Bridge Tower, framing and sky boxes
A recent forecast estimates that humankind will construct roughly the same volume of buildings within the next generation as that which currently exists today. A significant portion of this volume will be in the form of tall buildings in urban centers. If realized, not only will this volume require the use of massive amounts of material and energy resources, but the conventional strategy of tear-down and rebuild would result in an equally enormous level of waste.
Aggressive building campaigns are criticized as being heavy-handed and insensitive to the particulars of context. However, we shouldn’t lose sight of the sheer force of ambition exemplified by proposals such as Superstudio’s urban-scaled monuments (left). In fact, these visions informed a new generation of ambitious structures conceived decades later. It would appear that to some architects, the skyscraper should not merely be an expression of verticality. It must also create connections.
Bridge Towers
But what of the existing buildings that new skyscraper proposals typically replace? Is it possible to create connections within the existing fabric of the city, capitalizing on its embodied energy, resources, and infrastructure? Using the existing city as a foundation, an overlay of bridges, pathways, or lattice-like canopy might provide new space with minimal disturbance. These structures could straddle existing buildings delicately, and might even connect underground, thus creating an additional layer of sectional continuity within the city. Preliminary studies reveal a suspended lattice structure—like a tree canopy for the ‘trunks’ of existing structures.
Conventional tear down and rebuild vs. upgrade and connect
A simple, singular connection provides a good starting point. A “bridge tower” could enshroud and link two existing buildings, providing the same amount of volume as another tower. A series of carefully located city rooms or “sky boxes” could elevate multi-functional community spaces above the street, while providing points for geometric inflection in the new facade. A quick study by Arup reinforced the structural viability and development case for the proposal. The design should also have a lower environmental cost compared with an entirely new tower.
Bridge Tower viewed from mid-air
The proposal for an additive urban shroud acknowledges the existence of significant amounts of embodied energy within existing buildings, particularly tall office and housing towers designed to last many generations. As the facades of these towers become obsolete from an energy standpoint and require replacement, a new structural envelope may be overlaid onto the buildings. This solar-harvesting ETFE architectural shroud would not only provide superior cladding, but also connect disparate structures while providing the additional volume equivalent of another tower.
Bridge Tower SLS model
Linkages above and below ground would result in a kind of urban loop which could be highlighted by the placement of multiple city rooms. These rooms would serve as sky boxes, mixing chambers, and winter gardens that support new kinds of social activities not enabled in conventional tall structures.
Bridge Tower showing internal towers and scaffolding
Credits
Blaine Brownell: concept and design
Kelly Day: physical model, photo montage and plaza design
Brian Glover: structural and economic study
The Book
Read more about “Inescapable Mutuality” and the bridge tower proposal in this design brief, which is available in both print and electronic editions.
