Erstatningshavn Færgehavn Nord: a temporary harbour built with ArcelorMittal steel sheet piles

Due to the construction of the Nordhavn Tunnel underneath Svanemølle Bay in Copenhagen, a large part of Svanemølle Harbour has to be temporarily closed. Harbour facilities and about half of the floating docks have had to be moved to the nearby Færgehavn Nord temporary harbour. In 2021, ArcelorMittal supplied approximately 1190 tonnes of AU18 sheet piles in steel grade S355GP with lengths ranging between 7m and 13m for the 450-metre-long, new breakwater. About 65 tonnes of 10-to-10.7-metre-long GU12N in S355GP were also supplied for a new dock at Svanemølle Harbour.

Detailed information

The Vejdirektoratet (Danish Road Directorate) is in charge of the construction of the Nordhavn Tunnel project in Copenhagen. It is an essential element of the planned urban development of Nordhavn, a new urban area which will eventually have 40 000 inhabitants and as many jobs. The tunnel is being built on behalf of the Copenhagen Municipality, who is financing the project together with By & Havn and the future company for Lynetteholmen (a new island project off the coast of Nordhavn).

The project entails the construction of a 1.4-km tunnel built with the cut and cover method underneath Svanemølle Bay. Upon completion, the ownership of the tunnel will be handed over to the Copenhagen Municipality.

A temporary harbour during tunnel construction

As the tunnel is being built with the cut and cover method, it requires the temporary closure of a large portion of the Svanemølle Harbour. While the tunnel is under construction, harbour facilities and about half of the floating docks have been moved to the nearby Erstatningshavnen Færgehavn Nord – the Færgehavn Nord Replacement Harbour. The temporary harbour included the construction of floating docks for berthing approximately 600 boats, a new breakwater, and a new crane area. The existing dockside walls, which were kept, consist of steel sheet piles with one anchor level that was constructed in the 1960s.

ArcelorMittal supplied 1190 tonnes of AU 18 sheet piles in steel grade S 355 GP with a length ranging between 7m and 13m for the breakwater and some 65 tonnes of 10m-to-10.7-metre-long GU 12N in S 355 GP for a new dock at Svanemølle Harbour.

The budget of the entire tunnel project is 3.4 billon DKK (approx. 455 million EUR) and the tunnel should be ready for traffic in summer 2027, with an expected traffic of 8200 vehicles per day. The construction of the Færgehavn Nord Replacement Harbour was carried out as a traditional design-bid-build contract, whereas the Nordhavn Tunnel is being carried out as a design & build contract.

The tender for the replacement harbour was issued in April 2021, and the construction company Munck was awarded the contract on September 2021 to build it for the amount of 75 million DKK (approx. 10 million EUR).

Breakwater design and installation

The curved breakwater has a combined length of 450 metres and has been designed and executed as a double wall cofferdam with the front sheet piles installed (on the sea side) with a top level at -2m and the back sheet piling installed with a top level of +2m. The steel sheet pile walls are anchored at the elevation -4m with a tie rod of diameter 40mm in steel grade S 500 spaced 1.5m apart. After the piles were installed, the space between the two sheet pile rows of the cofferdams was filled with sand and three different types of rock elements on top.

The sheet piles were driven with an ICE 14RF high frequency vibratory hammer with a variable moment of 14 kgm and a centrifugal force of 812 kN, an ICE 28RF with a variable moment of 28 kgm and a centrifugal force of 1 600 kN, and an impact hammer of 6t mounted on a Junttan PM 20 telescopic rig. The short AU 18 sheet piles under water were driven with a DH-35 Movax piling hammer (ram weight of 3.1t and an impact energy of 0 -35 kNm) mounted on a Hitachi excavator.

A small dock for lifting the boats was built at the Svaneknoppen section of Svanemølle Harbour and has been in operation since April 2022. The double wall cofferdam was built at the entrance of the temporary harbour. The existing seabed level varies from approximately -6m to -8m. The upper layers in which the sheet piles were driven consist typically of fills, gyttja, clay, clay till, silt, sand, sand till, gravel, limestone, limestone till, etc.

The execution of the breakwater started in October 2021 and finished in July 2022 when the effective move of the boats started.

Project information

  • Copenhagen
  • Denmark
  • 2022
  • Project owner:
    Copenhagen Municipality
  • Project management:
    Vejdirektoratet
  • Designer:
    Ramboll
  • Contractor:
    Munck Havne og Anlæg A/S
  • Text:
    ArcelorMittal Sheet Piling
    Constructalia
  • Images:
    Munck Havne og Anlæg A/S