A teenager had head injuries after being struck by a vehicle in Danvers Tuesday evening, police said. Lieutenant William Carleton said the 15-year-old victim was crossing Route 62 at approximately 5 p.m. when he was hit. The youth was taken to Beverly Hospital and was later taken by helicopter to a Boston hospital, police said. Carleton said the victim was struck near where the Danvers Rail Trail crosses Poplar Street, although it was not immediately clear if the victim was on the path’s crosswalk. No further details were available Tuesday night.