Securing Hansakai - Stralsund harbor island

Between June 2021 and April 2023, Ed. Züblin AG, Engineering and Port Construction Division of the Northern Directorate, carried out a technically demanding major hydraulic engineering project on behalf of Stadterneuerungsgesellschaft Stralsund mbH to secure the Hansakai on the northern harbor island. The aim of the measure was the fundamental renewal of the dilapidated embankments and the creation of a safe, load-bearing basis for the subsequent design and functional upgrading of the open spaces around the harbour square.

The project comprised several sub-zones, including berth 6, the harbour office and the slipway. In all areas, existing, damaged quay edges had to be dismantled and replaced with modern sheet piling constructions. A total of 183 meters of new sheet piling was erected, including both anchored wave walls and unanchored box pile walls. These were a central structural element of the shore restoration and now form the new load-bearing harbour line.

Extensive demolition work was required at the start of construction. A total of around 800 m³ of concrete and reinforced concrete was removed. The dismantling of a 45 meter high lattice mast was also one of the more complex tasks. The new foundation and anchoring system, which comprises 114 deep-reaching micropiles, was then installed. They serve both to tie back the sheet pile walls and to transfer the load for the newly created staircase and pylon foundations.

The new water staircase was a particular design focus of the project. This reinforced concrete structure, around 11 meters wide, combines functional requirements such as accessibility and shoreline use with high architectural standards. The cladding with precast concrete elements in outstanding exposed concrete quality contributes significantly to the visual and urban development enhancement of the harbor area and represents a new, distinctive eye-catcher. The technical services for the project encompassed a wide range of hydraulic engineering and solid engineering work. These included sheet piling constructions with a total mass of 666 tons, the installation of 616 m³ of unreinforced concrete and 145 tons of reinforcing steel. In addition, around 10,000 m³ of soil material was moved for backfilling and stabilization measures. A continuous reinforced concrete beam over a length of 190 meters as well as scour protection over an area of 550 m² complete the complex bank protection system.

The construction method was characterized by solid construction in combination with a high proportion of hydraulic steel construction work. This included flame cutting, welding and the assembly of custom-made belt constructions. The work had to be carried out with extreme precision due to tight dimensional tolerances and strict requirements for the exposed concrete quality.
The contract value was 3.7 million euros. With the completion of the securing work, a decisive contribution was made to the revitalization of the northern harbour island. The project combines sophisticated civil engineering, hydraulic engineering expertise and design quality. It creates the necessary basis for a permanent, versatile and high-quality urban development use of the harbor area. Due to its complexity and precision, the project is considered exemplary for modern shoreline redevelopment in a maritime environment.