The University of Western Ontario Accident Research Team investigates every fatal crash, and approximately one in every fifty personal injury crashes, within a defined geographic area of three counties. Over a seven year period, the team investigated 107 collisions (62 fatal / 45 personal injury) which occurred on median-divided highways. These crashes are representative of over 2300 collisions on the highways involving 81 fatalities and injury to over 3200 vehicle occupants. Vehicle loss of directional control prior to any impact occurred in 55 of the 62 fatal cases and in 36 of the 45 personal injury cases. In 36 fatal cases and 17 personal injury cases loss of control was initiated after a vehicle travelled from the roadway onto the gravel shoulder. Rollover collisions were the most frequent collision type investigated and comprised 25 fatal and 25 personal injury cases with unrestrained occupants making up 24 of the 29 rollover fatalities. Collisions with an oncoming vehicle after median-crossover resulted in 26 fatal cases. These crashes were usually frontal or side impacts characterized by extensive vehicle damage and massive intrusion into the occupant compartment. Severe head injury (AIS 5 or greater) predominated as the cause of death in all collision types.