[Tagging] Clarification unclassified vs residential

[Fernando Trebien]

On Tue, Feb 26, 2019 at 11:20 AM Martin Koppenhoefer
<dieterdreist at gmail.com> wrote:
>
> Am Di., 26. Feb. 2019 um 13:52 Uhr schrieb Fernando Trebien <fernando.trebien at gmail.com>:
>>
>> On Mon, Feb 25, 2019 at 9:00 PM Sergio Manzi <smz at smz.it> wrote:
>> I think the official categories in Codice della Strada should probably
>> be assigned to OSM's classes by closely matching the descriptions in
>> the wiki.
>
> not at all, we already have classified all of our roads according to wiki, surroundings/context, local knowledge etc.
> If we are to add "Codice della Strada" classes, it should not influence the highway class, it should be an additional tag.

Well, I brought this up because it would be interesting to discuss at
least how is the official classification of roads in Italy inadequate
for OSM's highway=*.

> We might also decide to tag the Italian network classes explicitly. I'm not an expert in this field, but from a quick internet lookup it appears in Italy there are 4 classes of (kind of) movement: a - primary network (transit), b - principal network (distribution), c - secondary network (penetration), d - local network (access).

> You can find more information in this ministrial decrete from 2001 which was issued after the new 1992 CdS law: http://www.mit.gov.it/mit/mop_all.php?p_id=1983
> (this is mainly thought as a reference for the Italian mappers, I do not expect the others to read through 100 pages in Italian).

What's described in pages 5-8 sounds a lot like the main functional
categories used in the US and in Brazil. [1] Starting at page 23 this
document presents some physical profiles of roads. As a developed
country, I would expect this to be quite uniform across Italy. If that
is true, then physical attributes can indeed determine highway=* in
OSM.

Apparently what is different between Italy and Brazil is that Italy
has a unified classification system for the whole country, whereas in
Brazil each municipality can define different physical profiles and
highway classes for its streets and roads (non-municipal roads of
course are more standardized). So, in Brazil, I've had more success
first assigning municipal classes to the national classes, and then
those to OSM. But if classification is done solely by the physical
attributes, then variations between municipalities break the
functional organization of the system, leading to a messy map. Some
Brazilian municipalities or even parts of municipalities have been
built with American standards (wide, straight streets), others
(usually older) with European standards (curvy streets, narrower,
sometimes as narrow as medieval streets).

> For the specific characteristics you must take into account whether the road is inside or outside of a built-up area (this is generally an interesting information for which we do not explicitly cater in general with our tagging, but which should probably be introduced).
>
> When planning a road you must additionally take into account:
> - entity of movement (median distance that the vehicles travel)
> - territorial connecting function (national, interregional, provincial, local)
> - traffic components (light vehicles, heavy vehicles, motorvehicles, pedestrians, etc.)

That's very much what functional classification is all about.

[1] https://en.wikipedia.org/wiki/Functional_classification

-- 
Fernando Trebien