From Dornbirn, a commercial and industrial town in Vorarlberg, a narrow road leads along the river Dornbirner Ache high upwards to a mountain valley. The river’s power became the central source of energy for numerous manufacturers and factories in Dornbirn back in the 18th century, and the prosperity that emerged on the river banks was based on it. This energy had already flooded the narrow valley before, and the river formed the rocks and steep slopes in a picturesque narrow passage, Ebniter Schlucht. The drive uphill on this narrow curving road, through tunnels and over bridges, lasts for approximately fifteen minutes, and then the valley opens up into a basin and ends high up in an old, former Walser settlement. Today, there is a tourist village here, a few houses, and yet also one little church.
Where this road crosses to the other bank for the last time, there is Schanerloch Bridge. The previous bridge became rundown after seventy years and it was decided to tear it down and replace it.
The power and massiveness of the landscape represented an important starting point for Bernhard and Stefan Marte. Careful observation of the location and a decision to take over the principle of an arch from the former bridge led to the design idea. The form was concretized in the process of working on a large-scale model and through conversations with the structural designer Josef Galehr from Feldkirch. The bridge should connect two massive rocks, should lean against them and be anchored like a bolt. At the same time, they wanted to react to the flow of the road and its somewhat curved position in relation to the narrow passage.
Eventually, a new interpretation of a massive arch bridge emerged which interprets the flow of the road and valley by its form. Coming from the valley, the road pushes through a rocky tunnel and then immediately bends to the right and goes right over the bridge and river. The bridge spans 21 m and as a consequence of the non-alignment of the two lateral wing arches, the bottom part of the bridge bends from one bank to the other at an angle of approximately 50°. The geometry of the slab thus created is realized in a surprisingly simple way by means of flexible shuttering panels on densely set beams that successively change direction. A high degree of bracing was obtained by this double bending and this concrete sculpture is logically stretched between the rocks in the direction of the flow of the road. If we observe the bridge’s cross section, we notice an elegant downwards narrowing, which accentuates the theme of anchoring and spanning between the rocks in a subtle way.
The bridge’s lively plastic corpus remains hidden to a motorized user in a discrete way, revealing its elegance only to a curious journeyman who approaches it from the side on foot or from the direction of the riverbed. Its unimposing beauty relies on the two fine arch arrows which overlap and seem to emerge from the landscape and then disappear back into it. The aesthetic impression lives on the antagonism of rough, porous rock and finely structured, almost smooth raw concrete. Its colour, which reminds one of stone, changes depending on the angle of the light from shiny white to the shadowy greyness of the patina which the concrete has taken on in time.
The total width of the bridge is 5 to 6 m, and the minimal width of the driveway between the concrete enclosures is 4.20 m. The enclosures are only 75 cm high; therefore the view of the surrounding landscape is unobstructed. The reinforced concrete arch is very slim and, with an anticipated load-bearing capacity of 40 t, is only around 45 cm thick at its thinnest point. The bridge’s foundations on load-bearing rocks on both sides facilitated dimensioning. The road slab is made of very rigid concrete and was joined to the bridge structure by means of poured bitumen.
The bridge that leads to Ebnit is not the first bridge project by architects Marte.Marte. Back in 1999, they executed a bridge widening, made of Cortene steel. In 2006, they won the competition for a pedestrian bridge made of reinforced concrete in Feldkirch, but the project failed due to local political resistance. This makes even more significant the fact that Schanerloch Bridge, finished in 2005, won the award for investor in Vorarlberg in 2010. On this occasion, one member of the jury made efforts to give an opportunity to the architects to renovate two more bridges. His desire has already been fulfilled. They have already been commissioned with the construction of at least one other bridge by the town of Dornbirn. What will this one look like? ‘An arch bridge, but with variations in comparison to the first one,’ say the architects.