portal design gleinalmtunnel a9 pyhrn motorway

realisation competition
in 2012, asfinag launched an invited realisation competition for the redesign of the south and north portals of the gleinalm tunnel as part of the full expansion of the a9 motorway. the composition of the jury — consisting of architects, representatives of the contracting authority, the building culture officer of the styrian state building authority, and a member of asfinag’s design advisory board — reflected the client’s awareness at the time of recognising its infrastructural facilities as an architectural and cultural challenge.
the long construction period is explained by the fact that a new second tunnel tube was first built, followed by the complete refurbishment of the existing one, and that the construction of the entrance portals took place in several phases.

brief
the brief defined three main requirements: the provision of winter service operations allowing snowploughs to enter and exit the gallery, the prevention of air crossover between the tubes, and the optical adaptation of drivers’ eyes from daylight to artificial light and vice versa.

the gallery as a speed funnel
starting from the existing clearance profiles of the tunnel entrances and exits, walls and ceilings fold upwards and outwards in triangular segments, expanding the space funnel-like. the driver enters a built speed funnel, subconsciously encouraged to reduce speed and increase attention.
the widened profile at the entrance — the funnel edge — is visible from a distance, signalling caution and preparing drivers for the tunnel approach. the entrance appears optically larger due to the expansion and the bright underside. transitions between walls, partial walls, and the tunnel opening are fluid, avoiding hard edges.
the wing-like form of the galleries conveys a sense of lightness and elegance while keeping the existing portal structure clearly legible as a strong, heavy form from afar.

closed and open sides of the galleries
the closed inner walls of the two galleries connect to the existing tunnel entrance walls and then fold outward, meeting at the end of the galleries to form a continuous wall that extends beyond the gallery to prevent air crossover. structurally, this creates a fixed support for the gallery roofs.
the roof folds upward in triangular sections; the downward-folded triangular walls form the second linear support for the roof. the tips of these triangles rest on parapet-like wall elements that protect against snow drifts. the roof’s folded geometry enhances structural stiffness, while the overall construction remains clear and legible.
the openings in the outer gallery wall gradually decrease in size toward the tunnel, forming a daylight funnel that allows the driver’s eyes to adjust progressively from daylight to artificial light and back.

surface and material concept
the concrete inner surfaces of the tunnel entrance zones, as well as the tunnel interior itself, are coated with a light-coloured finish. this so-called safety colour — a pale eggshell tone — has become standard in austrian tunnel construction, as long-term experience has shown it reduces accident risk. to ensure a unified appearance between tunnel and portals, the same tone was used in the gallery areas. all exterior surfaces exposed to weather are also protected by this durable coating.
the slightly folded interior and exterior wall and ceiling surfaces were executed with smooth finishes to avoid dirt-prone edges or recesses, allowing for easy cleaning and maintenance.

ventilation towers
the ventilation towers, located approximately 70 metres from the portals, were constructed in exposed concrete without additional coating. starting from a base cross-section of 4.50 m x 4.50 m, the geometry transforms — maintaining the same area — into an opening of about 2.25 m x 9.00 m at the outlet. this form supports the directed air discharge and reinforces the legibility of their function.