Reading the Lines: White, Yellow, Continuous, Broken

Two properties tell you everything a painted line has to say: its colour and whether it is continuous or broken.

Colour tells you what the line separates.

• White separates traffic moving in the same direction — lane lines on a dual carriageway or any multi-lane road.
• Yellow separates traffic moving in opposite directions — the centre line of an ordinary two-way road.

That distinction carries real information at a glance. A yellow line means there is oncoming traffic on the other side of it; a white line means the traffic beyond it is travelling with you. In poor light, before you can judge anything else, the colour tells you what crossing that line would mean.

Continuity tells you whether you may cross it.

• Continuous — stay on your side. No lane change, no overtaking across it.
• Broken — you may cross when it is safe to do so.

Put together, four combinations:

One special case: the double yellow line. Used to divide a three-lane one-way road or street into equal parts, for traffic all moving in the same direction. Note this is a different job from the yellow centre line above — the colour here is doing division rather than marking a direction change, which is why the doubling matters as a signal that something else is meant.

And the rule that governs all of them, unchanged from the positioning lesson: keep left, move right only to overtake, return left when the overtake is complete. The markings tell you where that is permitted; they do not replace the judgement about whether it is safe.