Hydro and an external team of renowned structural engineers, business experts and researchers have investigated the feasibility and cost of replacing conventional steel with aluminium as a construction material for long-suspension bridge girders.

“The study is very encouraging and could potentially be a game-changer for bridge building and the use of aluminium in new ways in the future. It focused on what could be the longest aluminium bridge in world: 1,720 meters, 1,250 meters of which would be aluminium, equivalent to 8,000 to 10,000 tonnes,” says Thomas B. Svendsen, Market Manager in Hydro Extruded Solutions.

With the Langenuen project in Norway, we are getting closer to see if it is feasible to meet all the relevant design criteria for the bridge girder with aluminium solutions, including global stability, local stability, fatigue, ultimate global stress levels, and deflections.

“Aluminum has several advantages. An aluminum bridge does not corrode because the oxide coating of aluminum protects against corrosion. Paint is therefore not needed. Aluminum in the bridge can contain up to 100% recycled material, so aluminum is both a climate-friendly and cost-reducing material choice,” says Daniel Tran, risk engineer at the Norwegian Public Roads Administration.

New aluminium frontiers

The proposed Langenuen bridge, part of one of the largest infrastructure projects in Norway, the new E39 Coastal Highway Route, aims to reduce travel by replacing ferries with bridges, among other things.

The “Langenuen suspension bridge – Aluminium bridge girder alternative” report demonstrated that it’s possible to save time and money on production, material and maintenance by switching from steel to aluminium. Moreover, the technology could potentially be used in other suspension bridge girders.

The report was created by the independent structural engineering consultancy Dr.techn. Olav Olsen, Hydro, leading EPC (engineering, procurement and construction) supplier Leirvik AS and the Norwegian University of Science and Technology (NTNU). DNV GL has also been involved as a third-party verification agency.

“We are excited to see the potential of using aluminium in new ways for structural applications. Moreover, the new version of Eurocode 9, the reference standard for the design of aluminium structures, will include additional provisions to be applied to the structural design of aluminium bridges. This is interesting because structural engineers will then be able to refer to a set of consolidated design rules useful to replace more and more conventional steel with aluminium in their projects,” says Guido Sabatini, Technical Manager for building and standards at European Aluminium, a trade association.

Taking the next step

“With the promising results from this Langenuen study, this could be the start of a new way of thinking about aluminium as a strong, durable material and as a material that could be used in large infrastructure projects,” says Trond Furu, Research Manager in the Hydro Corporate Technology Office (CTO).

Now the project team goes into a phase 2 to review the remaining technical questions and methods to deem whether the project could be a reality.

“We have a great collaboration between Hydro CTO and the business areas in Hydro, which is instrumental in a project like this. We believe that aluminium has a great opportunity to be used in a range of new application areas and effectively compete against steel and other materials in many more areas than today,” Furu says.