On 8/3/06, <b class="gmail_sendername">Collinson Mike</b> <<a href="mailto:mike@ayeltd.biz">mike@ayeltd.biz</a>> wrote:<div><span class="gmail_quote"></span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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I've been a passive member of OSM for over a year now and feel that over
the last few weeks it has moved from being a purely experimental
UK-centric system to being a (the!) working worldwide repository of open
source street map data and of collaborative standards. I've
therefore spent a few days to add all my accumulated collection. On
that experience, I feel the one big difficulty I still have as a beginner
is how to systematically describe the Ways that I make in terms that can
be easily used by other members to make maps, navigation systems and
hopefully to show more information on the
<a href="http://www.openstreet.org/" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
www.openstreet.org</a> main page map itself. <br><br>
I'm therefore very interested in a suggestion made by Wollschaf a
couple of days ago and feel it is very elegant, so add some arguments in
favour of it. It solves a number of problems for me mapping outside
the UK and is flexible enough to create a set of "starter" tag
values for beginner's to use and still be useful for complex situations
and new uses.<br><br>
The essence of what Wollschaf said (below) was: use two tags, one for the
administrative classification and one for the physical:<br><br>
waytype=A (2 lanes+ 1 breakdown lane on a motorway, or very wide
road)<br>
waytype=F (1 lane, wide enough for a car)</div></div></blockquote><div><br>One problem with the waytype categorisation is that it tries to encode several physical attributes into one value. It seems to combine the physical width and the number of lanes into one subjective key.
<br><br>The number of marked and usable lanes is often quite distict from the physical width of the road. The presence of a breakdown lane is unrelated to the width or any other characteristic of the road.<br><br>If we are seeking a purely physical description of the roads then shouldn't there be a separate key for each aspect of the road. The following would describe one carriageway of a motorway:
<br>lanes=3<br>width=18m<br>breakdown_lane=yes<br>oneway=yes<br><br>And this would describe a Sydney lane:<br>lane=1<br>width=3m<br><br>One problem with this is that there is no easy way to accurately measure the width of a road with a GPS unit. Maybe the width attribute should allow units other than metres (1 car, 2 trucks, 1 person), or approximate values 0-5m, 5-10m, or even comparative values: very narrow, narrow, normal, wide, very wide.
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wayclass=uk:primary<br>
wayclass=uk:motorway<br>
wayclass=de:autobahn<br>
wayclass=de:bundesstrasse<br>
wayclass=au:stateroute_a (Single carriageway interstate or interregional
primary highways)<br>
wayclass=au:expressway<br><br>
and I'd add a "global" generic wayclass value set that should
be as small as possible and non-overlapping but allowing personal
common-sense judgement:<br><br>
wayclass=expressway or 1 (typically dual carriageway freeway with use
restrictions)<br>
wayclass=primary or 2 (typically arterial and/or heavily used sealed dual
or single carriage way used by long distance traffic or major cross-town
traffic within cities)<br>
wayclass=secondary or 3 (typically reasonably good quality single
carriage way roads [sealed or unsealed according to local custom] linking
smaller towns, moderate traffic)<br>
wayclass=minor or 4 (local use only, ordinarily little traffic)<br>
wayclass=access or 5 (generally short access roads to/in residential
areas, industrial estates, commercial forests, fire trails, tourist
features, expressway service centres etc)</div></div></blockquote><div><br></div>If a small or undeveloped country does not have a road classification scheme why should we presume to impose one. If some small Carribean island has not created any kind of administrative classification of their roads then I don't think we should do it arbitrarily. The physical scheme should be used in this case.
