Continuity lines

WM2

Where: On any road.
Purpose: To warn you that there is a break (intersection or off ramp) in the continuing part of the roadway and to inform you that if you are in a lane that has a line on one side, that lane will soon turn off from the road which you are now travelling.
Action: Yield to any traffic that wants to change lanes. The continuity lines will soon change to a channelizing line or painted island, which will make it illegal to change direction. Check your blind spot to make sure there are no other vehicles that might cut in front of you.

Manual on Road Traffic Signs, page 53.