On a two-lane dual carriageway you should stay in the left-hand lane. Use the right-hand lane for overtaking or turning right. After overtaking, move back to the left-hand lane when it is safe to do so.
On a three-lane dual carriageway, you may use the middle lane or the right-hand lane to overtake but return to the middle and then the left-hand lane when it is safe.
Dual carriageways. When crossing or turning right, first assess whether the central reservation is deep enough to protect the full length of your vehicle.
- If it is, then you should treat each half of the carriageway as a separate road. Wait in the central reservation until there is a safe gap in the traffic on the second half of the road.
- If the central reservation is too shallow for the length of your vehicle, wait until you can cross both carriageways in one go.
Rule 173: Assess your vehicle’s length and do not obstruct traffic
If your vehicle breaks down, think first of all other road users and
- get your vehicle off the road if possible
- warn other traffic by using your hazard warning lights if your vehicle is causing an obstruction
- help other road users see you by wearing light-coloured or fluorescent clothing in daylight and reflective clothing at night or in poor visibility
- put a warning triangle on the road at least 45 metres (147 feet) behind your broken-down vehicle on the same side of the road, or use other permitted warning devices if you have them. Always take great care when placing or retrieving them, but never use them on motorways
- if possible, keep your sidelights on if it is dark or visibility is poor
- do not stand (or let anybody else stand) between your vehicle and oncoming traffic
- at night or in poor visibility do not stand where you will prevent other road users seeing your lights
The Highway Code © Crown copyright. Source: http://gov.uk/highway-code