<br><br>IMHO, each set of adminstrative classifications should be mapped exactly and precisely to the administration of the country they belong to. I realise that this could be below country level in some cases. Road classifications in New South Wales might not be the same as Western Australia, so you might need to have
au.nsw:highway=lane, but this might have a different meaning to au.wa:highway=lane.<br><br><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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Why I like it:<br><br>
(1) <b>Not everywhere has a classification system.</b> I'm mapping
in the Philippines which has no publicly visible road classification
system at all that I'm aware of. Using the current system means
that I'm assigning 'highway=' classifications based purely on personal
judgement and whim. I think that is the most powerful argument for
having both tags.</div></div></blockquote><div><br>Physical classification is the way to go here. It would be misleading to attribute highway=primary if the Phillipines administration does not have such a classification.
<br> </div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div>
(2) <b>Administrative classification systems vary</b>. I'm also mapping
in Australia which has a relatively complex administrative classification
of National Routes, Metroads, State Highways M, A, B, C, D, Tourist
Drives with State variations,
(<a href="http://en.wikipedia.org/wiki/Australian_highways" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
http://en.wikipedia.org/wiki/Australian_highways</a>). Mapping the
current 'highway=' values is possible but only approximate and may
differ from person to person. The current system needs
internationalising.</div></div></blockquote><div><br>There should be an administrative classification scheme for each administrative region, whether that is a federation, a state, a territory, an island or whatever the relevant unit of administration. The use of namespaces would help to manage these.
<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div>
(3) <b>Being accurate and informative with the data available.</b>
I wonder if I'm not alone in not scrupulously recording the
administrative classification of a road? Indeed it may not be displayed
on road signs? At the moment I have to guess or leave 50km+ lengths
of road with no clue to map makers about how to display it. With a
'waytype' parameter I can easily remember the width of road and assign
accordingly. Therefore a useful descriptor can always be
captured.</div></div></blockquote><div><br>Renderers need to colour the roads using the adminstrative classification first, but fall back to the physical attributes for roads without one.<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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(4) <b>Beginners.</b> It has taken me a year to be confident about
entering Ways that might be meaningful to map makers, thanks to
<a href="http://wiki.openstreetmap.org/index.php/Map_Features" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
http://wiki.openstreetmap.org/index.php/Map_Features</a> - but I still
scratch my head in many situations. I'm still rather at sea when it
come to practicality for navigation software. With the proposed
system, I think it would be very easy to instruct a beginner: <br>
- Enter
nodes, join them up as segments and mark one-way segments, <br>
- then map
your road names over the top as Ways,<br>
- enter
the 'name' of your Way and what 'waytype' you observed it as being,
<br>
- *If* you
know the classification, add the 'wayclass' too.<br>
- If you
want to go further, refer to xxxxx.<br>
Easy! A low entry barrier and will result in data that can be
displayed in a meaningful way.</div></div></blockquote><div><br>We need to make it easy - there is a lot of mapping to do...<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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(5) <b> Type and class can complement each other for display and
navigation purposes. </b>As an example, Sydney has lots of alleys -
very narrow metalled through tracks often providing access to the rear of
buildings which are clearly worth flagging to route navigation software
as something worth avoiding and missing out or de-emphasizing on map
displays. Using the current 'highway=' classification, I feel I can
only mark them as ''minor', 'unclassified' or 'residential'.
