A 56-year-old man died after he was struck by a car while crossing a busy Bronx highway, police said Thursday. Robert Thompson was crossing the Cross Bronx Expressway near Gleason Ave. in Unionport from the south side to the north side about 9:55 p.m. on Wednesday when a 2011 Acura MDX slammed into him in the right lane, cops said. The car’s driver’s side hit Thompson, who was thrown into the far left lane and hit his head on the pavement, cops said. EMS rushed Thompson to Jacobi Hospital, but he couldn’t be saved. It was not immediately clear what Thompson was doing crossing the heavily traveled highway. Thompson, police said, lives in Prince’s Bay, Staten Island, more than 40 miles from where he was hit. A 58-year-old man behind the wheel of the Acura MDX remained at the scene. No charges were immediately filed. His license plate has a handful of violations attached to it, but nothing very serious.