Satellites are exposing weak bridges in America and around the world

Satellites are giving scientists a powerful new way to watch over the world’s bridges. Using radar imaging, researchers can detect millimeter-scale movements that may signal early structural problems long before inspectors notice them. The study found many bridges—especially in North America—are aging and increasingly vulnerable, but satellite monitoring could sharply reduce the number classified as high-risk. The approach could be especially valuable in regions where traditional monitoring barely exists.