A gleaming white network arch with a span of 130 metres supports the new border bridge near Küstrin in Switzerland.
A total of 88 carbon hangers stabilise the filigree construction over the Oder river. These tension members made of carbon fibre reinforced polymers (CFRP) were used for the first time worldwide in a railway bridge – developed by Empa spin-off Carbo-Link and tested and evaluated at Empa.
The new cross-border bridge at Küstrin consists of a network arch with a span of 130 metres and 88 carbon hangers. Image: Deutsche Bahn AG/Volker Emersleben.
The innovative material not only enables a particularly material-efficient construction method, but also significantly reduces CO₂ emissions compared to a conventional steel structure. The bridge has received two awards for this groundbreaking design – the British Bridges International Award and the German Bridge Construction Prize.
Lightweight carbon instead of heavy steel
According to the jury of the German Bridge Construction Prize, the Küstrin Oder bridge is not only considered an engineering masterpiece but is also pioneering in terms of economy and sustainability.
The 88 carbon hangers significantly reduce the weight compared to conventional flat steel hangers. This is because CFRP offers higher tensile strength and better fatigue resistance than steel – while also being significantly lighter. This opens up new design freedoms, as the airy, transparent appearance of the Oder bridge impressively demonstrates. In addition, the material savings reduce construction costs and maintenance requirements in the long term.
Trains can cross the Oder bridge at speeds of up to 120 km/h making use of carbon hangers for the first time worldwide. Image: Deutsche Bahn AG/Oliver Lang.
Overall, the use of CFRP hangers saved about 500 tonnes of steel and 1,350 tonnes of reinforced concrete in the bridge's overall structure. A sustainability study by Urs Meier, CFRP pioneer and former member of Empa's Directorate, shows that the carbon version saves about 20% of CO₂ emissions compared to a steel structure.
High technical requirements for railway bridges
The railway bridge over the Oder is a double-track network arch bridge in composite construction, equipped with prestressed CFRP hangers. Although such carbon cables have already been used on another bridge, this is the first time they have been used worldwide for heavy rail freight traffic. Trains can now pass over the structure at speeds of up to 120km/h – which required extensive testing and complex approval procedures.
According to Lorenz Haspel, the project manager responsible at the engineering firm schlaich bergermann partner, this carbon bridge would not have been possible without Empa.
The innovative CFRP hangers come from the Empa spin-off Carbo-Link in Fehraltorf – founded by Andreas Winistörfer, CEO and former Empa doctoral student – and have now been used for the second time in a network arch bridge. “We used such carbon cables for the first time as highly stressed tension members in a network arch on the city railway bridge in Stuttgart,” said Haspel.
Hangers made of carbon fiber reinforced polymer tested at Empa provide strength and sustainability. Image: Empa.
The fatigue tests for the Oder bridge were largely carried out by a team from Empa's Structural Engineering lab led by Robert Widmann and Dimitri Ott in Empa's construction hall – confirming the necessary fatigue strength of the innovative CFRP material.
Giovanni Terrasi, head of Empa's Mechanical Systems Engineering lab, also worked with Christian Affolter to prepare the technical report for the now award-winning bridge. “We have thus laid the foundation for a new generation of filigree network arch bridges with carbon hangers as load-bearing elements,” said Terrasi.