A route=road relation specifies that its members are a part of a road network and are used for motor vehicle traffic. This relation is mainly used for major routes which have a ref=*. A value for ref=* may be unique in a smaller area (such as a city), but not in a larger area (such as a country); adding roads to a relation allows to distinguish parts of roads that are related and to make roles between parts of roads explicit. Most urban streets and minor roads which are identified only by a name=* tag do not belong to a relation.
See the route relation wiki for applicable members.
Relations tagged route=road may have the following tags in addition to the ones described in Relations/Routes:
||ID-number transmitted in electronic traffic-messages that identifies this road. See TMC_Import_Germany and TMC:LocationCode=* for TMC-locations.
Possible tagging mistakes