Debris fell from a bridge onto a vehicle, breaking its windshield, on Interstate 495 north at the Route 3A overpass in Chelmsford Tuesday afternoon, State Police said. A piece of rusted steel hit the car while it was traveling in the middle lane, said Mike Verseckes, spokesman for the Department of Transportation. No injuries were reported. Verseckes said bridge inspectors found additional pieces of steel that were susceptible to falling, and immediately removed the loose material. Crews then closed the left travel lane to remove additional material that also had signs of corrosion. All lanes were back open by late afternoon. Kristina Egan, director of the Transportation for Massachusetts coalition, said Tuesday’s incident should serve as a warning sign that the state needs to pay special attention to its bridges. She said half the state’s bridges are structurally deficient or functionally obsolete.