Maximum speed limits in Britain vary according to the type of road you are on and the class of vehicle you are driving. These speed limits are set out in the Highway Code and are shown in the table below. Where local speed limits apply, these are shown by signs at the point where the speed limit starts and by repeater signs throughout the length of the speed limit. In a local speed limit, drivers must not exceed the speed indicated by the signs, or the maximum speed for the class of vehicle, whichever is the lower.
 
For information on the legal requirements about speed limit signs, see our page on speed limit signing requirements.
 
Where signs do not show a local speed limit, drivers are expected to know what the speed limit is according to the type of road. In built-up areas — defined as roads where there are street lamps spaced not more than 200 yards (183 metres) apart — the speed limit is 30mph for all classes of vehicle, unless signs show that a local limit or a national speed limit applies. Thus the presence of street lamps, coupled with a lack of speed limit signs, should be taken to mean that the speed limit is 30mph, although there must still be signs at any point where a 30mph limit begins from any other speed limit (local or national). More details of the signing requirements for 30mph limits in built-up areas are shown on our speed limit signing requirements page.
 
Outside built-up areas, the national speed limit applies where there is no local limit. The point at which a local speed limit (or the 30mph limit in a built-up area) ends and the national speed limit begins is shown by the following sign:

This sign should also be displayed at intervals as a repeater sign along roads that have street lamps but where the national speed limit applies, instead of the 30mph limit that should otherwise be assumed. (This does not apply to motorways.)
 
The national speed limit differs according to the type of road, and it is here that some drivers can be confused. There are three types of road: single carriageway, dual carriageway, and motorway. The national speed limits that apply to them are shown in the table below.
 
While most drivers are clear about what a motorway is, some are confused about the definition of a dual carriageway. For a road to be classed as a dual carriageway, the two directions of traffic flow must be physically separated by a central reservation. A road where the two directions of flow are separated only by lines painted on the road surface is a single carriageway, regardless of the number of traffic lanes that may be available to the traffic in each direction. So a road with three or four lanes is still a single carriageway if there is no central reservation. The following diagrams should clarify this point:
 
Single carriageway with 2-lanes
 
Single carriageway with 3 lanes (e.g. two lanes uphill)
 
Single carriageway with 4 lanes
 
Dual carriageway with 2 lanes in each direction
 
The most important difference in the national speed limit is between single and dual carriageways. On a single carriageway road, cars and motorcycles are restricted to 60mph and heavy goods vehicles to 40mph. On dual carriageway roads, the respective speed limits are 70mph and 50mph. It appears that some speed camera partnerships may be deliberately targeting single carriageway roads for enforcement where they have three or four traffic lanes, knowing that some drivers wrongly believe they are on a dual carriageway and a higher speed limit applies. The following table shows the full range of national speed limits.
 
National Speed Limits (outside built-up areas)

Type of vehicle	Speed Limit (miles per hour)
	Single Carriageway	Dual Carriageway	Motorway
Cars, motorcycles, and car-derived vans up to 2 tonnes maximum laden weight
Cars (inc. car-derived vans and motorcycles) towing caravans or trailers
Buses, coaches and mini-buses (not exceeding 12 metres in length)
Goods vehicles not exceeding 7.5 tonnes maximum laden weight			*
Goods vehicles exceeding 7.5 tonnes maximum laden weight

* The speed limit is 60mph if the vehicle is articulated or towing a trailer.
 

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