[Talk-us] US Trunk road tagging

[Zeke Farwell]

Well said, Adam!  I am thinking along the same lines.

On Thu, May 6, 2021 at 12:45 AM Adam Franco <adamfranco at gmail.com> wrote:

> On Wed, May 5, 2021 at 5:05 PM Paul Johnson <baloo at ursamundi.org> wrote:
>
>> > 3. Trunks should be important roads that fill in gaps in the Interstate
>> system between two large cities. This can be 4 lane US highways, but it can
>> also be 2 lane US highways, 4 lane state highways, you get the idea. The
>> main idea is that the road is filling an important gap in the interstate
>> system.
>>
>> That's what we have highway=primary for.
>>
>
> Using highway=primary as the highest class for 2-lane roads fails because
> it loses the idea that there are very important long-distance connectors
> that should be visible at low-zoom maps but don't have the traffic demand
> to warrant the expense of adding bigger physical infrastructure. Compare
> Carto's z6 and z7 rendering of the UK
> <https://www.openstreetmap.org/#map=7/54.553/-2.626> and the US midwest
> <https://www.openstreetmap.org/#map=7/37.423/-94.713> and note the
> difference in connectivity. A lot of the smaller roads through the far
> reaches of Scotland, Wales, and even England are non-motorway 2-lane roads
> that are physically constructed like many of our US highways and state
> highways.
>
> As an example, the A828
> <https://www.openstreetmap.org/way/29551321#map=11/56.5406/-5.2782> from
> Oban to Glencoe Scotland is a small 2-lane coast-road without a shoulder
> <https://www.mapillary.com/app/?lat=56.53804316&lng=-5.30388315&z=17.402428472937416&pKey=dS7J0mziCXvRUlKQdI8heg&focus=photo>
> for much of its length. It is however, the only connector road between the
> regionally important towns and cities of the west coast of Scotland. I get
> that OSM is based on the British classification system directly so it can
> be hard to retrofit actual principals onto British mapping practice. That
> said, I think we can avoid many of our problems by using 'trunk' as "the
> most important non-motorway roads" and not jumping right to primary. By
> jumping right to primary we lose the ability to filter data at low zooms to
> show only the most important long-distance and regional connectors and end
> up with this low-zoom patchwork of motorway islands that is hard to make
> sense of.
>
> At this point I'm thinking of the
> highway=trunk,primary,secondary,tertiary,unclassified,residential values as
> simply funny labels for descending numerical values of
> connectivity-importance. I'm now on board with the position that only
> motorway implies any physical characteristics.
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