On a three-lane dual carriageway the right-hand lane can be used for

Explanation: You should normally use the left-hand lane on any dual carriageway unless you are overtaking or turning right. When overtaking on a dual carriageway, look for vehicles ahead that are turning right. They're likely to be slowing or stopped. You need to see them in good time so that you can take appropriate action.

Category: Rules of the Road

References: The Official DVSA Guide to Driving: Section 11, Highway Code: Rule 137-138