Clarification unclassified vs residential

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Clarification unclassified vs residential

Florian Lohoff-2

Hi,
i found some changesets downgrading streets to unclassified. After some
discussions the mapper were under the impression that unclassified is
something higher priority than residential.

From my long tagging practice in OSM unclassified and residential are
identical in respect to priority. (And e.g. OSRM treats them equal)
The first is used as a connecting road off city limits. The latter is
used for the lowest class roads within city boundarys (Where there is
residential usage)

So for me retagging residential to unclassified is broken under the
assumption that unclassified is something "better" than residential.

It is even more broken when there is residential usage in which case
unclassified is inappropriate.

While discussing i found that there was some modification to the German
version of unclassified not saying that unclassified is something
"better" but suggesting that an unclassified should be dragged into
city limits until the next higher class street. This lets user
assume that unclassified is some higher priority than residential.


I was treating those streets identical for the last 10+ years and only
the city limits gave the indication whether to use unclassified or
residential.

Am i wrong with that usage?

Flo
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Re: Clarification unclassified vs residential

AlaskaDave
That is a most interesting question. 

Here in Thailand I interpret their differences, perhaps incorrectly, as residential meaning a way with houses on it, while an unclassified highway is one step below a tertiary and therefore one step above a residential. It does not have many houses (residences) and is often a connector between minor towns or villages. Which is more important? In my opinion, an unclassified highway would offer faster transit times than a residential so I'm surprised to learn that routers rate them the same.

It's a tricky distinction. I hope this thread will help clarify that distinction.

On Wed, Feb 20, 2019 at 4:24 PM Florian Lohoff <[hidden email]> wrote:

Hi,
i found some changesets downgrading streets to unclassified. After some
discussions the mapper were under the impression that unclassified is
something higher priority than residential.

From my long tagging practice in OSM unclassified and residential are
identical in respect to priority. (And e.g. OSRM treats them equal)
The first is used as a connecting road off city limits. The latter is
used for the lowest class roads within city boundarys (Where there is
residential usage)

So for me retagging residential to unclassified is broken under the
assumption that unclassified is something "better" than residential.

It is even more broken when there is residential usage in which case
unclassified is inappropriate.

While discussing i found that there was some modification to the German
version of unclassified not saying that unclassified is something
"better" but suggesting that an unclassified should be dragged into
city limits until the next higher class street. This lets user
assume that unclassified is some higher priority than residential.


I was treating those streets identical for the last 10+ years and only
the city limits gave the indication whether to use unclassified or
residential.

Am i wrong with that usage?

Flo
--
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Chiang Mai, Thailand
Travel Blog at http://dswarthout.blogspot.com

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Re: Clarification unclassified vs residential

Georg Feddern-2
In reply to this post by Florian Lohoff-2
Am 20.02.2019 um 10:22 schrieb Florian Lohoff:
So for me retagging residential to unclassified is broken under the
assumption that unclassified is something "better" than residential.

It is even more broken when there is residential usage in which case
unclassified is inappropriate.

While discussing i found that there was some modification to the German
version of unclassified not saying that unclassified is something
"better" but suggesting that an unclassified should be dragged into
city limits until the next higher class street. This lets user
assume that unclassified is some higher priority than residential.


I was treating those streets identical for the last 10+ years and only
the city limits gave the indication whether to use unclassified or
residential.

Am i wrong with that usage?

Even the english wiki says:
"The tag highway=unclassified is used for minor public roads typically at the lowest level of the interconnecting grid network."

As part of the interconnecting grid network it should connect to at least unclassified or higher roads - unless it is a dead end settlement.
Tagging a through connecting road only because it is inside a city limit as residential makes no sense.
And usually a connecting road from outside a city limit has at least a bit more traffic as an inner-city-only residential.
So the conclusion an unclassified has a bit higher priority than a residential is not far from reality.

Otherwise there is often the problem to tag the main access roads inside a bigger residential area.
The practice to tag those as unclassified for a bit higher priority may not be optimal - but suitable.

This discussion - and usage - is some years old now - and I thought you had at least knowledge of it from the german forum.

Georg

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Re: Clarification unclassified vs residential

AlaskaDave
While I agree with Georg's assessment in general, I want to point out that in Thailand I often do downgrade an unclassified highway when it enters a residential area because the differences between the two ways can be significant. You will be driving along on a nice, smooth, two-lane highway and when it enters a hamlet it might transform into a very narrow one-lane street lined with houses. My intent when tagging is to indicate that the highway when it passes through a town is not in any way a high-speed thorofare. I was under the impression that "downgrading" it to residential would help routers evaluate various alternative routes better.

So, yes, I do perceive an unclassified highway to be more significant than a residential highway in several ways, speed, convenience, and also safety.

On Wed, Feb 20, 2019 at 5:05 PM Georg Feddern <[hidden email]> wrote:
Am 20.02.2019 um 10:22 schrieb Florian Lohoff:
So for me retagging residential to unclassified is broken under the
assumption that unclassified is something "better" than residential.

It is even more broken when there is residential usage in which case
unclassified is inappropriate.

