Construction: 1997 - 1998


Limfjord Unterseetunnel Aalborg / DK

Works on the North Sea bed:

Renovation of the Limfjord Tunnel, Denmark

The Limfjord tunnel is one of two road links between North and South Aalborg. The tunnel comprises seven prefabricated segments whose surface was concreted during construction between 1965 and 1969, then lowered onto the fjord bed and connected using construction joints.

The leaking construction joints that occurred shortly afterwards led to seawater penetrating the inside of the tunnel, which required repair.

Job Report – Factsheet

  • Project: Limfjord undersea tunnel, Aalborg, E45, Denmark
  • Contractor: Vejdirektoratet [Danish Road Directorate]
  • Special feature: First use of the Type 4 telescopic robot, concrete strength B75, working 24/7
  • Equipment technology: Telescopic robot and standard robot
  • Unit: KD 412, 1000 bar

Concrete cutting

The twin-tube undersea motorway tunnel was renovated in two construction phases.

The purpose of the renovation was to stop the seawater penetration and to reconstruct the concrete damaged by the highly salty North Sea water. This meant up to 20 cm of concrete had to be removed around the construction joints on walls and ceilings.

Fact: Total 1700 m³ concrete cutting (25 cm thick)

Equipment technology

For ceiling heights exceeding 5 m, cutting with conventional robots would not be possible. Telescopic robots designed in-house specifically for this project enabled efficient mechanical cutting. Three of these telescopic robots each with a 450 kW pump unit were used.

A standard robot with a corresponding pump was also used to cut the walls of the entire tunnel surface to a height of 3 m and a depth of 10 cm.

Continuous 24h operation was required due to the short construction time. A standby unit was also reserved throughout the entire construction period to ensure continuous working capacity during service and maintenance works to the pumps.


Despite a concrete grade equivalent to B75, the second construction phase was completed within eight weeks. A total of 1500 m³ concrete was cut during this time.

This type of removal rate 2000 km away from the company head office is only possible through perfect planning in combination with high-performance technology and highly motivated, trained personnel.

Working under the highest quality criteria

Renovation of the P6 multi-storey car park – Zurich Airport

With more than 26 million passengers every year, Zurich is the number 1 airport in Switzerland. The airport is also an international player in terms of quality. Therefore, the chloride-damaged surfaces of the P6 multi-storey car park were overhauled to the highest standards, including the consistent use of certified particulate filters.

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Work on a European transport hub

Renovation of Felperbrücke - A13 Brenner motorway

The renovation works on the high-traffic Felperbrücke on the Brenner motorway were completed in three construction phases – with two-way traffic throughout – and posed great challenges to man and machine due to the tight interim and final deadlines.

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Renovation of the water-side dam wall

Maintenance of Pöhl Reservoir / Saxony

The structure required restoration due to the severely damaged concrete surface of the water-side dam wall. The remedial works for the dam wall were scheduled in two stages. Firstly, large areas of damage, weathered old concrete were removed by high-pressure water blasting. Secondly, a 20 cm-thick shotcrete facing formwork was constructed.

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