A method and system are disclosed for assisting the driver of a motor vehicle while driving through an intersection or road junction where at least three roads converge in a transition area. A future motion of an own or ego vehicle is estimated, and a future motion of a second vehicle is estimated. The probability of a collision between the own vehicle and the second vehicle is estimated based on the respective future motions. A search for a roadway marking arranged in the transition area is executed. If a roadway marking is found, the future motion of at least one of the own vehicle and second vehicle is estimated based on the detected roadway marking. A risk-reducing manuever is executed when the estimated collision probability exceeds a limiting value.