While discussing i found that there was some modification to the German
version of unclassified not saying that unclassified is something
"better" but suggesting that an unclassified should be dragged into
city limits until the next higher class street. This lets user
assume that unclassified is some higher priority than residential.


I was treating those streets identical for the last 10+ years and only
the city limits gave the indication whether to use unclassified or
residential.

Am i wrong with that usage?

Even the english wiki says:
"The tag highway=unclassified is used for minor public roads typically at the lowest level of the interconnecting grid network."

As part of the interconnecting grid network it should connect to at least unclassified or higher roads - unless it is a dead end settlement.
Tagging a through connecting road only because it is inside a city limit as residential makes no sense.
And usually a connecting road from outside a city limit has at least a bit more traffic as an inner-city-only residential.
So the conclusion an unclassified has a bit higher priority than a residential is not far from reality.

Otherwise there is often the problem to tag the main access roads inside a bigger residential area.
The practice to tag those as unclassified for a bit higher priority may not be optimal - but suitable.

This discussion - and usage - is some years old now - and I thought you had at least knowledge of it from the german forum.

Georg
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Re: Clarification unclassified vs residential

Florian Lohoff-2
In reply to this post by Georg Feddern-2

Hi Georg,

On Wed, Feb 20, 2019 at 11:03:15AM +0100, Georg Feddern wrote:
> Even the english wiki says:
> "The tag highway
> <https://wiki.openstreetmap.org/wiki/Key:highway>=unclassified is used for
> minor public roads typically at the lowest level of the interconnecting grid
> network."

Yes - An unclassified road is a road which does not have any
classification. As does a residential not have a classification.

        "Unclassified roads have lower importance in the road network
        than tertiary roads, and are not residential streets or
        agricultural tracks."

Lower importance than tertiary - NOT residential. No word about
beeing of higher importance than residential.

When you continue reading the distinction is that you MAY use an
unclassified in city limits when there is no residential usage.

        "Public roads of low importance within town and cities that are not
        residential may also be highway=unclassified."

For me this means that 99% of the roads within city boundarys cant
be unclassified because there is residential usage.

> As part of the interconnecting grid network it should connect to at least
> unclassified or higher roads - unless it is a dead end settlement.
> Tagging a through connecting road only because it is inside a city limit as
> residential makes no sense.

Why not? This enables a routing engine to assume different
characteristics of roads.

> And usually a connecting road from outside a city limit has at least a bit
> more traffic as an inner-city-only residential.

Have you had a look at the original example images for an unclassified?

https://wiki.openstreetmap.org/wiki/File:Highway_unclassified-photo.jpg

I would not expect more traffic here - I'd expect less.

> So the conclusion an unclassified has a bit higher priority than a
> residential is not far from reality.

Not in my reality and not in the original OSMs reality. Yes - through
misleading statements in the German article this might have influenced
at least the German community to assume otherwise - This is why
i request clarification.

> Otherwise there is often the problem to tag the main access roads inside a
> bigger residential area.

The region where i map mostly we agreed that we may tag roads with clear
interconnecting character and wider lanes with one class higher than
they would have by assuming the strict classification. We agreed
that the causes by which we tag higher be placed in a note= tag on
the road.

So a large wide interconnecting road within city limits might be
a tertiary.

> The practice to tag those as unclassified for a bit higher priority may not
> be optimal - but suitable.
>
> This discussion - and usage - is some years old now - and I thought you had
> at least knowledge of it from the german forum.

My knowledge and usage predates the German Forum by years - I was astonished
finding statements in the German article for unclassified which do not match
(but oppose) the English versions which i typically use and prefer.

Its not the first time i find the German articles to contain a hidden
agenda bei a minority or single mappers trying to steer the community.

Flo
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Re: Clarification unclassified vs residential

Peter Elderson
It's a bit of a mess in Nederland as well - lots of small residential roads have once been imported as unclassified, under the assumption that unclassified means there is no official classification. Which was wrong because unclassified is in fact a classification. As a result, unclassified in OSM in Nederland now says that the classification is not known: anything below tertiary can be unclassified. 

You cannot deduct anything from unclassified. 

Residential just means it has housing along the road.

Unclassified roads within a residential area are probably (but not always) residential. 

Routing cannot rely on this. I would not rely on a router if it relies on this tag.

Fr gr Peter Elderson


Op wo 20 feb. 2019 om 12:08 schreef Florian Lohoff <[hidden email]>:

Hi Georg,

On Wed, Feb 20, 2019 at 11:03:15AM +0100, Georg Feddern wrote:
> Even the english wiki says:
> "The tag highway
> <https://wiki.openstreetmap.org/wiki/Key:highway>=unclassified is used for
> minor public roads typically at the lowest level of the interconnecting grid
> network."

Yes - An unclassified road is a road which does not have any
classification. As does a residential not have a classification.

        "Unclassified roads have lower importance in the road network
        than tertiary roads, and are not residential streets or
        agricultural tracks."

Lower importance than tertiary - NOT residential. No word about
beeing of higher importance than residential.

When you continue reading the distinction is that you MAY use an
unclassified in city limits when there is no residential usage.

        "Public roads of low importance within town and cities that are not
        residential may also be highway=unclassified."

For me this means that 99% of the roads within city boundarys cant
be unclassified because there is residential usage.

