The widely used tag for this is [area:highway][1] with values identical to highway. This had been used fairly extensively in Poland and the Polish community map has an overlay showing such areas ([here][2] in the centre of Warszawa, light stippled areas are area:highway=footway, darker areas motor roads). The proposal page on the wiki has more information: [https://wiki.openstreetmap.org/wiki/Proposed_features/area:highway].[3] [https://wiki.openstreetmap.org/wiki/Proposed_features/area:highway][3]. [1]: https://wiki.openstreetmap.org/wiki/Key:area:highway [2]: http://osmapa.pl/w/area/?lat=52.22991&lon=21.02253&zoom=17&ol=NQq [3]: https://wiki.openstreetmap.org/wiki/Proposed_features/area:highway

The widely used tag for this is [area:highway][1] with values identical to highway. This had been used fairly extensively in Poland and the Polish community map has an overlay showing such areas ([here][2] in the centre of Warszawa, light stippled areas are area:highway=footway, darker areas motor roads). The proposal page on the wiki has more information: [https://wiki.openstreetmap.org/wiki/Proposed_features/area:highway].[3] [1]: https://wiki.openstreetmap.org/wiki/Key:area:highway [2]: http://osmapa.pl/w/area/?lat=52.22991&lon=21.02253&zoom=17&ol=NQq [3]: https://wiki.openstreetmap.org/wiki/Proposed_features/area:highway