Which line is used to mark the outer edge of the road?

A solid white line is used to mark the outer edge of the road. This line indicates the boundary between the roadway and the shoulder, helping to ensure that drivers stay within the designated travel area. Solid white lines are also used to indicate that lane changes should be avoided, particularly in areas where there may be increased hazards or a lack of shoulder space. Unlike dashed lines, which indicate that lane changes are permissible, or yellow lines, which are primarily used to separate traffic traveling in opposite directions, the solid white line serves a specific purpose in maintaining lane discipline and vehicle safety on the road.