[Talk-us] Mapquest does (or did) use relations

Nathan Edgars II neroute2 at gmail.com
Mon Oct 25 04:17:29 BST 2010

On Sun, Oct 24, 2010 at 10:17 PM, Phil! Gold <phil_g at pobox.com> wrote:
> * Nathan Edgars II <neroute2 at gmail.com> [2010-10-24 21:12 -0400]:
>> http://lists.openstreetmap.org/pipermail/talk-us/2010-July/003672.html
> And http://lists.openstreetmap.org/pipermail/talk-us/2010-July/003660.html
>> The results are a bit different now, so they may have changed their
>> rendering rules. Or maybe it was we who broke it when the refs on
>> relations were recently mass-changed to remove prefixes (Mapquest
>> apparently only rendered them if they had prefixes).
> I assume you're referring to my changeset #6030384.  I don't think that
> broke anything with Mapnik's shield rendering.  I updated every route
> relation in Maryland, and Mapquest is still putting shields on them.  The
> main ones I can see without shields are shared routes: a section of I-695
> that's also I-83, and the stretch where I-70 is also US 40.

Most likely those are from the ref tags on the ways. I panned over to
Maryland and don't see any shields on the I-70/US 40 overlaps, only on
either side. (Similarly the easternmost I-68 shields are in far
western Maryland where US 40 and US 219 split.) Formerly there were US
40 shields on the actual overlap, which was and is tagged ref=I 70;US
40 on the ways.
> Plus, I just double-checked their rendering rules (from
> http://github.com/MapQuest/MapQuest-Mapnik-Style ) and the way they're
> pulling data for shield rendering will only get ways, not relations.
> (They're only getting records that have highway= tags of motorway, trunk,
> primary, or secondary, which, of course, route relations don't have at
> all.)  So yes, they choose shields based on the route prefixes, but that's
> only on the ways themselves.  They (still) don't use route relations.

I was sure when I posted the linked message that only relations could
explain the observations (such as US 40 shields on ref=I 70;US 40
ways). I'm not in the mood to go over it again and find examples that
still work, but it's possible that they added another layer or
something on top of the main Mapnik rendering rules.

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