Zaha Hadid Architects

Three cranked blocks of housing step over an abandoned railway viaduct to stitch a run-down stretch of waterfront on the Danube Canal back into the city fabric. The arches of the viaduct, designed by Otto Wagner contain shop and restaurant units.

No additional load can be put on the viaduct so the new five storey concrete buildings have their own piled foundations. All new walls and soffits are clad with a cream insulated render the same colour as the stone quoins and the brick of the viaduct arches.

In two places the slot between the new building and the viaduct is glazed over and linked to one of the commercial units. 70mm diameter steel tubes span between the two structures supporting the glass roof and ends. The outer layer of the overhead glazing is laminated security glass so as to resist impact from any objects falling from the viaduct above.

The glass walls join at acute angles so the joints are formed by extending one pane of the sealed double glazed unit beyond the other to make a neat junction. Sharp corners are protected with steel angle cover strips adhesive bonded to the glass.

Where the overhead glazing meets the new wall a secret gutter is concealed within the depth of the insulation. On the viaduct side the glazing frames are built into the existing brickwork so that the glass appears frameless.