> As part of the interconnecting grid network it should connect to at least
> unclassified or higher roads - unless it is a dead end settlement.
> Tagging a through connecting road only because it is inside a city limit as
> residential makes no sense.

Why not? This enables a routing engine to assume different
characteristics of roads.

> And usually a connecting road from outside a city limit has at least a bit
> more traffic as an inner-city-only residential.

Have you had a look at the original example images for an unclassified?

https://wiki.openstreetmap.org/wiki/File:Highway_unclassified-photo.jpg

I would not expect more traffic here - I'd expect less.

> So the conclusion an unclassified has a bit higher priority than a
> residential is not far from reality.

Not in my reality and not in the original OSMs reality. Yes - through
misleading statements in the German article this might have influenced
at least the German community to assume otherwise - This is why
i request clarification.

> Otherwise there is often the problem to tag the main access roads inside a
> bigger residential area.

The region where i map mostly we agreed that we may tag roads with clear
interconnecting character and wider lanes with one class higher than
they would have by assuming the strict classification. We agreed
that the causes by which we tag higher be placed in a note= tag on
the road.

So a large wide interconnecting road within city limits might be
a tertiary.

> The practice to tag those as unclassified for a bit higher priority may not
> be optimal - but suitable.
>
> This discussion - and usage - is some years old now - and I thought you had
> at least knowledge of it from the german forum.

My knowledge and usage predates the German Forum by years - I was astonished
finding statements in the German article for unclassified which do not match
(but oppose) the English versions which i typically use and prefer.

Its not the first time i find the German articles to contain a hidden
agenda bei a minority or single mappers trying to steer the community.

Flo
--
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Re: Clarification unclassified vs residential

AlaskaDave
I think a major purpose of this discussion should focus on assigning the relative "importance" of highway=residential and highway=classified once and for all. If we can come to agreement on what is meant by the two tags, we can better formulate guidelines that ideally will end up in the Wiki someday.

I know for me, there is confusion about it, and I bet I'm not alone.

On Wed, Feb 20, 2019 at 7:25 PM Peter Elderson <[hidden email]> wrote:
It's a bit of a mess in Nederland as well - lots of small residential roads have once been imported as unclassified, under the assumption that unclassified means there is no official classification. Which was wrong because unclassified is in fact a classification. As a result, unclassified in OSM in Nederland now says that the classification is not known: anything below tertiary can be unclassified. 

You cannot deduct anything from unclassified. 

Residential just means it has housing along the road.

Unclassified roads within a residential area are probably (but not always) residential. 

Routing cannot rely on this. I would not rely on a router if it relies on this tag.

Fr gr Peter Elderson


Op wo 20 feb. 2019 om 12:08 schreef Florian Lohoff <[hidden email]>:

Hi Georg,

On Wed, Feb 20, 2019 at 11:03:15AM +0100, Georg Feddern wrote:
> Even the english wiki says:
> "The tag highway
> <https://wiki.openstreetmap.org/wiki/Key:highway>=unclassified is used for
> minor public roads typically at the lowest level of the interconnecting grid
> network."

Yes - An unclassified road is a road which does not have any
classification. As does a residential not have a classification.

        "Unclassified roads have lower importance in the road network
        than tertiary roads, and are not residential streets or
        agricultural tracks."

Lower importance than tertiary - NOT residential. No word about
beeing of higher importance than residential.

When you continue reading the distinction is that you MAY use an
unclassified in city limits when there is no residential usage.

        "Public roads of low importance within town and cities that are not
        residential may also be highway=unclassified."

For me this means that 99% of the roads within city boundarys cant
be unclassified because there is residential usage.

> As part of the interconnecting grid network it should connect to at least
> unclassified or higher roads - unless it is a dead end settlement.
> Tagging a through connecting road only because it is inside a city limit as
> residential makes no sense.

Why not? This enables a routing engine to assume different
characteristics of roads.

> And usually a connecting road from outside a city limit has at least a bit
> more traffic as an inner-city-only residential.

Have you had a look at the original example images for an unclassified?

https://wiki.openstreetmap.org/wiki/File:Highway_unclassified-photo.jpg

I would not expect more traffic here - I'd expect less.

> So the conclusion an unclassified has a bit higher priority than a
> residential is not far from reality.

Not in my reality and not in the original OSMs reality. Yes - through
misleading statements in the German article this might have influenced
at least the German community to assume otherwise - This is why
i request clarification.

> Otherwise there is often the problem to tag the main access roads inside a
> bigger residential area.

The region where i map mostly we agreed that we may tag roads with clear
interconnecting character and wider lanes with one class higher than
they would have by assuming the strict classification. We agreed
that the causes by which we tag higher be placed in a note= tag on
the road.

So a large wide interconnecting road within city limits might be
a tertiary.

> The practice to tag those as unclassified for a bit higher priority may not
> be optimal - but suitable.
>
> This discussion - and usage - is some years old now - and I thought you had
> at least knowledge of it from the german forum.

My knowledge and usage predates the German Forum by years - I was astonished
finding statements in the German article for unclassified which do not match
(but oppose) the English versions which i typically use and prefer.

Its not the first time i find the German articles to contain a hidden
agenda bei a minority or single mappers trying to steer the community.

