[OSM-talk] virtual san francisco mapping party?

[Peter Miller]

Thanks for the feedback. Regarding road classifications can I suggest the
following:

 

OSM uses six levels of highway classification for roads for motorised
vehicles going from motorway at the top to unclassified at the bottom. You
could then add byways and bridleways and footpaths to this list but let's
not do that for now.

 

International standards such as GDF also have road classes. Their top one is
called 'main road' and then classes 1-9 in descending order. In GDF these
are called 'National Road Class' to keep the naming of these levels open for
local interpretation. The important thing is that main road is the most
important and class 9 is the least important. Lets refer to the top class as
0 (rather than main road).

 

As you know in the UK these classes are currently encoded using the UK road
classification systems for historical reasons.

 

A problem for the USA and other countries is that the rendering of these
roads is also currently based only on UK practice, so the most important
roads (class 0) are blue, whereas in the US they should be orange. The next
level down is rendered by OSM as green whereas for the US it should be
yellow etc.

 

I notice from current San Francisco mapping that a number of roads a tagged
as 'secondary' which then renders as a comfortable orange colour which
probably makes the US maps look better to local eyes even though in the
class system this is a class 3 road.

 

It seems important therefore to render roads appropriately in each country.
For the UAS I think we need Mapnik and osmarender to render class 0 roads
(tagged as motorways in OSM) as orange in the USA and blue in the UK and
possibly other colours on a national basis. Class 1 roads (tagged as trunk)
also as orange? Then class 2 (tagged as primary) and Class 3 (tagged as
secondary) as yellow. Other classes could be white. Whatever the choice I
think we need a table to relate road class (0-9) to the names various
countries to colours in various countries. 

 

 

Does that make sense?

 

If we don't do this then mappers will be tempted to tag to get the right
visual appearance, rather than the rather classification.

 

 

 

 

Regards,

 

 

 

Peter

 

 

  _____  

From: Karl Newman [mailto:siliconfiend at gmail.com] 
Sent: 14 April 2008 16:09
To: Peter Miller
Cc: SteveC; Talk Openstreetmap; talk-us at openstreetmap.org
Subject: Re: [OSM-talk] virtual san francisco mapping party?

 

On Mon, Apr 14, 2008 at 4:03 AM, Peter Miller <peter.miller at itoworld.com>
wrote:

<snip> 


I have a few specific questions/observations based on the work I have done
so far.


1) The rail network data in the area seems very fragmentary. It may be
valuable for someone with good local knowledge to concentrate on that bit.


Welcome to public transit in the Bay Area. The real system is very
fragmentary with poor coverage... 
 


2) I have cleaned up and completed the BART network. I have tagged it
'subway' which may not be ideal, possibly 'metro' would be better. I am also
not clear if it shares track with Union Pacific through Oakland down to
Hayward. Also, if I say the subway is in a tunnel it is not rendered at all
in Osmarender. Currently it is tagged with layer=-1 without a tunnel tag for
the underground bits. Feel free to improve what I have done.


I agree, "metro" or equivalent would be better. It's really only a subway in
downtown Oakland and SF, and obviously in the trans-bay tube. I'm nearly
100% positive that it doesn't share track with UP. I think it has its own
gauge and everything.

<snip>

4) Nearly all the tiger roads are tagged as 'residential' by default. It
would be very useful to have a mapping of terminology between US names
'interstate' etc, and the OSM ones. I assume 'motorway' = 'interstate'. How
should 'trunk' be interpreted for the USA? What about Primary, secondary
etc?. I suggest that you folk update the map features with your
recommendations and ensure consistency across the USA.


There has been a bit of discussion about this, but there doesn't seem to be
any agreement and the Wiki is a mess with regards to this, with conflicting
information on various pages. Part of the problem comes from us poor US
residents trying to map our road system to the UK/European standard where
many of us have not spent a lot of time (or in my case, I didn't pay
attention to the road classifications). I would say in general,
interstate=motorway, US highway=trunk or primary (or maybe motorway in
certain cases), state highway=primary or secondary, county highway=secondary
or tertiary, road through commercial district=unclassified, and
residential=residential :-)


Karl

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