A method and system for editing map data by automatically splitting a road segment into a pair of road segments while maintaining the proper attributes and directionality for each road segment. A road segment that has two directions of travel is selected for splitting. A new road segment is instantiated to represent one of the directions of travel. A direction of travel is assigned to both of the road segments. Attributes that are common to both directions of travel are copied to the new road segment. Attributes that are only associated with the direction of travel of the new road segment are migrated to the new road segment.