[Talk-us] Trunk

Paul Johnson baloo at ursamundi.org
Sat Oct 14 00:54:48 UTC 2017

On Fri, Oct 13, 2017 at 6:49 PM, Kevin Kenny <kevin.b.kenny+osm at gmail.com>

> On Fri, Oct 13, 2017 at 7:30 PM, Greg Troxel <gdt at lexort.com> wrote:
> > I don't think "important connecting role in the long distance road
> > network" should have anything to do with it.   A regular US highway that
> > is not divided, grade-separated, mostly limited access is still a key
> > interconnecting road, and it's squarely "primary".  Most of US 20 is
> > like this, as I understand it, and all or almost all of the parts I've
> > driven on (MA, WY) are like that.
> You're saying basically the same thing I've been saying. But... people
> who do routing and make maps are asking for three things, and
> we separate them only incompletely.
> (1) How "important" is this road to the long distance road network?
> If you look at a small-scale map of the state of Maine, you'll virtually
> always see US 1, 1A 2, 201; Maine 6, 11, 16, 161, 205. Maine
> has only the one Interstate (95) plus a loop (295 from Portland to Augusta)
> and a spur (395 into Bangor).
> This is what guides the decision to render a road at a given scale.

No argument here; I consider trunks and motorways as a special case of

> (2) What are the road's physical characteristics (access control,
> grade separation, number of lanes, width of shoulders, presence
> or absence of traffic lights and stop signs)?
> This is what guides the symbology to use. While Maine 205 is
> an important road in its area, it is NOT rendered as a freeway,
> or even a trunk. It's at best a primary and may even be a secondary,
> and that's how is should be rendered even on a small scale
> map.

I generally consider state highways as secondary unless they're quite large
or hit trunk or motorway.

> (3) How fast does traffic ordinarily flow on the road?
> This is what (should) guide the routing decision; routing is
> ordinarily done to save the driver's time. It is of key importance
> to navigation systems, but doesn't ordinarily guide rendering.

We don't even need to tag for this, as it can be inferred from the GPX
database instead.
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