[OSM-talk] Highway=trunk : harmonization between countries ?

Greg Troxel gdt at lexort.com
Thu Aug 24 00:09:29 UTC 2017

djakk djakk <djakk.djakk at gmail.com> writes:

> The thing is, I'm annoyed when there is a primary in the middle of a trunk
> road (example : https://www.openstreetmap.org/#map=12/44.3996/-70.9439)

I haven't been there, but the notion that the road is fundamentally
different in the primary section is totally sensible and likely to be

> whereas in the U.K. this does not exist ... tagging rules should be as
> generic as possible, should not they ?

In an alternate universe, where tags were developed from the ground up
by committee and vetted against each country's reality, before any
mapping was done, perhaps.  But that's not what OSM is, for better or
for worse.  There was a scheme that really made sense in the UK, and
it's been adapted.

In the US (are you in the US?), there isn't any formal notion of trunk.
There are US highways, which were agreed long ago to map to primary, and
there are Interstates, which were agreed to map to motorway.  This
mapping is arguably sensible.

My impreession is that in the UK, there were A/B/C/U, and then later M
were created, and I'm not sure when trunk happened.

In the US there were US and state highways, and then later I-.   We
don't have a naming system for trunk.   So therefore, we have adapted
high-grade physical to mean a better type of primary.  And basically
almost everybody is OK with this.

If we are going to have the consistency you want, the way would be to
downgrade the trunk sections to primary, because after all it's US 2,
not "Trunk 2".  In the UK, it would be the A2, and unquestionably

The real problem is not that trunk means what it does.  It's that
renderers and perhaps routers focus on the main highway tag, and make
results you don't like.  Perhaps you should make your own render, and
submit change proposals to the standard style.  A possibility might be
coloring roads by ref and hence legal designation, not highway tag, and
then to draw their width/weight based on physical characteristics.  If
that's useful, and I think it might be, maybe people will adopt it.

But changing the definition of trunk because you don't like the
rendering output is even worse than tagging for the renderer - it's
meta-tagging for the renderer :-)
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