Updated: Aug 2
To keep it simple, a dual carriageway is a road that has a physical barrier separating traffic going in different directions.
A lot of people seem to think that a dual carriageway means a road that has 2 lanes but that is not correct. A road can have 2 or more lanes and still be a single carriageway. It turns into a dual carriageway when there is a physical barrier separating the traffic travelling in opposite directions.
The barrier can be a metal barrier, a grass verge or concrete verge. If there is just paint separating the opposing traffic then that it a single carriageway.
It's important to know the difference between a single carriageway and a dual carriageway because when it comes to national speed limits, if you get it wrong, you could end up going too fast or too slow if you confuse the two.
What is the national speed on a single carriageway?
On a single carriageway, if you see the national speed limit sign, it means that the speed limit on that road is 60MPH if you're driving a car or motorcycle. If you are towing a trailer or caravan, then the speed limit will be 10MPH less which is 50MPH.
What is the national speed on a dual carriageway?
On a dual carriageway, the national speed limit is 70MPH. It is the same as a motorway when it come to national speed limit. And like the single carriageway, if you are towing a car or a trailer, the national speed limit is 60MPH. (10MPH less than the national speed limit)
So if you are confused, just remember that if there is a physical barrier separating the traffic going in opposite directions, then that is a dual carriageway.
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