national speed limit on a single carriageway uk
Road speed limits in the United Kingdom The national speed limit is 70 mph (112 km/h) on motorways, 70 mph (112 km/h) on dual carriageways, 60 mph (96 km/h) on single carriageways and generally 30 mph (48 km/h) in areas with street lighting (restricted roads). These limits may be changed by road signs and apply to cars, motorcycles, car-derived vans up to 2 tonnes maximum laden weight (MLW), and to motorhomes or motor caravans not more than 3.05 tonnes maximum unladen weight. Other classes of vehicles are subject to lower limits on some roads.[1]
Driving in the United Kingdom Drivers on dual carriageways (which may or may not be motorways) are usually expected to use the left-most lane unless overtaking other vehicles on the road, unless signs or road markings indicate that the left-most lane(s) is only for traffic leaving at the next junction. Drivers who wish to overtake a slower vehicle are thus expected to move out from their lane (having used the indicator lights to warn other road-users of their intention to do so), pass the slower vehicle and return to the left-most lane. This enables faster traffic to overtake unhindered if it wishes to do so. On the UK's busiest roads, where there may be four or more lanes in each direction, there is often a situation where overtaking becomes continual as each successive lane moves at a slightly faster speed than that to its left.