Motorway Speed Limits in the UK
The national speed limit on motorways is 70 mph for most vehicles, but several vehicle classes have lower maximums. Smart motorway sections can impose variable mandatory limits enforced by cameras.
Speed Limits by Vehicle Type
| Vehicle Type | Speed Limit | Notes |
|---|---|---|
| Cars & motorcycles | 70 mph | National speed limit applies |
| Car-derived vans (< 2 tonnes) | 70 mph | Same as cars on motorways |
| Vans (up to 3.5 tonnes) | 70 mph | Same as cars on motorways only |
| Towing caravan/trailer | 60 mph | Must not use outside lane on three-lane motorways |
| HGV (over 7.5 tonnes) | 60 mph | Must not use outside lane on three-lane motorways |
| Buses & coaches (> 12 m) | 60 mph | Smaller buses limited to 70 mph |
Smart Motorway Variable Speed Limits
Smart motorways use overhead gantry signs to display mandatory variable speed limits. These limits change in real time based on traffic volume, incidents, or roadworks and are legally enforceable. When a variable limit is active, it replaces the 70 mph default.
Variable limits are typically set between 40 mph and 60 mph and are enforced by HADECS3 cameras mounted on the gantries or on the verge. These cameras can monitor up to five lanes simultaneously and use a small flash that can be difficult to notice during the day.
If a gantry displays a red X above a lane, that lane is closed and must not be used. Driving in a closed lane is a traffic offence enforced by the cameras and carries a minimum fine of £100 and three penalty points.
There are three types of smart motorway: all-lane running (no hard shoulder), controlled motorway (hard shoulder retained but with variable speed limits), and dynamic hard shoulder (hard shoulder opened as a running lane during busy periods). Following the 2023 government review, National Highways has paused the rollout of new all-lane running schemes, though existing sections remain operational.
Motorway Speed Limits Explained
UK motorways are designated by the prefix M (for example, the M1, M25, M6). The standard national speed limit on motorways is 70 mph, which has been in force since 1965 when Barbara Castle, the then Transport Minister, set the limit following a series of high-speed accidents on newly opened motorway sections. Before 1965, motorways had no speed limit at all.
Despite periodic campaigns to raise or lower the motorway limit, 70 mph has remained unchanged for over sixty years. Speed enforcement on motorways is carried out primarily by fixed cameras (Gatso, Truvelo), average-speed cameras (SPECS), smart motorway cameras (HADECS3), and mobile camera vans or handheld speed guns operated by traffic police officers.
Motorway speed limits apply to all lanes, including the inside (nearside) lane and the hard shoulder when it is opened as a running lane on a smart motorway section. There is no separate limit for the outside (fast) lane, though vehicles restricted to 60 mph -- such as HGVs over 7.5 tonnes and cars towing caravans -- must not use the offside lane of a motorway with three or more lanes except in certain circumstances, such as when lanes are closed.
The typical enforcement threshold used by UK police forces follows the NPCC (formerly ACPO) guideline of the speed limit plus 10% plus 2 mph. On a 70 mph motorway, this means prosecution is unlikely below 79 mph. On a smart motorway section displaying 50 mph, the threshold would be around 57 mph. However, these thresholds are guidelines only and police forces have discretion to prosecute at any speed above the posted limit.
Temporary speed limits during roadworks are common on motorways and are normally enforced by average-speed cameras (SPECS). These limits are typically 50 mph through major roadworks but can be as low as 30 mph or 40 mph. Exceeding temporary limits carries the same penalties as exceeding permanent ones.
Key Facts
Standard Limit
70 mph
Cars, motorcycles & vans
Variable Limits
40-60 mph
Smart motorway gantries
Enforcement Camera
HADECS3
Smart motorway enforcement
Towing / HGV Limit
60 mph
Plus lane restrictions
Frequently Asked Questions
What is the speed limit on a UK motorway?
The national speed limit on motorways is 70 mph for cars, motorcycles, car-derived vans, and buses or coaches not exceeding 12 metres in length. Vehicles towing trailers, HGVs over 7.5 tonnes, and buses over 12 metres are limited to 60 mph.
What speed limit applies on smart motorways?
Smart motorways display variable mandatory speed limits on overhead gantries. These are legally enforceable and can range from 40 to 60 mph. When no variable limit is displayed, the national speed limit of 70 mph applies. Limits are enforced by HADECS3 cameras.
Is there a minimum speed on UK motorways?
There is no minimum speed limit on UK motorways. However, driving abnormally slowly can be considered dangerous driving or driving without reasonable consideration for other road users, which is an offence under the Road Traffic Act 1988.