Flo
--
Florian Lohoff                                                 [hidden email]
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Chiang Mai, Thailand
Travel Blog at http://dswarthout.blogspot.com

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Re: Clarification unclassified vs residential

Fernando Trebien
In reply to this post by Florian Lohoff-2
On Wed, Feb 20, 2019 at 8:08 AM Florian Lohoff <[hidden email]> wrote:
> Why not? This enables a routing engine to assume different
> characteristics of roads.

To make a routing engine such as OSRM and GraphHopper change its
default assumptions about a road type, please describe the road in
further detail using maxspeed=*, surface=*, smoothness=* and also the
access=* tag hierarchy.

Commercial maps usually do not change highway type on roads that go
through urban areas even if they change their physical characteristics
and legal requirements. Such a situation might be rare in Germany but
it happens in smaller cities in many developing countries (mostly
attributed to disorderly urban growth).

The purpose of highway classification is to clearly identify
thoroughfares (in German,  Durchgangsstraße), that is, the main routes
between places. The main article on the highway tag [1] starts from
this idea (highway=primary connects large towns, highway=secondary
connects small towns, etc.) and then asks mappers to choose a similar
local/recognizable system of roads that approximates this result (eg.
choosing ways of a particular official category, or with special
signage).

The road's classification is not simply a summary of the road's
physical characteristics, even though both are usually correlated and
several country mapper communities have adopted such qualities to
establish their highway classification rules in an attempt to improve
verifiability [2] and reduce edit wars. As an example that physical
qualities do not strictly determine highway class, in Canada trunks do
not have to be paved. [3]

Applications expect each level of the street mesh to be as complete
and connected as possible. Some routing engines (especially older
engines and software running on embedded devices with low CPU/memory,
not the case of OSRM and GraphHopper) employ heuristics that
prioritize following streets of higher classification first. In that
sense, highway=unclassified would work like a level between
residential and tertiary, that is, this kind of routing engine would
avoid computing routes through residential streets unless it cannot
find a route using higher road classes. So if an highway=unclassified
route is interrupted by a string of highway=residential in an urban
area, the engine will avoid considering the through route, it will do
so only after exploring all other alternatives of higher class, and
that may result in a much larger route around that area in the highway
mesh.

I don't know any rendering style that currently differentiates between
residential and unclassified. In functional classification both are
types of local roads. [4]

> > And usually a connecting road from outside a city limit has at least a bit
> > more traffic as an inner-city-only residential.
>
> Have you had a look at the original example images for an unclassified?
>
> https://wiki.openstreetmap.org/wiki/File:Highway_unclassified-photo.jpg
>
> I would not expect more traffic here - I'd expect less.

You can't judge traffic from a single still picture. While I don't
know Germany in such detail, this type of road sometimes will have a
different type of traffic, like fewer cars and more trucks or
tractors, depending on where it appears.

> > So the conclusion an unclassified has a bit higher priority than a
> > residential is not far from reality.
>
> Not in my reality and not in the original OSMs reality. Yes - through
> misleading statements in the German article this might have influenced
> at least the German community to assume otherwise - This is why
> i request clarification.

I'm Brazilian (and mapping here) and I actually find the German
classification rules quite reasonable and inspiring, including this
rule about unclassified=*. As far as I know, as you have said, the
German rules were based on English rules, for which
highway=unclassified simply meant "public roads with no official
class" [5]. It is not very intuitive for those classifying roads
without considering their context though. Rules based solely on
physical appearance often lead to fragmentary highway meshes. See [6]
for a very long discussion on the matter. Not everybody agrees that
fragmentation is a problem.

> > Otherwise there is often the problem to tag the main access roads inside a
> > bigger residential area.
>
> The region where i map mostly we agreed that we may tag roads with clear
> interconnecting character and wider lanes with one class higher than
> they would have by assuming the strict classification. We agreed
> that the causes by which we tag higher be placed in a note= tag on
> the road.

Any information you provide on why you chose a particular
classification helps others verifying your changes and avoids edit
wars. I often use source:highway=* for that purpose, as source:* is
the default tag namespace to express where any tag value came from.
[7]

> > The practice to tag those as unclassified for a bit higher priority may not
> > be optimal - but suitable.
> >
> > This discussion - and usage - is some years old now - and I thought you had
> > at least knowledge of it from the german forum.
>
> My knowledge and usage predates the German Forum by years - I was astonished
> finding statements in the German article for unclassified which do not match
> (but oppose) the English versions which i typically use and prefer.

Everyone's opinion counts, but the German article has had this
information since May 2009. It would be best to check if what's on the
map today is closer to what's in the German wiki or to what you have
been doing.

Regards,

[1] https://wiki.openstreetmap.org/wiki/Key:highway
[2] https://wiki.openstreetmap.org/wiki/Verifiability
[3] https://wiki.openstreetmap.org/wiki/Canadian_tagging_guidelines#Trunk
[4] https://en.wikipedia.org/wiki/Functional_classification
[5] https://en.wikipedia.org/wiki/Hierarchy_of_roads#Unclassified
[6] https://lists.openstreetmap.org/pipermail/talk/2018-February/080155.html
[7] https://wiki.openstreetmap.org/wiki/Key:source

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Fernando Trebien

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Re: Clarification unclassified vs residential

Paul Allen
In reply to this post by Peter Elderson
On Wed, 20 Feb 2019 at 12:25, Peter Elderson <[hidden email]> wrote:

Residential just means it has housing along the road.

