Pierre,
As a European mapper based in the USA, I'd just like to add my support here to
what you are saying, and hope to clarify a little bit.
I think the methodology described in the Wiki for mapping highway tags is very
much based on a 'Euro-centric' approach - The relationship between the quality
of the road and it's importance is implicit, and certainly from where I
originate from, the UK, there is nowhere that a normal person can get to
without travelling a well-maintained, paved road.
Its often difficult for a European to imagine that important roads can be
terrible. It's surprising to learn, for example, that more than 50% of public
roads here in Colorado are unpaved, and subject to many of the issues, such as
bridge wash-outs, impassibility when wet etc, that simply do not occur in
Europe.
Putting this into context, in the Wiki, the description for a secondary road is:
Administrative classification in the UK, generally linking smaller towns and
villages
and the description for a tertiary road is:
A "C' road in the UK. Generally for use on roads wider than 4 metres (13') in
width, and for faster/wider minor roads that aren't A or B roads. In the UK,
they tend to have dashed lines down the middle, whereas unclassified roads
don't.
Here in Colorado, outside of urban areas, i.e. 95% of the state, whilst every
town might be served by 2 paved secondary roads (generally north-south /
east-west), any cross-connectors would be a tertiary road, but would likely be
unpaved. Use of these tertiary roads might save 100's of kilometers in travel
distance, so they must be mapped as tertiary so that mapping and routing
software can use them correctly, even though they absolutely don't match the
Wiki criteria for that road type
I recognize that this issue is even more distinct in Africa, where even primary
roads may meet the Wiki Criteria for "highway=track /
tracktype=grade5/smoothness=catastrophic".
My solution for the Wiki:
1. Eliminate any reference to a road standard in a particular country
(if necessary branch it off to a country-specific page)
2. Eliminate any reference to the quality of the road surface (if
necessary branch it off to a country-specific page)
3. Keep the definition for Motorway - this is pretty much the
definition worldwide
4. Below that, define each type of road by the importance of the
route. Criteria could be, for example, population of city served, length of
route, whether any reasonable alternative routes exist.
e.g. road definitions could be simply:
Primary: A road that is connected to a population center of at least 100000
inhabitants, or is connected to a seat of government, or is at least 200km long
Secondary: A road that is connected to a population center of at least 10000
inhabitants, or is at least 100km long, or connects a primary road to another
public road
Tertiary: A road that is connected to a population center of at least 1000
inhabitants, or is at least 50km long, or connects a secondary road to another
public road
etc, etc
I think it's important to make OSM definitions usable and consistent
worldwide, and this one is really important
Regards
Mark
________________________________
From: Pierre Béland <[email protected]>
To: Martin Koppenhoefer <[email protected]>
Cc: "[email protected]" <[email protected]>
Sent: Wednesday, January 8, 2014 7:58 AM
Subject: Re: [OSM-dev] Renderer issue: highway=service and service=driveway?
Martin
The images in the Highway tag usage wiki page give implicitely instructions to
take care of the quality of the road to classify. But it is stated at the
beginning of the page, that it is sometimes useful to adapt highway tag usage
to the local physical conditions. And this is the case for many countries from
the south where road conditions are quite different from what we expect in
countries from the north.
While mapping for Mali, we were confronted with mappers not able to classify
properly the roads. Too many were identified as tracks. In fact, we have to
think differently from countries of the north. For
example, north of Mali, you have major roads not paved and badly
damaged at the rainy season. They are still major roads and should be
classified this way.
The Highway_Tag_Africa page insist on a simple hierarchy to classify the roads.
We make a clear distinction between the hierarchy and the condition of the
road. Other tags are used to take care of the surface and road conditions. In
later discussions on the HOT list, people suggested that this apply to a
majority of countries from the south. In fact, we often have roads badly
classified. People working for HOT activations agree in general that these
rules are adapted to the context of the countries were we work.
Pierre
________________________________
De : Martin Koppenhoefer <[email protected]>
À : Pierre Béland <[email protected]>
Cc : Greg Troxel <[email protected]>; "[email protected]"
<[email protected]>
Envoyé le : Mercredi 8 janvier 2014 7h30
Objet : Re: [OSM-dev] Renderer issue: highway=service and service=driveway?
2014/1/8 Pierre Béland <[email protected]>
In this particular case, if there was a hierarchy of roads, it would be less a
problem if the rule that I proposed was followed. See
https://wiki.openstreetmap.org/wiki/Highway_Tag_Africa
I don't understand this page. Not that I had objections with what I read there,
but it is a duplication of what is already set. Why "Africa"? We should have
(and do have) a global system to tag and classify roads, bridge=yes and layer=1
are nothing special to Africa, neither is a hierarchical road system. My
suggestion is to delete the page or link to the specific pages in to keep the
wiki maintainable. Duplicating the same information over and over again has no
sense and raises the risk for inconsistencies.
cheers,
Martin
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