[OSM-talk] Global consistency of the map (trunk etc.)

[Philip Barnes]

On Fri, 2012-04-06 at 20:16 +0200, Jan Kučera wrote:
> Hi guys,
> 
> I guess we need to standardize some things accross the whole globe...
> 
> for instance the usage of trunk tag... somewhere (like UK) it is
> single-carriage and elsewhere dual-carriage, one lane vs. multiple
> lanes. current approach and rendering is terribly wrong... we need to
> add special rendering for dual carriage trunk roads i guess

An interesting issue, I had always accepted the way things are done in
the UK to be pretty standard. Had never really looked at areas outside
the UK with my mapping head on until I put a long route into
http://open.mapquest.com with avoid motorways and was somewhat surprised
that it also avoided truck roads, well mostly as the route without them
is impossible. 

In the UK the term trunk road is a real term indicating a primary A road
that is maintained by The Highways Agency out of central taxation,
motorways are funded the same way. Some, well a lot actually, primary A
roads are maintained by local authorities, but are part of the primary
network so are mapped on OSM as trunk roads.

OSM in terms of it colours and road tags does work for us.

Motorways, blue signs, appear as blue roads.

Primary/Trunk A roads, tagged as trunk have green signs, appear as green
on OSM, these can be anything from a 2 lane road through a village to
the A55 in North Wales with virtual motorway regulations. There may even
be some single track trunk roads left in Scotland, am not sure on that
one. 

Secondary A roads, tagged as Primary, have white signs, appear as red on
OSM. Usually 2 lane.

B roads, tagged as secondary, appear as brown/orange on OSM. Usually 2
lane.

C roads, tagged as tertiary, don't know where this word came from as it
causes lots of confusion. C roads are the most difficult to identify as
there is little to distinguish them from unclassified and they are
rarely numbered on signposts. I have seen maps showing them on some
council websites, however am not certain of the right to use this data.

Actually OSM does produce a map with the road colours that everyone in
the UK is used to. A trunk road being anything from a near motorway, to
something where only one vehicle can pass a building at once is normal
and accepted here.

Phil