That doesn't necessarily work the other way around.  My part of the world has a lot of
ribbon villages: a small number of houses (typically around 10)clustered along a
road connecting two towns/villages.  That road might be a primary, secondary or tertiary
route, a minor road or an unclassified road.  I wouldn't classify it as residential even when,
as in some cases, speed limits are lowered where it passes through the village.

In the same way, there is a secondary route passing through the centre  of my town.  If it
weren't also a secondary route it would be classed as residential, but it's a secondary route and
referred to as such on maps.

OTOH, there are many residential roads in my town which aren't dead ends.  Which means you
can use them to avoid the secondary route passing through town.  That doesn't make them an
unclassified route, though.

--
Paul


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Re: Clarification unclassified vs residential

Fernando Trebien
On Wed, Feb 20, 2019 at 9:45 AM Paul Allen <[hidden email]> wrote:
> On Wed, 20 Feb 2019 at 12:25, Peter Elderson <[hidden email]> wrote:
>> Residential just means it has housing along the road.
> That doesn't necessarily work the other way around.

I'm glad you pointed that out. In all that has been said about highway
classification over the years, I've often seen (and sometimes done)
mistakes such as reverse causality (A therefore B equivalent to B
therefore A) and correlation as causality (A and B often appear
together, so if A then B). We need to be careful when interpreting and
discussing the definitions, particularly when talking about other
countries where people have different assumptions. Sometimes even
redundantly clarifying in the wiki that the reverse is not true helps
avoiding this kind of confusion.

The only type of road that by definition cannot have direct access to
private properties is highway=motorway.

In the case of unclassified, the wiki says their > primary < purpose
is to connect hamlets, villages and towns. So they may have houses,
but access to them is not their primary function in the highway system
as a whole. The wiki says: "From experience you know that the road is
frequently and legally used as a through route or to reach a
(non-farm) workplace or tourist attraction." and "The definition of
this tag evolved from a scheme to describe the rather populated
British countryside, where most of the public roads are paved because
they also carry much non-agricultural traffic. The name derives from
the official U classification used by UK local councils, but the OSM
tag has also been applied to roads which carry other official
classifications: the D and C categories in particular. This has
happened because these three official classifications are typically
not signposted and so have historically not been available to OSM
mappers; nevertheless, the tag is still useful for marking
low-importance minor roads." [1]

[1] https://wiki.openstreetmap.org/wiki/Tag:highway%3Dunclassified

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Re: Clarification unclassified vs residential

Greg Troxel-2
In reply to this post by Florian Lohoff-2
The real problem is that if unclassified is more important than
residential, what to do with roads that do not merit unclassified but do
not have primarily residential landuse?



As I see it, in the United States unclassified and residential are
equally important.  However, this is likely to be seen differently by
people especially from the UK, and the tagging scheme carries baggage
in terms of default assumptions about how the world is.

(Leaving out motorways entirely because they seem easy.)

In the UK, we hear about A, B and C roads, and that is encoded in
primary/secondary/tertiary.  We adapt that to roads in other countries
that do not have A/B/C signs.

In the UK, there are also roads that are actually signed as
unclassified, such as "U1274" (wrong number, but I remember an actual
road in Scotland).  There, it seemed there were villages (or towns - not
sure what they call them) that are compact (with 30 mph signs) and then
"not in town" (with circle/slash signs).   I have the impression,
perhaps incorrectly, that roads in villages are "residential" and roads
not in villages are unclassified as a default assumption.

In the US, while we do have more and less congested areas, the notion of
"is this road residential" is often fuzzy.

Then, there are urban roads that aren't particularly important but have
businesses rather than houses.

So all in all I'd say the entire unclassified/residential scheme doesn't
really fit the non-UK world exactly right.  (Really, it's remarkable we
have so little trouble in internationalizing tagging, but then again I
live in "New England", called that for a reason.)

Part of the difficulty is that in the US we use route designators much
more sparingly.  In Massachusetts, we have state highways, which are
sort of like B roads (vs US highway A roads), but we do not have
numbered county roads.  So many roads with merely names are tertiary
because they are how you go from one town to the next.  (Other states do
number county roads.)

One fix would be to declare unclassified more important in the road
network than residential but less than tertiary.  And to add a
road=minor that is exactly equal in important to residential but does
not imply that the preponderance of use is residential.

Or, we could retag residential to minor, as residential landuse can be
encoded with landuse polygons.

Or, use residential to mean minor and ignore the house bit.

Finally, I'd suggest in the US treating unclassified and residential as
exactly the same in importance, because we have no real notion of
unclassified roads like the UK.   That does mean renderers have to treat
them this way, at least in countries that go this way.   (Certainly a
renderer could treat an unclassied road with "ref=U1274" as more
important, as a general practice of emphasizing roads with refs.")





