The default speed limit for cars on a United Kingdom single carriageway is 60 mph, unless signs say otherwise.
This national limit applies to cars, motorcycles, car-derived vans, and other vehicles in the relevant category when no lower limit is posted. A single carriageway is a road where opposing traffic shares one carriageway, although it may have more than one lane in each direction.
The United Kingdom uses different national limits for different road types. For cars, the limit is generally 70 mph on motorways and dual carriageways, 60 mph on single carriageways, and 30 mph in built-up areas unless a sign specifies another limit. Larger or towing vehicles can have lower limits.
The national limit is not a target speed. Drivers must reduce speed for bends, weather, visibility, traffic, roadworks, and other hazards. Speed-limit signs override the default, and local authorities can introduce lower limits such as 20 mph in residential or school areas.