180 Elsässertor II, Office and Commercial Building

Typical materials from the railways are used in the design of the immediate environs to link this newly created urban space with the railway territory beyond it. Railway ballast is rolled into the asphalt. Plant beds are filled with the same ballast and enclosed within railway rails. The birches and false acacias planted in the ballast beds are typical first colonisers of disused railway lines. The recycled cast iron rails enclosing the individual beds form little gardens that call to mind the terrace that used to be adjacent to the tracks.

The Elsässertor is a five-storey construction laid out as a very elongated, compressed pentagon. The edifice adopts a sharp, wedge-like profile as it nears the Margarethenbrücke, representing, as it were, the bridgehead. With its open pincer shape, the narrow side facing the French station creates a courtyard space. At that point, the roof of the Elsässertor folds downwards, allowing the station’s prominent corner tower to remain the dominant vertical element. The inversions at the building’s extremities and the receding lower ground floor on the street side mark the three points of entry to the Elsässertor.

The glass shell of the building, its acute structural angles and the atriums within allow natural light to flood the interior and give the building its transparency. The façade comprises of two layers, the outer one consisting of one-storey-high panes of glass that form the skin. The outer layer acts both as sound insulation to the north by attenuating the noise of the street, and as a heat shield to the south.

The arrangement of the inner layer is determined by the demands of the load-bearing structure, the layout of the rooms and the thermal management (one-storey-high glazing to the north; gradated solid parapets to the south). The regular patterning of the outer layer, by contrast, is determined by the physical dimensions and design of the building. It acquires a blue tint on the elevation nearest the Margarethenbrücke, and a red tint on the narrow frontage facing the station building; this allusion to the French tricolour helps bolster the identity of the Elsässertor. The edifice looks like a shard of cut crystal due to the various angles of inclination of the glazed panels north and south. The slight mirroring effect of the glazing throws back a fragmented image of the building’s immediate urban environs and gives the building an oscillating appearance.

Herzog & de Meuron, 2006