The Big Dig in Boston. Bechtel's Pride and Joy that exploited the city for plenty money. It's open finally. Guess what? Problems. Oh, really? Tim Mahoney, a retired teacher from Arlington, sat behind the windshield of his sport utility vehicle, which was damaged by debris falling out of an overhead vent in the southbound lanes of the Central Artery tunnel yesterday. (Globe Photo / Zara Tzanev)