[Tagging] Classifying roads from Trunk to Tertiary and Unclassified
pla16021 at gmail.com
Tue Aug 13 11:33:08 UTC 2019
On Tue, 13 Aug 2019 at 04:23, Joseph Eisenberg <joseph.eisenberg at gmail.com>
> Rather than using highway=trunk to define a autovia, motorroad or
> expressway with a certain maxspeed=, lanes=, or surface quality, I
> believe it is better to either 1) follow the national classification
> system, when this is logical and internally consistent,
Hard agree. Even though it's starting to look like I live in the only
in the world with a national classification system that is logical and
internally consistent (and even we have a few rare exceptional cases). :)
> or 2) use network relationships and to assign a classification for a
complete road route between towns. Changing the classification from trunk
to primary to trunk again, in the middle of a rural area, breaks the
I don't really agree on this. It is possible for two trunks to be linked
by a primary.
In some cases it's mostly trunk from A to B with a bit of primary in the
In some cases two trunk routes, one from A to B and the other from C to D
have a primary linking them, and you'd use that primary to get from A to D.
And then there are cases where a section of a trunk road has been upgraded
to, or replaced by, a motorway.
UK map readers cope with these being rendered somewhat differently.
able to take secondary routes into account. These things are coloured
minor through routes and non-through routes are not. You look for the
linking A to B and try to figure out which is going to be best.
Where it goes wrong is people deciding that a trunk, primary, or even
through a town, city or village should be tagged as residential.
Certainly mappers should also tag maxspeed=, lanes=, surface=, and
> should map divided highways as 2 separate ways, and grade-separated
> intersections with bridge= and tunnel= + layer= so that routers will
> recognize faster routes.
Yep. But I don't see those as a way of allowing one to tag primaries as
They're a way of allowing routers to recognize that one particular primary
characteristics that are as good (or even better) than one particular trunk
either would be feasible alternative routes.
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