Careless, sadistic, or just bad drivers are more of a concern than any specific type of vehicle. I do find that professional drivers are generally safer to be around than average yayhoos. Was riding with some friends in the mountains after storms had brought down dirt and debris and dozens of dump trucks were working all day and these drivers were so cool and careful and even waved us around them on descents when they had to go slow. Of course we were buzzed by an idiot in a small car the same day.