A Massachusetts tractor-trailer driver who crashed on a Vermont highway during a snowstorm and then stepped out into traffic was struck and killed by another vehicle. Vermont State Police said Robert Trombley, 45, of Lee, Mass., was traveling on Interstate 93 in Fairlee Friday morning when his tractor-trailer slid and hit a guardrail. They said the tractor-trailer was stopped in the middle of the interstate, blocking both lanes. State Police said Trombley got out and was standing in the travel portion of the interstate when he was hit by an oncoming vehicle during whiteout conditions. Trombley was taken to Dartmouth Hitchcock Medical Center in Lebanon, N.H., where he was pronounced dead.