<div><div dir="auto">Hello, </div><div dir="auto"><br></div><div dir="auto">I totally agree with you, the definition you provide, administrative-free, tends to the same osm map between countries.  </div><div dir="auto"><br></div><div dir="auto">djakk</div><br><div class="gmail_quote"><div>Le jeu. 15 févr. 2018 à 19:18, Fernando Trebien <<a href="mailto:fernando.trebien@gmail.com">fernando.trebien@gmail.com</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Landing on this discussion several months late. I've just heard of it<br>
by reading a wiki talk page [1].<br>
<br>
Since 13 February 2009, the wiki [2] criticises highway classification<br>
as problematic/unverifiable. This has also been subject to a lot of<br>
controversy (and edit wars) in my local community (Brazil), especially<br>
regarding the effect of (lack of) pavement.<br>
<br>
In trying to achieve greater consensus some years ago, I decided to<br>
seek opinions elsewhere and finally I arrived at this scheme [3] which<br>
I think is very useful, if not perfect yet. It can be easily<br>
summarised like this:<br>
- trunk: best routes between large/important cities<br>
- primary: best routes between cities and above<br>
- secondary: best routes between towns/suburbs and above<br>
- tertiary: best routes between villages/neighbourhoods and above<br>
- unclassified: best routes between other place=* and above<br>
<br>
For example, the best route between two villages would be at least<br>
tertiary. So would be the best route between a village and a town or a<br>
city. Parts of this route might have a higher class in case they are<br>
part of a route between more important places.<br>
<br>
It surely raises the problem of determining optimal routes. Maybe a<br>
sensible criterion would be average travel time without traffic<br>
congestion. A number of vehicles may be selected for this average -<br>
could be motorcycle+car+bus+truck, or simply car+truck.<br>
<br>
Early results in my area [4, in Portuguese] seem promising and have<br>
produced more consensus than any previous proposals. To me, this<br>
method seems to:<br>
- resist alternations in classification along the same road<br>
- work across borders (where classification discontinuities are<br>
expected because each country is using different classification<br>
criteria)<br>
- account for road network topology<br>
- work in countries with mostly precarious/unpaved roads or<br>
without/unknown official highway classes<br>
- work between settlements as well as within settlements<br>
<br>
Borderline cases are probably inescapable in any system that does not<br>
use solely criteria that are directly verifiable - from the ground, or<br>
from the law. Maybe, in certain developed countries, the system is so<br>
well organized that merely checking signs/laws is sufficient. That<br>
does not mean it is like that everywhere on the planet.<br>
<br>
OSM has so far received a lot of input from communities in developed<br>
countries (mostly Europe, North America and Australia) and hasn't<br>
given much attention to less developed/organized countries. What comes<br>
closest to this is what the HOT Team does, but the judgment of road<br>
classification one can do from satellite images in a foreign country<br>
is much more limited than the criteria that have been raised in this<br>
thread so far.<br>
<br>
I wouldn't endorse tags such as maxspeed:practical due to lack of<br>
verifiability (it should be obvious that different types of vehicles<br>
would achieve different practical speeds). It is better to use the<br>
legal speed in maxspeed=* and describe the practical reason for a<br>
lower speed using surface=*, smoothness=*, and, who knows, maybe the<br>
not yet approved hazard=* [5] (though that is intended for signed<br>
hazards, not subjective/opinionated hazards).<br>
<br>
For the sake of long-term sanity, I also wouldn't mix the purpose of<br>
one tag with the purpose of other tags. To describe the surface, there<br>
is surface=*, smoothness=* and tracktype=*. To describe access rights,<br>
there is access=*, foot=*, bicycle=*, motor_vehicle=*, etc. To<br>
