleith GmbH handed the extended shell of the 1.6 km “Kriegsstraße” road tunnel over to Karlsruher Schieneninfrastruktur-Gesellschaft mbH (KASIG). Following a construction period of four years and three months, the two tunnel lanes have been covered in asphalt, completing the complex construction of the shell. Once the technical works that now follow are completed, the tunnel and new above-ground light rail line are to be opened to traffic in mid-December. Following a separately constructed tram tunnel, it is the second part of the “Kombilösung” public transport infrastructure project, which will provide Karlsruhe's city centre with a new component for an efficient local public rail network and sustainably reduce the volume of traffic.

Outstanding, constructive cooperation a guarantee for success “Reciprocal, open, solution-oriented communication was a guarantee for success,” says Frank Nenninger, technical director at KASIG, summing up the completion of the work by the ZÜBLIN-led consortium. “We are proud to have mastered this technically and logistically demanding project successfully and on schedule. Despite disruptions in the construction process caused by the coronavirus pandemic, we even completed the extended tunnel shell a good week ahead of the deadline that was originally set," says overall project manager Roman Kühn from the leading civil engineering division of the ZÜBLIN subdivision in Karlsruhe. With “highly fragmented workflows” due to the constant change in provisional traffic routing, the logistics were the biggest challenge for the project team: “Over the past year, with ten cranes, we were operating in every construction site simultaneously," Roman Kühn reports. As a guarantee for success, he mentioned the close synchronisation of every trade group with the use of LEAN methods and, in particular, the outstanding communication and cooperation with the client: “The extremely constructive and always progress-oriented coordination with KASIG was an essential factor for the success of this construction project," Roman Kühn sums up.

City-centre location a complex challenge

The new tunnel relocates Karlsruhe's main traffic axis on Kriegsstraße between the Ludwig-Erhard-Allee junction and the Karlstor underground. The Ed. Züblin AG-led consortium constructed it as a cut-and-cover in a synthetic fibre-reinforced concrete frame: the works were divided into ten individual sites with waterproof excavation pits of up to nine metres deep that were covered in concrete and later sealed again with a lid. The city-centre buildings directly adjacent, the dense traffic flows partly crossing the route and the high groundwater level made the construction project a complex challenge. The ZÜBLIN project team was supported until the end of 2020 by Züblin Spezialtiefbau GmbH, whose expertise ensured, among other things, the waterproofing of the excavation pit.

Further details on this central infrastructure project in the city of Karlsruhe can be found at: www.diekombiloesung.de

Facts & Figures

ZÜBLIN UNITS:

Ed. Züblin AG, Subdivision Karlsruhe, Civil Engineering

Züblin Spezialtiefbau GmbH

CONSORTIUM:

Ed. Züblin AG (67%)

Schleith GmbH (33%)

PROJECT SCHEDULE:

4/2017–7/2021

CLIENT:

Karlsruher Schieneninfrastruktur-Gesellschaft mbH (KASIG)