The tunnel under Świna, commissioned on June 30, 2023, connecting the islands of Uznam and Wolin in Świnoujście, is the longest underwater crossing in Poland. Thanks to this investment, the city gained a permanent road connection with the rest of the country. Advanced technologies were used in its implementation, e.g. an innovative hybrid intumescent steel coating Nullifire SC902 from CPG Europe.

The investor of the tunnel was the Municipality of Świnoujście, and the project manager was the General Directorate for National Roads and Motorways, Szczecin Branch. The project was supervised by SWECO/Lafrenz and the contractor was the PORR/Gülermak consortium. The cost of building the underwater crossing in Świnoujście amounted to over PLN 900 million, of which PLN 775 million was co-financed by the European Union, and the rest came from the city budget.

The road connection between the islands of Wolin and Uznam opened in June 2023, where the administrative and service centre and the seaside district of Świnoujście are located, which is a great convenience for residents and tourists. Previously, only ferry crossings operated, which did not have sufficient capacity, which was associated with long waiting times for the ferry, and were dependent on weather conditions.

The longest underwater crossing in Poland, including access roads, is almost 3.2 km long, with its main part, i.e. the tunnel drilled under the strait, approx. 1.5 km long. At its deepest point, the tunnel is 39 meters below the surface of the Świna Strait. The tunnel is a single tube. The roadway is 7 meters wide (two 3.5 m wide lanes – one in each direction) and emergency lanes are about 2 m wide.

The drilling of the tunnel took place from March to September 2021. It was started on the island of Uznam and then drilled under the Świna to the island of Wolin. For this complex operation, a TBM weighing 2,740 tons, 105 m long and 13.4 m in diameter was used. Simultaneously with the drilling, the TBM machine laid the concrete rings of the tunnel casing. Each was composed of several segments. One ring weighed 100 tons. In total, the TBM machine arranged 764 such rings.

Further work included construction of the roadway and ceiling, pouring asphalt on which vehicular traffic takes place, implementation of installation and finishing works, including aluminium panels installed on the ramp and in the tunnel.

As part of the fire protection of the tunnel in Świnoujście, over 1,000 steel anchors installed in the upper brackets to the tunnel casing, which are part of the load-bearing structure, were covered with passive fire protection – intumescent steel coating Nullifire SC902. This single-coat applied, quick-curing coating is based on a patented hybrid technology, thanks to which it combines outstanding application and performance properties with low volatile organic compounds (VOC).

Nullifire SC902 provides fire protection for steel elements for up to 120 minutes. In terms of VOC content, it meets the stringent requirements of the AgBB.

Nullifire SC902 intumescent steel coating offers many application possibilities. The greatest benefits of this product include fast curing and the ability to make all the required layer thicknesses in a single coat. In addition, this material is also weather resistant within one hour, can be applied in wet environments and cures at temperatures below 0oC.

The innovation of the Nullifire SC902 hybrid intumescent coating is that it allows one to obtain a thickness of up to 6 mm in single coat application, ensuring effective fire protection of steel elements up to 120 minutes after just 24 hours. For comparison, traditional coatings achieve full fire resistance after 7 days. I am glad that the advanced Nullifire technology, used in the largest investments in the world, including at the airport in Galeão International Airport in Rio de Janeiro, in the largest shopping centre in Scandinavia – Mall of Tripla in Helsinki, or skyscrapers forming the panorama of central London, such as Shard or 30 St Mary Ax, has also been used in such a prestigious project as the tunnel under Świna,” – said Wojciech Olszak, Key Account Manager at tremco Illbruck, part of CPG Europe, producer and supplier of Nullifire passive fire protection products.

The distributor that supplied the Nullifire SC902 intumescent coating for the tunnel project in Świnoujście was ALFASEAL GROUP Sp. z o.o. from Piaseczno.


  • CPG Europe

    Flowcrete is a leading brand of specialist, high-quality seamless resin floors for industrial and decorative applications. The company offers world-class flooring solutions based on synthetic epoxy, polyurethane, methacrylic and vinyl resins. Flowcrete resin floors are suitable for all industries and sectors of the economy. The brand offers durable industrial floors, antimicrobial floors, waterproof and flexible parking solutions, colourful decorative floors, including terrazzo and stone carpets and chemically resistant coatings. The producer and supplier of Flowcrete resin floors is Tremco CPG Poland Sp. z o.o., part of CPG Europe. CPG Europe, a regional division of RPM International Inc., is an umbrella for multiple leading European construction product brands, including illbruck, Flowcrete, Nullifire, Tremco, Vandex and Dryvit. CPG Europe employs over 1400 people across the continent and manufactures high-performance building materials and technologies that meet the complex requirements of the modern construction industry. Building technologies and materials provided by CPG Europe meet a wide variety of different construction needs, from sealing, bonding and insulation, to flooring, passive fire protection, waterproofing and roofing solutions.