[OSM-newbies] Trunk and primary roads in Britain
Andy Robinson (blackadder-lists)
ajrlists at googlemail.com
Tue Dec 30 09:37:48 GMT 2008
We've taken the view (general consensus over time) that if the road is
signed with green/yellow signage then we tag it as trunk and for all other A
roads with black/white signage we tag as primary. The logical reason for
this approach is that it's easy to see on the ground that there is a
difference in the signage and thus easy to apply two different tags. It's
not perfect but then trunk and primary actually don't mean anything in other
Hope this helps.
>From: newbies-bounces at openstreetmap.org [mailto:newbies-
>bounces at openstreetmap.org] On Behalf Of Mike Harris
>Sent: 30 December 2008 9:11 AM
>To: newbies at openstreetmap.org
>Subject: [OSM-newbies] Trunk and primary roads in Britain
>Advice please for a relative newbie.
>Until the mid-1990s, trunk roads in Britain were managed by a central
>government agency (in England, the Highways Agency) and other roads,
>including other primary roads, were managed by local authorities. All
>primary roads were numbered "Annnn" (n - up to 4 digits) - many maps
>(including the Ordnance Survey) further distinguished trunk roads by adding
>a descriptor thus "Annnn (T)". OSM largely, but not entirely, reflects this
>historical situation with the separate tags highway:trunk and
>highway:primary being differently rendered (e.g. green for trunk and red
>for primary in Osmarender).
>The comment for trunk roads on the map features main page of the OSM Wiki
>"Important roads that aren't motorways. Typically maintained by central,
>not local government. Need not necessarily be a divided highway. In the UK,
>all green signed A roads are, in OSM, classed as 'trunk'."
>and for primary roads:
>"Administrative classification in the UK, generally linking larger towns."
>Unfortunately, in the mid-1990s nearly all trunk roads in Britain were "de-
>trunked" and their maintenance transferred from central to local government
>(in England, for example, the Highways Agency). There are now very few
>trunk roads in the country - see map at
>http://www.highways.gov.uk/aboutus/6151.htm . This change is reflected in
>most recent mapping (including the OS - note how the "(T)" suffix has
>disappeared from almost all A roads that formerly had it) - except OSM!
>If we take the current legal situation at face value, we should logically
>change in OSM most of the roads tagged as "trunk" to "primary" - and this
>would best be done wholesale rather than piecemeal (if this is possible).
>The current comments on the map features page are now at best confusing and
>perhaps incorrect. All A roads are green signed (or will be as older white
>signs are replaced) but almost all are maintained by local government - so
>the comment on trunk roads is now self-contradictory. AFAIK there is no
>administrative classification for primary roads other than as "A" roads -
>so the comment on primary road also contradicts the comment on trunk roads.
>Being a logical sort of person and wanting OSM to be up-to-date, I am
>tempted to change the advice in the Wiki and to change "trunk" to "primary"
>as I come across them via my GPX traces - but I don't want to act
>May I recommend strongly that we bring OSM up-to-date with the current
>administrative situation in Great Britain and reclassify trunk roads as
>primary wherever they have been detrunked? Is there a generic way of doing
>this centrally? (I am nowadays "only" a mapper and no longer a coder).
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