You've probably seen this triangle before: Fast, Cheap, Good — Pick Two. Here's a new bridge-building technique from Austria that seems to allow the customer to get a bridge that's faster, cheaper, better than traditional bridges.
From Popular Mechanics:
The umbrella method is a completely new way to construct a static final bridge. This TU Wien team first worked on the idea in 2006, and it's been experimenting and fine tuning since then. Instead of traditional kinds of bridge building—i.e. putting up long-term scaffolding as rebar is laid and concrete is filled into structures—this mechanism is built like a "closed" umbrella and then unfolded into its final position. From there, its hollow girders are filled with concrete and the rest of the structural elements are completed.
"Erecting bridges using scaffolding usually takes months," designer Johann Kollegger said in a statement. "The elements for the balanced lowering method, on the other hand, can be set up in two to three days, and the lowering process takes around three hours." But this process, he says, is less invasive for bridges through protected or uneven terrain. The team's sample bridge over the Lafnitz River touches a nature preserve.