Average speed check sign: what it means
The average speed check sign means two or more cameras measure your average speed between two points. Keeping to the limit the whole way is the only way to stay within it.
What does the average speed check sign mean?
Know your traffic signs describes it as a length of road where two cameras are used to measure the average speed of a vehicle between two points. It does not change the speed limit: the limit is shown on the normal speed limit signs.
Quick quiz
What does the sign at the top of this page mean?
- Cameras measure your average speed here.
- A speed camera is near, on a 30 mph road.
- The national limit for the road and vehicle applies.
Show answer
A. Cameras measure your average speed here. Two cameras measure the average speed of a vehicle between two points (Know your traffic signs). Source: Know your traffic signs: speed limit signs, GOV.UK; The Highway Code, rule 124, GOV.UK; Traffic sign images, Department for Transport, GOV.UK
Where will you see it?
On motorways, dual carriageways and other main roads, and often through road works.
What should you do?
Find the speed limit for the stretch and keep to it the whole way. Look out for repeater signs, because the limit through road works can be lower than usual.
What do people get wrong?
Braking at each camera and speeding up in between. The cameras measure your average speed over the whole stretch, so short bursts above the limit still count.
Common questions
Does an average speed check sign mean a lower speed limit?
No. It only warns that your average speed is measured. The limit is shown on the speed limit signs.
Is it only used at road works?
No. Average speed checks are used on ordinary roads too.
Compare with
Speed camera signA speed camera is near, on a 30 mph road.
National speed limit signThe national limit for the road and vehicle applies.
Want to test someone else? Play a road-sign quiz with friends and family.
Sources
Checked on 3 November 2026 against Know your traffic signs (speed limit signs) and The Highway Code rule 124.
- Know your traffic signs: speed limit signs, GOV.UK
- The Highway Code, rule 124, GOV.UK
- Traffic sign images, Department for Transport, GOV.UK
Contains public sector information licensed under the Open Government Licence v3.0. Traffic sign images are Crown copyright, from the Department for Transport. Sources and image credits.