Mandatory direction arrows

RM8

Where: On any road before an intersection
Purpose: To show that you may only proceed in the direction indicated by the arrow in your lane.
Action: Choose the correct lane in time to travel in the direction you want to go. • Make sure that other traffic is obeying the mandatory direction arrows in their lanes. • Check your blind spot before turning right to see that a vehicle in the lane next to you who is suppose to turn right (because of the mandatory right-turn arrow in his lane) is not carrying straight on.

Manual on Road Traffic Signs, page 51.