It is to separate traffic flowing in opposite directions
Areas of ‘hatched markings’ such as these are to separate traffic streams which could be a danger to each other. They are often seen on bends or where the road becomes narrow. If the area is bordered by a solid white line, you must not enter it except in an emergency.
B It marks an area to be used by overtaking motorcyclists
C It is a temporary marking to warn of the roadworks
D It is separating the two sides of the dual carriageway