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Re: Clarification unclassified vs residential

Fernando Trebien
On Wed, Feb 20, 2019 at 10:52 AM Greg Troxel <[hidden email]> wrote:
> The real problem is that if unclassified is more important than
> residential, what to do with roads that do not merit unclassified but do
> not have primarily residential landuse?

That's why I think classification should be done by primary
function/purpose, not by a fuzzy (and controversial) concept like
importance. "Importance" begs the unanswered questions: important for
what? for whom?

> Finally, I'd suggest in the US treating unclassified and residential as
> exactly the same in importance, because we have no real notion of
> unclassified roads like the UK.

Do you have any locally-defined highway system that approximately
matches the idea of "a system of highways that generally connects
place=hamlet"?

In Brazil this would generally correspond to municipal roads leading
to the rural areas of municipalities. Some municipal roads, though,
lead to larger settlements within the municipality but isolated from
the main city core, foreign mappers would expect those to be
highway=tertiary and occasionally even highway=secondary, depending on
the type/size of the settlement. These higher classes would often
correspond to a municipally-defined class of highways that are
intended to support more intense/heavy traffic. Often the road will
start paved in the urban settlement (typically branching out of a
tertiary or a secondary highway) and become unpaved for most of its
length outside. So even though there is not a single unifying national
definition/terminology/signage, OSM's highway classes can be matched
to municipal definitions. I've seen edit wars vanish in every place
this idea was applied.

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Re: Clarification unclassified vs residential

Tomas Straupis
In reply to this post by Fernando Trebien
I would agree with those stating importance of road network hierarchy and connectivity (for both routing and cartography).
Having unclassified as higher than residential but lower than tertiary helps a lot.

Maybe google will translate this old post with some practical examples and some technical connectivity checking info:


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Re: Clarification unclassified vs residential

Peter Elderson
In reply to this post by Paul Allen
Exactly. From a routing point of view, if you encounter a residential road, little can be deducted with certaointy
from that tag.
E.g. live very near a residential road, where along the length are lots of houses, but these are shielded by ridges, bushes and separate cycleways  so traffic is not impaired by that, except where there are crossings and traffic signs.


Vr gr Peter Elderson


Op wo 20 feb. 2019 om 13:45 schreef Paul Allen <[hidden email]>:
On Wed, 20 Feb 2019 at 12:25, Peter Elderson <[hidden email]> wrote:

Residential just means it has housing along the road.

That doesn't necessarily work the other way around.  My part of the world has a lot of
ribbon villages: a small number of houses (typically around 10)clustered along a
road connecting two towns/villages.  That road might be a primary, secondary or tertiary
route, a minor road or an unclassified road.  I wouldn't classify it as residential even when,
as in some cases, speed limits are lowered where it passes through the village.

In the same way, there is a secondary route passing through the centre  of my town.  If it
weren't also a secondary route it would be classed as residential, but it's a secondary route and
referred to as such on maps.

OTOH, there are many residential roads in my town which aren't dead ends.  Which means you
can use them to avoid the secondary route passing through town.  That doesn't make them an
unclassified route, though.

--
Paul

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Re: Clarification unclassified vs residential

Florian Lohoff-2
In reply to this post by Fernando Trebien
On Wed, Feb 20, 2019 at 09:39:00AM -0300, Fernando Trebien wrote:

> Applications expect each level of the street mesh to be as complete
> and connected as possible. Some routing engines (especially older
> engines and software running on embedded devices with low CPU/memory,
> not the case of OSRM and GraphHopper) employ heuristics that
> prioritize following streets of higher classification first. In that
> sense, highway=unclassified would work like a level between
> residential and tertiary, that is, this kind of routing engine would
> avoid computing routes through residential streets unless it cannot
> find a route using higher road classes. So if an highway=unclassified
> route is interrupted by a string of highway=residential in an urban
> area, the engine will avoid considering the through route, it will do
> so only after exploring all other alternatives of higher class, and
> that may result in a much larger route around that area in the highway
> mesh.
This is only under the assumption that unclassified is indeed something
"better" than residential which from the original tagging it isnt.

From the original meaning unclassified was the lowest class road in
rural or off city limits. residential was the lowest class road within
city limits. (Assuming that city limits mean residential usage)

Now the German Wiki pages states otherwise - not explicitly that
unclassified is something better but by assuming rules on where to
use it which are contrary to the original meaning of unclassified which
makes users THINK thats its something better.

From OSRM profiles it isnt - So it doesnt make a difference for at least
OSRM.

I dont think that language tagging pages which ought to be translations
start their own agenda and push assumptions which are far off the
original - at least without stating so.

Flo
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Florian Lohoff                                                 [hidden email]
        UTF-8 Test: The 🐈 ran after a 🐁, but the 🐁 ran away

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Re: Clarification unclassified vs residential

Tomas Straupis
2019-02-20, tr, 20:08 Florian Lohoff rašė:
> From the original meaning unclassified was the lowest class road in
> rural or off city limits. residential was the lowest class road within
> city limits. (Assuming that city limits mean residential usage)

  unclassified "original" meaning was "for through traffic". Which is
"better", or in normal terminology - "higher in the road network
hierarchy".
  As for the name "unclassified". Both residential and unclassified
are roads which do not have national reference numbers/classification.

