Left-edge

RM4.1

Where: On the left and right-hand edge of the road.
Purpose: To indicate where the left or right-edge of the road is.
Action: Avoid driving to the left of the left-edge line. You may, however drive here only; • whilst being overtaken by another vehicle, • if you can so without endangering yourself, other traffic, pedestrians or property, • during daytime and • if persons and vehicles on the road are clearly discernible at a distance of at least 150 metres. It is not compulsory to drive to the left of the line when you are being overtaken, keep in mind that you have very little space when doing so. If your vehicle breaks down, stop as far left from the line as possible and switch on your emergency lights. The right-edge line is usually found on one-way roads such as dual carriageways or freeways and may not be crossed.

Manual on Road Traffic Signs, page 50.