[Tagging] Classifying roads from Trunk to Tertiary and Unclassified

Fernando Trebien fernando.trebien at gmail.com
Mon Aug 12 17:23:20 UTC 2019


The international confusion is maddening, but this generic guideline
has helped reach consensus in my area in Brazil:
https://wiki.openstreetmap.org/wiki/User:Ftrebien/Drafts/Generic_highway_classification_principles#Schematic_diagram_and_general_comments

Here's the result after a lot of discussion in the local community:
https://wiki.openstreetmap.org/wiki/WikiProject_Brazil/RS/Classifica%C3%A7%C3%A3o_das_rodovias_do_RS#Mapa_de_primary.2C_trunk_e_motorway_no_Rio_Grande_do_Sul

There are all sorts of opinions on this matter, but trying to define
classification rules based on physical characteristics or
administrative responsibility (municipality, state or national) always
led to unexpected situations here. I guess the UK is somewhat unique
in having an official classification system that matches the
topological organization of the road system.

On Sat, Aug 10, 2019 at 5:27 AM Joseph Eisenberg
<joseph.eisenberg at gmail.com> wrote:
>
> We recently discussed the confusion about unclassified vs residential
> recently, but a more significant issue is that different countries and
> regions have a wide variety of practices about assigning the major
> highway classes, especially trunk and primary.
>
> In some countries, including parts of Europe and parts of the USA,
> highway=trunk is reserved for "expressways" or "motorroads" with
> certain physical characteristics. However, in England where the tag
> originated, highway=trunk is used for the main, non-motorway highways
> in the country. As can be seen by glancing at the rendering of
> England, these highway=trunk connect just about every place=town in
> England: https://www.openstreetmap.org/#map=6/53.021/-1.033
>
> This means that highway=primary and highway=secondary is used for most
> other paved roads with one lane in each direction. Many place=villages
> in England are connected to a  highway=primary and the rest have a
> highway=secondary. And most hamlets are on a highway=tertiary which
> connects to larger villages or a town.
>
> This leaves highway=unclassified for very minor roads, often too
> narrow for 2 wide vehicles to pass each other, connecting isolated
> dwellings and farms. This is how they are like residential roads, in
> the English system.
>
> I would like to adapt this system to Indonesia, where the government
> has not yet classified most roads below the National level, but the
> "Jalan Nasional" class of major highways has already been decided to
> be mapped as highway=trunk.
>
> See https://wiki.openstreetmap.org/wiki/Indonesian_Tagging_Guidelines#Roads
> for an attempt.
>
> The idea is that one can determine the classification of highway based
> on what size of settlements it connects:
>
> trunk - connects cities to cities ("National Roads")
> primary - connects a town to a city or another town
> secondary - connects a village to a town/city or another village
> tertiary - connects a hamlet to a village/town or another hamlet
> unclassified - connect farms / isolated dwellings to a hamlet/vilage
> or another farm.
>
> This system is internally consistent and works well for rendering, as
> well as for routing.
>
> Thoughts?
> - Joseph
> (I wish I could review this with other Indonesian mappers, but we
> don't have an active forum or mailing list)
>
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-- 
Fernando Trebien



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