Components that cause corrosion are present: the electrical current in the light, the saltwater splash off trucks and clips clamped tightly to the fixture’s painted surface. “Whenever there is a bare spot, corrosion gets intense,” he says. “The powder-painted surface looks fine, but the clips could be scraping the paint,” he says. “If you’re counting on paint to be a barrier between two dissimilar metals touching each other, that could lead to corrosion,” he says.

The fallen light fixture was near the entryway of the tunnel, indicating the problem is not widespread. MassDOT likely will change its lighting specifications, he adds.