Bold brass

Road and rail tunnels are not often associated with inspirational design but this tunnel portal building in Austria, defined by perforated Nordic Brass copper alloy from Aurubis, takes a particularly bold approach.

The 5.5km long Bosruck Tunnel passes through the Ennstal Alps, connecting Upper Austria with Styria. The original, two-way traffic tunnel has been renovated and a second, new tunnel built alongside. Now part of the A9 Pyhrn motorway, it is used by around 18,000 vehicles each day. This impressive engineering feat is announced by new portal structures at both ends of the tunnel.

The highly architectonic approach taken is unusual for projects of this kind, suggesting a new building typology celebrating transport infrastructure. A series of screens – made up of perforated Nordic Brass cassettes, profiled and arranged to reflect the verticality of the surroundings – partially conceal buildings and equipment essential to the tunnel’s operation and safety. The rhythms of the screens highlight the experience of travellers as they approach and drive straight through the building, via the dramatic ‘flying roof’ entrance and exit galleries, acting as transition spaces between inside and out.

Nordic Brass was chosen for its long-life and durability, including resistance to road salt, following trials simulating the exposure of the material over 30 years. Along with three other Aurubis copper or copper alloy clad projects, Bosruck Tunnel has been shortlisted for the 2017 European Copper in Architecture Awards: All four shortlisted projects will also be featured on the Aurubis stand at the 100% Design event in London Olympia, 20-23 September.

Nordic Brass – also available with a pre-weathered finish – is produced by Aurubis, part of the world’s leading integrated copper group and largest copper recycler. Other copper alloys include Nordic Bronze and the innovative Nordic Royal, an alloy of copper with aluminium and zinc, giving it a rich golden through-colour and making it very stable.

The Aurubis architectural range also includes Nordic Standard ‘mill finish’ and Nordic Brown pre-oxidised copper, offering lighter or darker shades of brown determined by the thickness of the oxide layer. Various Nordic Green, Nordic Blue and Nordic Turquoise factory-applied patinas have also been developed with properties and colours based on the same brochantite mineralogy found in natural patinas all over the world.

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