  If unclassified and residential would be identical, what would be
the reason to tag such roads differently?

P.S. Name "residential" is kind of misleading. Because of the lack of
highway type for large arteries in industrial/commercial zones,
residential is used for that in order not to have just "service"
roads, and not to tag them "unclassified" as they are not for
through/important/high traffic.

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Re: Clarification unclassified vs residential

Mark Wagner
In reply to this post by Fernando Trebien
On Wed, 20 Feb 2019 11:30:07 -0300
Fernando Trebien <[hidden email]> wrote:

> On Wed, Feb 20, 2019 at 10:52 AM Greg Troxel <[hidden email]> wrote:
> > The real problem is that if unclassified is more important than
> > residential, what to do with roads that do not merit unclassified
> > but do not have primarily residential landuse?  
>
> That's why I think classification should be done by primary
> function/purpose, not by a fuzzy (and controversial) concept like
> importance. "Importance" begs the unanswered questions: important for
> what? for whom?

Here in Washington State, there are two possible "non-fuzzy"
classification schemes:

1) By usage rules: Motorway/arterial/other.  This isn't very
fine-grained, and doesn't give you a way to distinguish Sprague Avenue
(five lanes one-way) from Queen Avenue (two-way, no lane markings) from
WA-20 (major cross-state highway) from WA-127 (exists only to avoid a
hundred-mile detour when crossing the Snake River).

2) By operator: Interstate highway/US highway/state highway/county
road/other.  This is fine-grained but misleading: for example, WA-520
(a state highway) is a multi-lane divided grade-separated high-speed
controlled-access road -- in short, an Interstate in all but name.

(There's also the state highway department's internal highway
classification system that maps reasonably well to OSM's system, but
you'd have to copy it from their maps -- there's no on-the-ground
evidence that something is an "Urban Major Arterial" or a "Rural Minor
Collector".)

> > Finally, I'd suggest in the US treating unclassified and
> > residential as exactly the same in importance, because we have no
> > real notion of unclassified roads like the UK.  
>
> Do you have any locally-defined highway system that approximately
> matches the idea of "a system of highways that generally connects
> place=hamlet"?

That would be the state highway system: nearly every incorporated
community and most of the unincorporated ones are served by at least
one state highway.  But see the above examples for why calling these
roads "unclassified" is a bad idea.

(And note that all of the above is only fully applicable for Washington
State.  Other states will have other systems, though at least in the
western United States, they don't vary by much.)

--
Mark

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Re: Clarification unclassified vs residential

Jarek Piórkowski
On Wed, 20 Feb 2019 at 14:51, Mark Wagner <[hidden email]> wrote:

> > Do you have any locally-defined highway system that approximately
> > matches the idea of "a system of highways that generally connects
> > place=hamlet"?
>
> That would be the state highway system: nearly every incorporated
> community and most of the unincorporated ones are served by at least
> one state highway.  But see the above examples for why calling these
> roads "unclassified" is a bad idea.
>
> (And note that all of the above is only fully applicable for Washington
> State.  Other states will have other systems, though at least in the
> western United States, they don't vary by much.)

Just to add an example to "classification is difficult":

In Ontario, most small communities are _not_ served by a provincial
highway as a result of administrative reorganizations. We have
distinct communities of 10000 people (Uxbridge, Elmira, Smithville to
give a few examples) which are only served by regional roads (third
administrative step, after federal and province).

--Jarek

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Re: Clarification unclassified vs residential

Sergio Manzi
In reply to this post by Mark Wagner

Hello Mark,

I'm not willing to criticize your contribution, at all, but your preamble, "Here in Washington State ...", was food for thought about the fact that sometimes (often?) we are affected by cultural bias here: the definition of features like highways may differ a lot depending in which part of planet Earth you happen to live. My (Italian) concept of a residential road is surely different from yours (US, Washington State), and one of an Indian citizen (I travelled a lot in India so maybe I have rough idea about that), or a Somali (never put foot there...), just to make a couple of examples.

I think those definitions ar much better left to local communities, and so seems to think "the wiki" too in its incommensurable wisdom: see pages like https://wiki.openstreetmap.org/wiki/Tagging or https://wiki.openstreetmap.org/wiki/Highway:International_equivalence and https://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access-Restrictions

One thing I'm quite sure, anyway, is that "unclassified" should mean just that: "it doesn't fall in any other classification OR we don't know cr.p about it (we know there is a road there, but we don't know how it is)".

Routing decisions too are culture-dependent. As an example, in India I know of some residential roads which are perfectly normal roads by daytime, but are closed to traffic by night time (but maye there is some other kind of more specific restriction for that).

Sergio

On 2019-02-20 20:50, Mark Wagner wrote:

Here in Washington State, ...

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Re: Clarification unclassified vs residential

Fernando Trebien
In reply to this post by Mark Wagner
On Wed, Feb 20, 2019 at 4:52 PM Mark Wagner <[hidden email]> wrote:

>
> On Wed, 20 Feb 2019 11:30:07 -0300
> Here in Washington State, there are two possible "non-fuzzy"
> classification schemes:
>
> 1) By usage rules: Motorway/arterial/other.  This isn't very
> fine-grained, and doesn't give you a way to distinguish Sprague Avenue
> (five lanes one-way) from Queen Avenue (two-way, no lane markings) from
> WA-20 (major cross-state highway) from WA-127 (exists only to avoid a
> hundred-mile detour when crossing the Snake River).
While having the two together side by side

While I think this idea would hold well in developed areas, it may not
in the sparser ones.

