With a random-looking spatter of paint specks, a pair of cameras, and a whole lot of computer processing, engineer Mark Iadicola of the National Institute of Standards and Technology (NIST) has been helping the Federal Highway Administration (FHWA), in cooperation with the American Association of State Highway and Transportation Officials (AASHTO), to ensure the safety of hundreds of truss bridges across the United States.

Iadicola has been testing the use of a thoroughly modern version of an old technique—photographic measurement or “photogrammetry”—to watch the failure of a key bridge component in exquisite detail.

The impetus for the FHWA project was the disastrous collapse of the Interstate 35-W bridge in Minneapolis, Minnesota. On Aug. 1, 2007, in the middle of the evening rush hour, 1,000 feet of the bridge’s main deck truss collapsed, part of it falling 108 feet into the Mississippi River. Thirteen people died; 145 people were injured.

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