Bridges are made to transport vehicles, not to make it easy for inspectors to do their job. That’s why inspecting the undersides and support pillars of tall ones is no easy task, either requiring people looking for problems to perform feats of contortion or the structure to go without review.
But infrastructure left without scrutiny is infrastructure bound to fail. In the case of the reinforced concrete that makes bridges, the test is a fairly straightforward one.
Inspectors use a device that checks for unseen corrosion within the concrete. The tool is an electrode attached to a wheel that detects big differences in electric potential within the material. This is a sign that corrosion—either from deicing salt that eats away the steel inside or atmospheric carbon dioxide that seeps in and changes the concrete’s chemistry—has set in and needs to be monitored.
The question is just how to get to those hard-to-reach spots. Now engineers and roboticists at the Swiss Federal Institute of Technology in Zurich (ETH) have developed a solution.