Empa innovation in bridge construction: Excellent railroad bridge thanks to Swiss carbon ropes
The multi-award-winning Oder Bridge near Küstrin is supported by a network arch with pre-stressed carbon cables. These ultra-light yet extremely stable carbon fiber reinforced plastic (CFRP) tension members were largely developed, tested and assessed at Empa.
A gleaming white network arch with a span of 130 metres supports the new border bridge near Küstrin. 88 carbon hangers stabilize the filigree construction over the Oder. This is the first time in the world that such tension members made of carbon fiber reinforced plastic (CFRP) have been used in a railroad bridge - developed by the Empa spin-off Carbo-Link and tested and assessed at Empa. 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 received two awards for this pioneering construction - the British "Bridges International Award" and the German Bridge Construction Award.
Lightweight carbon instead of steel weighing tons
According to the jury of the German Bridge Construction Award, the Küstrin Oder Bridge is not only a masterpiece of engineering, but is also forward-looking in terms of economy and sustainability. The 88 carbon hangers significantly reduce the dead weight compared to conventional flat steel hangers. This is because CFRP offers high tensile strength and better fatigue resistance than steel - while at the same time being significantly lighter. This opens up new design freedom, as the airy, transparent appearance of the Oder bridge impressively demonstrates. The material savings also lower construction costs and reduce maintenance costs in the long term.
In total, the use of CFRP hangers saved around 500 tons of steel and 1,350 tons of reinforced concrete in the bridge's overall structure. A sustainability study by Urs Meier, CFRP pioneer and former member of the Empa Directorate, shows: The carbon variant saves around 20 percent of CO₂ emissions compared to a steel structure.
High demands on the railroad bridge
The railroad 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 the structure at speeds of up to 120 kilometers per hour - which required extensive testing and complex approval procedures.
According to Lorenz Haspel, the responsible project manager 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 ropes for the first time as highly stressed tension members in a network arch on the light rail bridge in Stuttgart," says Haspel.
Most of the fatigue tests for the Oder Bridge were carried out by a team from Empa's "Structural Engineering" department led by Robert Widmann and Dimitri Ott in Empa's construction hall - and confirmed the necessary fatigue strength of the new CFRP material. Giovanni Terrasi, head of Empa's "Mechanical Systems Engineering" department, also prepared the technical report for the now award-winning bridge together with Christian Affolter. "We have thus created the basis for a new generation of filigree network arch bridges with carbon hangers as load-bearing elements," Terrasi is convinced.
Source: Empa
