Dual carriageways in the theory test: lanes, overtaking, speed limits and the end sign
Updated •5 min read
On a two-lane dual carriageway you should stay in the left-hand lane, using the right-hand lane for overtaking or turning right. The national speed limit for cars is 70 mph unless signs show otherwise (rule 137).
This page covers lane use, overtaking, crossing the central reservation, the speed limit table and the "dual carriageway ends" warning sign. Every rule is from the Highway Code on gov.uk.
What a dual carriageway is
The Highway Code says a dual carriageway is a road which has a central reservation to separate the carriageways. Amber studs mark the central reservation of a dual carriageway or motorway (rule 132).
Lane use (rules 137 and 138)
| Road | What the Highway Code says |
|---|---|
| Two lanes | Stay in the left-hand lane. Use the right-hand lane for overtaking or turning right. After overtaking, move back left when it is safe. |
| Three or more lanes | You may use the middle lanes or the right-hand lane to overtake. Return to the middle lanes, then the left-hand lane, when it is safe. |
Climbing and crawler lanes are covered by rule 139, and our road markings guide explains how they are marked. Rules for overtaking and being overtaken are in our overtaking guide, and lane closures at works are in our roadworks guide.
Speed limits for cars (rule 124)
The speed limit table in rule 124 gives these figures for cars and motorcycles, including car-derived vans up to 2 tonnes maximum laden weight.
| Road | Limit |
|---|---|
| Built-up areas (England and Scotland) | 30 mph (48 km/h) |
| Single carriageways | 60 mph (96 km/h) |
| Dual carriageways | 70 mph (112 km/h) |
| Motorways | 70 mph (112 km/h) |
The same table gives 60 mph on dual carriageways for cars towing caravans or trailers. Rule 124 also says you must not exceed the limit for the road and for your vehicle (gov.uk: rules 103 to 158).
Crossing or turning right across the central reservation (rule 173)
Rule 173 tells you to assess whether the central reservation is deep enough to protect the full length of your vehicle.
- Deep enough: 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.
- Too shallow: wait until you can cross both carriageways in one go.
The rule is in the Highway Code section on using the road.
The "dual carriageway ends" sign
"Dual carriageway ends" appears in the Highway Code's list of warning signs, which are mostly triangular (gov.uk: traffic signs). The name says the dual carriageway is about to end, so expect the road ahead to change.
When you see it, slow down and look ahead for how the lanes change. Take extra care before overtaking, because the layout ahead is about to change. Our road signs guide explains how the signs are grouped by shape and colour.
Other points to remember
- Hazard warning lights: rule 116 says not to use them while driving unless you are on a motorway or unrestricted dual carriageway and need to warn drivers behind of a hazard ahead.
- Fog: rule 235 says to be able to pull up well within the distance you can see, especially on dual carriageways, as vehicles travel faster.
Practise the rules
The free practice questions let you try these rules in question form, and the test centres page lists centres by city if you are booking.
Check what you remember
Try the free theorytest.ai diagnostic to see whether dual carriageways are a weak area. theorytest.ai is independent and is not affiliated with the DVSA. Gov.uk does not publish test questions, so we cannot say how many are about dual carriageways.
Frequently asked questions
Which lane should you use on a dual carriageway?
On a two-lane dual carriageway, stay in the left-hand lane. Use the right-hand lane for overtaking or turning right (rule 137).
What does the dual carriageway ends sign mean?
The dual carriageway is about to end. It is a warning sign, so slow down and watch how the road ahead changes.
What is the speed limit for a car on a dual carriageway?
70 mph (112 km/h), or 60 mph if towing a caravan or trailer, unless signs show otherwise (rule 124).
How do you cross a dual carriageway?
If the central reservation is deep enough for your whole vehicle, cross in two stages. Otherwise wait to cross both carriageways in one go (rule 173).
Can you overtake in the middle lane on a three-lane dual carriageway?
Yes. You may use the middle lanes or the right-hand lane, then return to the left-hand lane when it is safe (rule 138).