Relation:dual_carriageway

This is a proposal for a Relation to group the opposite carriageways of a dual carriageway.

To avoid duplication, the name/ref of the street should continue to be placed on the Ways of the street or in the Relation for the collected ways of a street. This relationship is only intended as a hint to renderers that the adjacent ways are actually part of the same street/road so the name could be positioned between the carriageways rather than in both, or the road number rendered only once for adjacent pairs of ways and similar applications.

For the same reason, the intention is that you would have one relation per pair of approximately adjacent ways. The grouping into complete streets would be done using Collected Ways or Routes.

There should not be an assumption that adjacent ways of a dual carriageway share a common bridge structure when crossing a bridge. This may or may not be the case - dual carriageways often have separate bridges carrying each carriageway. The commonality of a bridge can be indicated with the Bridge relation.

Tags

Key	Value	Discussion
type	dual_carriageway

Members

Way or Node	Role	Occurrence	Discussion
	(blank)	exactly two	approximately adjacent opposite ways in a dual carriageway

see also

The member-roles of type=route -relations and type=route with route=road in particular.