Construction engineer John Tsikouras suspected that the salesmen were not telling him the whole story. The men from Newman Associates, a bolt distribution company, approached him in August 1999 and said they wanted his professional advice about a tunnel ceiling that was part of Boston's Big Dig. But Tsikouras said their questions seemed intended to get the Rhode Island engineer's approval rather than his expertise. Would it be safe to hang the concrete ceiling from 7.5-inch-long bolts? No, Tsikouras said. What if the bolts were 5 inches long instead? "I can ask my mother that one," he replied: Even less...