[Talk-us] Update on potential highway classification reform

Wed May 19 01:12:27 UTC 2021

"Early in the email trail someone pointed out the the OSM carto issue with a trunk road disappearing when it changed to primary. I think that is a problem with OSM carto, a trunk and a primary should show up on the same level."

Right idea wrong problem. The issue of "trunks disappearing" is caused by Americans using a tag for a purpose it wasn't meant to be used for. Trunks are your most important non-motorway roads.

The tag makes no assumption of quality of roadway, so when suddenly you have Americans using the tag that way, you get the zoom level that's supposed to show the most important roads in a network instead showing an incomplete game of connect the dots.

\-------- Original Message --------
On May 18, 2021, 7:51 PM, brad < bradhaack at fastmail.com> wrote:
I think the fundamental problem is that we have too many tags for a functional classification scheme. If trunk isn't going to be a limited access highway then perhaps it's redundant. Another option is to remove unclassified. Since we probably won't remove a redundant tag with a history, the renderers need to sort out the overlap.

This is my take:
Looking at the roads for my state of Colorado (& recently traveled areas in UT, AZ, NM) I think the highways could be reasonable be tagged as:
US highways: Primary
State highways: Secondary
County Roads: Tertiary, Unclassified, or Residential
Forest Service & BLM roads: Unclassified or track, maybe a few tertiary.
Using this criteria, it seems to meet the OSM wiki spec of 'The most important roads', 'The next most important roads', etc. There may be exceptions, but nothing seemed obvious to me inspecting my current home area, or previous home areas, or places I've driven.
You could also classify as US highway:Trunk, CO highways:Primary. That would work, but then the lower classes are difficult to classify (too many choices). Perhaps then unclassified is redundant.
I noticed that the mapper who lit off this email chain, oregonian3, recently changed many roads in Colorado (in addition to the roads in northern CO that Mike T noticed) from primary to trunk. At least one of those was changed back to primary by another mapper.

Early in the email trail someone pointed out the the OSM carto issue with a trunk road disappearing when it changed to primary. I think that is a problem with OSM carto, a trunk and a primary should show up on the same level.

On 5/17/21 3:54 PM, Brian M. Sperlongano wrote:
Hi Folks,

I'd like to provide the community an update on the work that's been happening to improve the current state of US highway classifications. Following the recent talk-us threads, there were extensive debates in Slack, especially in the \#local-us-northeast channel, about how to better apply the highway classification values with international norms, especially the trunk classification, which seems to be the most challenging.

There was a strong consensus initially amongst New England mappers that the highway classifications should be used in a way that's consistent with the connectivity importance of various roads. There was also a general agreement that documenting state-specific highway classification criteria was important for preventing edit wars as well as documenting edge or unusual cases and the rationale behind them.

The outcome of those discussions was the following wiki page\[1\], which offers general guidelines that can be applied in state-specific ways to come up with criteria that mappers can follow. As part of these discussions, local mappers have been drafting state-specific pages that would implement these general guidelines. State-specific criteria have been drafted so far for: MA, MS, NH, RI, VT, TX, and WA.

In order to demonstrate what the new classification would look like on the map, the New England mappers have put together a temporary live demo\[2\] which shows what this new arrangement would look like at the motorway and trunk level. This demo is set up to show the proposed "new" highway classification alignment in \*four\* New England states only: VT, NH, MA, and RI. The rest of the country is shown with no change to highway classification. In addition, this demo map is rigged to show motorway/trunk at their normal zoom levels, but suppress highway=secondary until zoomed in close, in order to specifically examine the motorway/trunk network in better detail.

Links:

\[1\] [https://wiki.openstreetmap.org/wiki/United\_States/Highway\_classification][https_wiki.openstreetmap.org_wiki_United_States_Highway_classification]
\[2\] [http://74.97.52.189:6789/openstreetmap-carto/\#7/43.250/-70.756][http_74.97.52.189_6789_openstreetmap-carto_7_43.250_-70.756]

I offer this update as an invitation to further collaboration on how we might better map highway classifications in the US.

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[https_wiki.openstreetmap.org_wiki_United_States_Highway_classification]: https://wiki.openstreetmap.org/wiki/United_States/Highway_classification
[http_74.97.52.189_6789_openstreetmap-carto_7_43.250_-70.756]: http://74.97.52.189:6789/openstreetmap-carto/#7/43.250/-70.756
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