A dual carriageway is defined as 2 or more lanes in one direction with 2 or more lanes in the opposite direction, and this must be separated by a central reservation. A dual carriageway would also be clearly signposted as such when you approach the point at which the road splits into two lanes.
If you are crossing a dual carriageway or you are on the carriagway and need to turn right, ensure that your vehicle is short enough to fit on the central reservation without causing an obstruction on either carriagway.
If your vehicle is longer than the space available in the central reservation, do not cross until both carriageways are clear and you can perform the manoeuvre in one go.
If your vehicle safely fits on the central reservation, treat each carriageway as a seperate road and wait on the central reservation until it is safe to cross the second carriageway.
All content is believed to be correct at time of publication.