> 2) By operator: Interstate highway/US highway/state highway/county
> road/other.  This is fine-grained but misleading: for example, WA-520
> (a state highway) is a multi-lane divided grade-separated high-speed
> controlled-access road -- in short, an Interstate in all but name.

Brazil has the same problem. Some of the federal highways are
motorways with multiple lanes, others are little more than a dirt road
that is not even compacted regularly. Likewise for state highways. And
there are cases where state highways are more developed (more lanes /
better maintenance) than federal highways connecting the same places.

> (There's also the state highway department's internal highway
> classification system that maps reasonably well to OSM's system, but
> you'd have to copy it from their maps -- there's no on-the-ground
> evidence that something is an "Urban Major Arterial" or a "Rural Minor
> Collector".)

Not everything needs to be on the ground. Administrative borders are
only very rarely marked on the ground and we still rely on published
data. So, if it is publicly available, it can be used by mappers,
especially if it produces a satisfying result. In Brazil we use
official municipal maps to classify urban streets in OSM. This data is
spread over the websites of prefectures (one per municipality), so we
gathered the main ones on the wiki to make verification easier by
independent mappers. [6] Just like in highways outside urban areas,
the physical profiles of urban street classes often overlap.

> > Do you have any locally-defined highway system that approximately
> > matches the idea of "a system of highways that generally connects
> > place=hamlet"?
>
> That would be the state highway system: nearly every incorporated
> community and most of the unincorporated ones are served by at least
> one state highway.  But see the above examples for why calling these
> roads "unclassified" is a bad idea.

It may look like that if you think that the route between a pair of
distant hamlets will mostly be made up of state highways. But the
state highway system connects larger settlements as well - place=town,
place=city - and that's probably its main purpose. So I don't think
the system we're looking for is the state highway system. It may help
to think classification top-down: first you connect pairs of very
large settlements using trunks, then you connect pairs of (say)
city-sized settlements using primary ways (without changing any
previously assigned trunks) (also connect cities to the large
settlements of the previous set), then pairs of town-sized settlements
using secondary ways (and town-city pairs, and town-large settlement
pairs), and so on. This is of course tedious, a little subjective, and
error-prone, that's why this result is to be approximated using other
verifiable characteristics.

I queried place=hamlet in Washington State using Overpass Turbo and
compared it with the current classification in OSM. Indeed, many such
places lie next to major highways, as is the pattern in other
countries (small communities tend to sprout near them). But there are
many that do not. For example, Nilles Corner [1] and Osborne Corner
[2] in Douglas County do not. What is generally expected is that the
main route between them is made of ways whose class is
highway=unclassified or higher. The route may overlap with routes
between more important places, say Niles Corner to Fairview [3] whose
main route overlaps with the tertiary WA-17 highway, which (as
generally expected from highway=tertiary) is the main route between a
pair of place=village: Bridgeport [4] and Coulee City [5]. What's
interesting about the roads that connect Nilles Corner and Osborne
Corner is that they do not connect any pair of place=village or
higher, so there's no reason to classify them as any higher than
unclassified. There could be a really nice multi-lane highway between
them, but very few people would be using it. (Of course, there is none
because the demand is very low.)

That's the general idea. The next step is to attempt to find a rule
based on local highway systems (recognizable by Americans, especially
by Washingtonians) which closely produces this general result in most
cases. Comparing existing maps (digital or paper) may help defining
such a rule too. The more you compare (maps/approaches and places),
the more satisfying the agreed rule will be for mappers and users.

In Brazil, for example, as we advance in this discussion, we have
found so far that most pairs of place=city are connected by paved
federal highways and that there's a particular kind of state highway
(officially called "access" or "link" road, not to be confused with
trunk_link) which is typically used to connect place=town. So these
characteristics could eventually be used to produce a reasonable,
although still imperfect classification (what looks really close to
the UK classification is the functional classification published by a
few state highway departments). These qualities are not always
obtained from the "ground" but by jurisdiction (federal vs state) and
type (code higher or lower than 400), shown in most road signs but not
in municipal roads and in most unpaved state/federal roads (usually
without any signs).

In Germany and in the UK, road type is usually identifiable from
highway signs and physical profiles may overlap between types, though
usually they are clearly distinct when the two highways cross or lay
near each other. What they have is essentially a functional road
classification system that is clearly marked by the road signs.

[1] Nilles Corner: https://www.openstreetmap.org/node/150974922
[2] Osborne Corner: https://www.openstreetmap.org/node/150951417
[3] Fairview: https://www.openstreetmap.org/node/150933316
[4] Bridgeport: https://www.openstreetmap.org/node/150948574
[5] Coulee City: https://www.openstreetmap.org/node/150959667
[6] https://wiki.openstreetmap.org/wiki/Category:Cidades_com_hierarquia_vi%C3%A1ria_oficial

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