[Talk-us] Tagging a super-two highway (trunk or motorway?)

[Chris Lawrence]

On Wed, Jun 26, 2013 at 2:36 PM, Paul Johnson <baloo at ursamundi.org> wrote:
> That would mean most freeways including interstates in the west, with the
> exception of limited sections in the bay area, southwestern California,
> central Portland and urban Seattle wouldn't be motorways, as restricting
> pedestrians and bicycles is unusual in 34 states.

To clarify, I meant that most states have some practice that involves
specially marking freeways; for example, California uses the "Freeway
Entrance" sign, as I believe is also the case in Nevada, Washington,
and a few other states, while in many other states the restrictions
are spelled out on a sign at the beginning of controlled access and
on-ramps.  Of course, there are states that don't post these
restriction signs (like Mississippi), and there are states that allow
certain categories of vehicle on some or all freeways that are
forbidden on other states' freeways.  But as a guide for figuring out
if a stretch of road is a freeway (and thus in OSM tagging a
highway=motorway) knowing field signing practices for freeways is a
helpful indicator, along with the legal designation of the route (if
the state makes a legal distinction between partial and full control
of access, regardless of the terminology).

And this isn't tagging for the renderer.  It's tagging based on the
western hemisphere translation of the concept of a "motorway," which
includes the possibility of undivided routes with full access control.
 Tagging for the renderer would be tagging undivided freeways as
trunks because we want them to be visually distinct from divided
freeways tagged as motorways in Mapnik's default style.

TLDR version: if there are signs at each end saying the road is a
freeway, and we have it tagged as a primary rather than a motorway
(the super two freeway section of US 101 in Washington State is
apparently an example, based on what He Who Shall Not Be Named says in
another forum), that's a problem. We can haggle over more ambiguous
cases like (presumably) MD 60 - I've never driven it and haven't done
any research with the state authorities, so I have no particular
expertise there.


Chris