The RiverArch proposal is far from the first example of a hybrid bridge-skyscraper. The ancestors to this idea are the ancient and medieval bridges with houses and shops on them, like the old London Bridge, above. The engineering difference between the old, real examples and the modern, unbuilt ones is that the old ones were empirically-designed buildings on empirically-designed bridges. As long as everything worked, everyone was happy. (At least on this topic.) The modern proposals are for analytically-designed buildings on analytically-designed bridges, which is a more difficult goal.
The example that I have long known about was dreamed up by Raymond Hood (one of my favorite tall-building architects) and Hugh Ferris. Their proposal was for a suspension bridge with skyscraper towers and smaller tall buildings distributed along the deck. It was not a particularly complete design, which could mean that it was meant to be thought-provoking rather than real, or it could mean that Hood was dropping bait to see if anyone was interested in funding such a project. The renderings are beautiful – as is all of Ferris’s work – and partially disguise the fact that the proposed buildings were not very big. The bridge’s skyscraper towers look not much larger than the (unoccupied) towers of the George Washington Bridge. Even if the skyscraper bridge towers were half again as tall and twice as thick, they’re not exceptionally large compared to the tallest buildings being constructed around the same time. So this part of the design is not so far-fetched. I do wonder about the vibrations and air-quality issues that might come from living over a bridge deck.
The opposite idea – skyscrapers with bridges rather than bridges with skyscrapers – also has a long history and modern examples. I’ve discussed some low-rise versions, but our old office at 111 Broadway has a bridge over Thames Street to 115 Broadway, and Moses King predicted more of the same in 1908.
