[Tagging] Classifying roads from Trunk to Tertiary and Unclassified

Joseph Eisenberg joseph.eisenberg at gmail.com
Mon Aug 12 16:26:27 UTC 2019

Jumping back in here, I should clarify that I was mainly thinking
about how to help Indonesia and other countries with developing
Openstreetmap communities decide on ways to use the highway
classification tags, when there isn't a national highway class system,
or when it's not obvious how the local system should fit OSM tags.

In rural Indonesia, as in Australia, Canada, Brazil and other
countries with remote, undeveloped areas, there are often roads that
end at a settlement, and are the only way in or out, in contrast to
places in Europe which have complex networks with many different
options from point A to B.

That's the simple case that I was thinking of: if a road ends at a
city at A and it's the only route to the rest of the island, it's
likely to be a trunk road. If it ends at a town, and it's the only
connection from town A to all the other towns in the province, it's
probably a primary road, and so on. This allows mappers to identify
highway classifications based on the network in OSM data plus place=*
classes, which are fairly objective and verifiable (when based on
population plus services).

I actually heard back from one of the HDM/HOT lead mapper in
Indonesia, and he said that they often use a similar system, in more
populated areas like Java which have many roads and clear
administrative boundaries (unlike here in Papua):

"[National roads] "Jalan Trans-" in every island use highway=trunk.
"But personally, for other hierarchy, I recommend using
[administrative] boundaries.:
 - highway=trunk through province boundaries.
 - highway=primary connecting districts [admin_level=5] to cities or towns.
-  highway=secondary connecting city or town to sub-district
(kecamatan) [admin_level=6], connecting two sub-districts, and also
connected with a primary road.
- highway=tertiary connecting sub-district (kecamatan) to village
(kelurahan) [admin_level=7], crossing village boundaries, and also
connected with secondary road
- highway=unclassified connecting between villages, and isolated houses."

See: https://www.openstreetmap.org/changeset/72632172. - I've edited
for clarity.

So that matches my thoughts about matching highway classes with the
settlements they connect as a main route, but also considers if it's
the main road to a whole district, sub-district or (administrative)
village. Generally every province (level 4) has at least 1 city and
each district (level 5) has at least 1 town, so the two ideas usually

So to put it together

0) Motorway
1) Trunk - national roads; the main roads that connect provinces to
other provinces and cities to other cities. Start/end at cities.
2) Primary - main road that connect districts (the level below
provinces) to other districts, and towns to other towns and cities.
Start/end at towns (or cities).
3) Secondary - connect sub-districts to others, and villages to larger
towns, by connecting to a primary road at some point. Not the main
route in a district.
4) Tertiary - connect villages and hamelts to other villages, and
connect to a secondary (or primary) road. Not the main route in a
5) Unclassified - connects hamlets and isolated dwellings to villages
and larger areas, by connecting to a tertiary, secondary or primary
road. Never a major through-route.

- Joseph

On 8/13/19, Paul Allen <pla16021 at gmail.com> wrote:
> On Mon, 12 Aug 2019 at 16:44, Philip Barnes <phil at trigpoint.me.uk> wrote:
>> There is at least one trunk road (green signs) which has a B
>> classification. A6 to M6 near Shap.
>> There's always one.  Sigh.
> I'd expect it to eventually get a new A number.  Possibly with a very large
> value of "eventually."
> --
> Paul

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