describe legal speed, maxspeed=*. To describe curves, there's<br>
geometry.<br>
<br>
Purpose, perhaps, is the main issue. What is the purpose of highway<br>
classification? Is it to save us the work of adding extra tags? Is it<br>
to allow the renderer to produce a cleaner output at low zoom levels?<br>
Is it to allow routers to assume default speeds? Maybe to guide their<br>
routing heuristics? Is it to express some sort of importance? If so,<br>
by which perspective - urbanistic, traffic engineering, movement,<br>
commercial value, cultural/fame, historic, some combination of those?<br>
Should the purpose be the same in every country?<br>
<br>
It may be interesting to also discuss the classification adopted by<br>
other maps. I don't have a reference for Google (originally TeleAtlas)<br>
or Here.com (originally Navteq), but Waze publishes its per-country<br>
road classification criteria in its wiki. [6-16]<br>
<br>
[1] <a href="https://wiki.openstreetmap.org/wiki/Talk:Tag:highway%3Dtrunk#change_.22high_performance.22_to_.22high_importance.22" rel="noreferrer" target="_blank">https://wiki.openstreetmap.org/wiki/Talk:Tag:highway%3Dtrunk#change_.22high_performance.22_to_.22high_importance.22</a><br>
[2] <a href="https://wiki.openstreetmap.org/wiki/Verifiability#Problematic_tags" rel="noreferrer" target="_blank">https://wiki.openstreetmap.org/wiki/Verifiability#Problematic_tags</a><br>
[3] <a href="https://wiki.openstreetmap.org/wiki/User:Ftrebien/Drafts/Generic_highway_classification_principles#Schematic_diagram_and_general_comments" rel="noreferrer" target="_blank">https://wiki.openstreetmap.org/wiki/User:Ftrebien/Drafts/Generic_highway_classification_principles#Schematic_diagram_and_general_comments</a><br>
[4] <a href="https://forum.openstreetmap.org/viewtopic.php?pid=674296#p674296" rel="noreferrer" target="_blank">https://forum.openstreetmap.org/viewtopic.php?pid=674296#p674296</a><br>
[5] <a href="https://wiki.openstreetmap.org/wiki/Proposed_features/hazard" rel="noreferrer" target="_blank">https://wiki.openstreetmap.org/wiki/Proposed_features/hazard</a><br>
[6] <a href="https://wazeopedia.waze.com/wiki/USA/Road_types" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/USA/Road_types</a><br>
[7] <a href="https://wazeopedia.waze.com/wiki/UnitedKingdom/Roads#Road_types" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/UnitedKingdom/Roads#Road_types</a><br>
[8] <a href="https://wazeopedia.waze.com/wiki/Canada/Main_Page#Road_Types" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Canada/Main_Page#Road_Types</a><br>
[9] <a href="https://wazeopedia.waze.com/wiki/Commons/Road_Types/India" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Commons/Road_Types/India</a><br>
[10] <a href="https://wazeopedia.waze.com/wiki/Brazil/Como_categorizar_e_nomear_vias" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Brazil/Como_categorizar_e_nomear_vias</a><br>
[11] <a href="https://wazeopedia.waze.com/wiki/Germany/Kartenlegende_(Deutschland)" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Germany/Kartenlegende_(Deutschland)</a><br>
[12] <a href="https://wazeopedia.waze.com/wiki/France/Classification_France" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/France/Classification_France</a><br>
[13] <a href="https://wazeopedia.waze.com/wiki/Italy/Tipologia_delle_strade" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Italy/Tipologia_delle_strade</a><br>
[14] <a href="https://wazeopedia.waze.com/wiki/Indonesia/Panduan_Tipe_Jalan" rel="noreferrer" target="_blank">https://wazeopedia.waze.com/wiki/Indonesia/Panduan_Tipe_Jalan</a><br>
[15] <a href="https://wiki.waze.com/wiki/%E9%81%93%E8%B7%AF%E7%B1%BB%E5%9E%8B" rel="noreferrer" target="_blank">https://wiki.waze.com/wiki/%E9%81%93%E8%B7%AF%E7%B1%BB%E5%9E%8B</a><br>
[16] <a href="https://wiki.waze.com/wiki/%E3%80%8C%E9%81%93%E8%B7%AF%E7%A8%AE%E5%88%A5%E3%80%8D" rel="noreferrer" target="_blank">https://wiki.waze.com/wiki/%E3%80%8C%E9%81%93%E8%B7%AF%E7%A8%AE%E5%88%A5%E3%80%8D</a><br>
<br>
--<br>
Fernando Trebien<br>
+55 (51) 99962-5409<br>
<br>
"Nullius in verba."<br>
<br>
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</blockquote></div></div>