dual carriageway 
noun British
A road with a dividing strip between the traffic in opposite directions and usually two or more lanes in each direction.The new road will be a six-lane dual carriageway with two-lane service roads on either side....
- The road will be a dual carriageway in parts and will include bus lanes and facilities for cyclists and pedestrians.
- Millions of pounds are spent on wider roads, motorways, dual carriageways and assorted other roads.