Competition win – U4 extension to Grasbrook and Veddel

Moldauhafen subway station at night.

The three sections of the U4 extension.

View from Grasbrook to the new U4 Elbbrücke with the Freihafenelbbrücken.

Viaduct with V-shaped supports and openings to allow in light.

Access to Modauhafen station above the water.

The planning consortium made up of schlaich bergermann partner – sbp se, the architects von Gerkan, Marg und Partner – gmp, and WTM Engineers won first prize in the competition for the extension of Hamburg’s U4 subway line from the Elbbrücken station through to Grasbrook. In the two-stage realization competition organized by Hamburger Hochbahn AG, the team came out on top against a total of seven internationally composed planning consortia.
The almost 1-km-long infrastructure extension consists of three sections: a subway bridge over the Norderelbe, a connecting viaduct, and a double-story bridge over the Moldauhafen harbor basin with the station suspended above the water. The design convinced the jury thanks to its clear, consistent, and contemporary structure. The three parts of it possess a consistent and coherent design theme, which – without appearing forced – leads to an excellent integration of the elevated railroad line into the cityscape. The structure begins with three light, transparent, and extremely slender network arches with innovative carbon hangers that ensure minimal restriction of the view of the historic Freihafenelbbrücke bridge. After crossing the Elbe, the arches make a sweeping transition to the viaduct with its eye-catching V-shaped supports. Above Moldauhafen, the rhythm of the V-shaped supports condenses into a truss and becomes a bridge whose lower level can be used by pedestrians and cyclists, while the upper level houses the Moldauhafen subway station. The frame structure of the station roof evolves logically from the V-strut pattern and bears a semi-transparent photovoltaic glass façade.
Overall, the U4 subway line’s leap across the Elbe marks a milestone for sustainable and user-friendly infrastructure in the growing metropolis of Hamburg.