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The Building and Civil Engineering department, together with the Schlierschied branch, has been awarded a contract by Basalt Actien-Gesellschaft for the construction of a tunnel structure with a contract volume of around 2.4 million euros. The construction period is scheduled to run from July 2026 to February 2027.
The planned expansion of the extraction area of the Ellenberg extraction site of Süddeutsche Hartsteinwerke (a branch of Basalt AG) in a north-easterly direction requires the construction of a new tunnel to pass under the K7 district road. The tunnel, which is to be built using the cut-and-cover method, has a length of around 51.5 metres, a clearance height of 7.85 metres and a width of 14.80 metres. It will be used exclusively by Basalt AG works vehicles and will therefore have a ballast carriageway.
During the construction phase, the K7 will be completely closed and dismantled; diversions are only planned to a limited extent. Once the structure has been completed, the district road will be fully restored. The structure will be constructed as a water-impermeable concrete structure in accordance with the relevant regulations. This includes a 1.20 m thick floor slab and walls, a ceiling up to 1.41 m thick, bituminous sealing of the tunnel ceiling and walls and a 10 cm thick protective concrete layer over the sealing.
To protect the surroundings and provide visual screening, 2.50 m high gabion walls will be erected on top of the structure to provide privacy. All exposed concrete surfaces are produced in high exposed concrete quality.