Unfortunately I have exactly the same choice for the nice wide
residential streets around about. So, either I invent a new 'alley'
classification that may not be understood in all cultures or I simply
mark it as 'residential' with a 'waytype' to show it as very
narrow.</div></div></blockquote><div><br>Sydney's lanes are distinct and very characteristic of that city. If they are a recognised road category in Australia or NSW or Sydney then I would suggest au:highway=lane (or au.nsw:highway=lane
or au.nsw.syd:highway=lane). If not then a physical classification would be more appropriate (lanes=1, width=3m).<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div><div>
(6) <b>Elegant. </b>Using 'waytype' and 'wayclass' seems very
elegant and simple to me. Self-obvious and obviously relates to the
usual parent Way. It gets rid of the UK-centric 'highway'
definition. I am British but it has no or different meaning outside that
country and pedantically not really within it, (what about
"Byways"?). <br><br>
(7) <b>Easily backwards compatible. </b> Take 'highway' key, rename it
'wayclass' and either put 'uk:' in front of the current tag values or
convert them to a smaller global set.<br><br>
<b>Variations<br><br>
</b>One alternative mentioned using numbers could also be
combined:<br><br>
wayclass=1<br><br>
where 1:<br>
uk:motorway<br>
de:autobahn<br>
etc<br><br>
I think this has merit from an internationalisation point of view (map
making software won't have to have built in tables of all the
international variations) but may be dangerous when there are mismatches
between countries. I can't think of a good example - perhaps there
are none - but as a thought experiment would a UK motorway be
mapped to a US Interstate Freeway or to a State Freeway?<br><br>
<b>Drawbacks?<br><br>
</b>The only potential drawback I can see so far is to the 'wayclass' in
that in some countries, roads can have more than one administrative
classification. In the US, as I recall, roads can have both
Interstate and State designations That problem though may be more for the
'ref' tag to sort out, the 'wayclass' would just take the more important
one as a single value.<br><br>
Mike<br><br>
<br>
At 09:56 PM 31/07/2006, Wollschaf wrote:<br>
<blockquote type="cite" cite="http://">On Mon, 31 Jul 2006 11:50:44
+0100, Etienne wrote:<br><br>
<br>
> I think in this context (Street Maps) we should really be
considering<br>
> administrative classifications. OSM can accommodate
physical<br>
> characteristics but that, to me, seems secondary for the most common
kind<br>
> of uses of OSM data.<br><br>
In my opinion it is important to have both. Route planning software
can<br>
make better decisions if the physical properties are known. Looking
at<br>
<a href="http://maps.google.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">maps.google.com</a> (teledata maps) in my area, there are so many roads<br>
rendered as if you could actually drive on them. In reality, you can't
-<br>
one car coming from the other direction and both are terribly stuck.
Using<br>
my route planning software, I've been sent through vineyards several<br>
times. Usually, bigger roads were nearby that obviously were
classified<br>
the same way, perhaps as minor. Currently, I can't do better in
OSM.<br><br>
What should I tag a secondary road with that's several times bigger
and<br>
faster to drive on than the primary road nearby, thus clearly being
the<br>
preferred way to travel?<br><br>
I think we need two sets of tags: one for physical properties and one
for<br>
the administrative classification, based on a scheme for every
country.<br>
This way everything can be tagged. Not every country is as ordered as
we<br>
are used to. I have severe trouble to fit the current highway values
to<br>
the roads I created in Sardinia, Italy. A lot of interpretation is
needed<br>
to fit the tags to the roads, and by reading a map created out of
the<br>
guesswork misunderstandings will occur.<br><br>
To make OSM better than commercial map suppliers, we need as much
metadata<br>
as we can get. Physical road properties will definitely improve the
maps.<br><br>
Examples for a separated way classification:<br><br>
waytype=A (2 lanes+ 1 breakdown lane on a motorway, or very wide
road)<br>
waytype=F (1 lane, wide enough for a car)<br>
wayclass=uk:primary<br>
wayclass=uk:motorway<br>
wayclass=de:autobahn<br>
wayclass=de:bundesstrasse<br><br>
Administrative classification could then also be used to set
permissions<br>
and speed limits, which is currently not possible because of the
diversity<br>
of rules in different countries.<br><br>
Perhaps the tag values should be all in english, to improve readability.
I<br>
would not want to write software using all these tags without<br>
understanding the language behind. The tag value names are not as<br>
important as the correlation... numbers are sufficient, but hard to<br>
remember.<br><br>
Wollschaf<br><br>
**wondering now about highway=us:highway, and why whether just to
remove<br>
the high in way to make more sense. We're just dealing with ways,
aren't<br>
we?<br><br>
<br><br>
<br><br>
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