FHWA defines a roadway departure (RwD) crash as a crash which occurs after a vehicle crosses an edge line or a center line, or otherwise leaves the traveled way. Another term our partners often use is lane departure, which is synonymous with RwD, since both include head-on collisions when a vehicle enters an opposing lane of traffic. From 2016 to 2018 an average of 19,158 fatalities resulted from roadway departures, which is 51 percent of all traffic fatalities in the United States.