Samenvatting
Studies of incidents were used to evaluate the effectiveness of preventive measures installed on freeways and expressways as a result of previous research. Incident studies were also used to determine relative susceptibility of various off-ramp types to wrong-way movements. In addition, 1968 wrong-way drivers were interviewed. Movie camera surveillance of off-ramps was used to determine ''base'' wrong-way movement rates for particular ramp types. Relationships between wrong-way accidents and the factors of driver age and sobriety were also examined.