Designed for pedestrians and cyclists, the bridge is designed to significantly improve the internal connections of this rugged part of the city. The project started back in 2009 and initially provided for the construction of two bridges at once. Only a part of what was conceived was realized, but the most interesting part. The project, which is not easy from a technical point of view, cost the city budget 4.7 million euros.
The sleek Y-shaped structure connects the banks of the Christianshaun and Tragraun canals in the heart of the Danish capital. The shorter "leg" (about 20 m) is motionless, and the two "wings" can be raised - both together and separately - providing free movement of vessels along the canals. Indeed, it looks like a giant butterfly. And, judging by the number of yachts and boats moored in the neighborhood, she will have to “flap her wings” quite often.
The bridge flaps - each about 23 m long - are controlled by two hydraulic cylinders mounted on a central platform. A rather thin (about 50 cm) and wide (slightly less than 8 m) bridge deck is based on an orthogonal structure made of anisotropic plates. But the rigidity is given to them by special "ribs", inside which the farms are hidden. They also separate the pedestrian part and the bike paths. The decision to hide the supporting structures made it possible to additionally protect them from corrosion. The width of these "ribs" is only 40 cm, and the height ranges from 50 cm at the edges to 170 cm at the attachment point of the hydraulic drives. As a result, the unprecedented thin and light profile of the bridge does not violate the integrity of the urban landscape, further reinforcing the association with the fragile, ephemeral butterfly.
The fixed parts of the bridge, due to special elastic inserts and oil shock absorbers, gently "accept" the sash. Simple structures can be easily dismantled or replaced in case of a possible reconstruction of the embankment or the necessary expansion of the roadway.
