Key:highway_authority_ref
 highway_authority_ref
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| Description |
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Road reference for internal use by the highway authority. 
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| Group: highways |
| Used on these elements |
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| Requires |
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| Useful combination |
| See also |
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| Status: in use |
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The key highway_authority_ref=* indicates a road reference, similar to ref=*, but from a reference system that is primarily intended for internal use only by the highway authority/operator for administrative purposes.
Such references are generally not signed and not used for navigation. Consequently, tagging these references in OSM is primarily useful for data fusion with other data sources.
European use
Netherlands
Rijkswegen
In the Netherlands, highway_authority_ref=Rijksweg * is used to indicate Rijksweg-numbers. Only roads with operator=Rijkswaterstaat can (but need not) have a Rijksweg-number.
All roads with a Rijksweg-number also have either an A-number or an N-number. (The reverse is not true, e.g. N209.) The Rijksweg-number is never indicated on road signs. Only the A-number or N-number is communicated with the road user.
In most cases, the Rijksweg-number is implied by the A-number/N-number tagged as official_ref=* or ref=*, making explicit tagging of highway_authority_ref=Rijksweg * unnecessary. The exceptions to this rule are:
- either the Rijksweg-number differs from the A-number/N-number;
- or the A-number/N-number is outside the 1-100 range, which is the range of A-numbers/N-numbers officially reserved for Rijksweg-numbers.
In these exceptional cases, a Rijksweg-number must be tagged explicitly, if present. This includes (but is not limited to) all so-called planvervangende wegen, as they have a Rijksweg-number ≥100.
The currently used Rijksweg-numbers of road sections can be retrieved from the Nationaal Wegenbestand or the Actuele Wegenlijst.
Waterschapswegen Hollandse Delta
Roads with operator=Waterschap Hollandse Delta can have administrative Y-numbers (highway_authority_ref=Y*). These Y-numbers can be retrieved from WSHD Beheerregister Wegen.
Currently, these Y-numbers are not signed. In the past, the Y-numbers have in some cases been indicated on small roadside signs.
United Kingdom
In Great Britain, highway_authority_ref=C* is used to tag C-road numbers. These road numbers are rarely signed[1]. This is also applied to roads where there is a signed number but a different number is used for the road, however this is very rare.[2][3]