Do not disturb: Species protection in bridge construction

When the salmon are moving through the river, the work in the water at the new city bridge in Drammen, Norway, comes to a standstill. Because species protection has priority.

Around 100,000 people live in the former working-class town of Drammen. It is about 30 minutes by car from Oslo. At the mouth of the Drammenselva. More than 40 species of fish live in this river. Among them are salmon. Now the town is getting a makeover. And PNC Norge, a subsidiary of the PORR Group, is playing a major role in shaping the project. It was commissioned to remove the old bridge on the Drammenselva and build a smart city bridge worth around EUR 85m and a new wharf in its place. “The bridge is one of the key features of Drammen’s landscape and very important for the character of the city. Here PORR is applying its huge expertise in bridge construction”, explains Karl-Heinz Strauss, CEO of PORR. A particular focus here? Species protection.

All-round renewal

The elegant white bridge will traverse the River Drammen from 2025. It will form a core part of the city’s axis between the main square and the railway station. The 180m-long steel bridge will be 19.4m wider than before and users will be able to cross it by car, bicycle or on foot. “The old bridge was built in 1936 and was only designed to last 50 years. So it is high time to replace it. Our bridge is built to last at least 100 years”, says Karl-Heinz Strauss. The new bridge construction is thereby the core element in the complete overhaul of Drammen. Among other things, the city centre will be upgraded, traffic will be diverted outwards, and the waterfront promenade and the railway station will be redesigned.

And so the new connection is created: Works will start with the removal of the existing bridge and breaking up the foundations in the water. Then, work on the new river foundations and supports will be carried out on two floating platforms, each measuring 20x20m. Then the steel parts will be installed and the project rounded off with a complete surface design. The parts for the steel-bridge will be transported by barge from PORR’s new steel construction production plant across the sea to Norway - transport by water is an effective and climate-friendly alternative to land transport.

During the construction of the Bybrua in Drammen, Norway, the passing salmon must not be disturbed. (c) PORR

All-round protection

One challenge is the many points of contact with the Norwegian state railway Bane NOR, which is renewing the tracks and pedestrian crossings in the immediate vicinity of the bridge. “For us, there is another challenge to this project - and that is the protection of native species”, says Karl-Heinz Strauss. “This is a particular issue in Norway and there are very strict requirements for construction companies. Between May and September, for example, we are not allowed to disturb the migrating salmon with any work in the water”. In addition to the salmon, the River Drammen is home to 42 different species of fish. “The bridge is not scheduled to open until August 2025 to give the salmon enough undisturbed time to spawn during the summer months”.

Facts and figures

  • Project type: Bridge construction/steel construction/demolition

  • Scope of services: New construction of the city bridge in Drammen and demolition of the existing bridge. The new bridge will be built on two foundations in the river and the support structure will be made of steel. Additional surface works and installation of a recreational quay.

  • Client: Municipality of Drammen

  • Contractor: PNC Norge AS

  • Contract period: May 2022 to April 2026, bridge set for completion in August 2025

  • Contract volume: NOK 859m (around EUR 85m)