[OSM-talk] zones for motorway/in town/outof town?

Florian Lohoff flo at rfc822.org
Wed May 20 20:39:49 BST 2009


On Wed, May 20, 2009 at 11:59:05AM +0100, Radomir Cernoch wrote:
> 1) Every road is by default 'rural' road (speed limit 90 km/h).
> 2) Every highway has speed limit 130 km/h by default.
> 3) If a road is inside a polygon tagging the city limits,
>    then its speed limit is set to 50 km/h. Such polygon might be tagged 
>    by 'place', but the actual name of the tag is not important here.
> 4) If a road has different speed limit from rules 1) - 3), it is tagged
>    with 'maxspeed=...'.

The problem with implicit speed limits is that one day someone will rely on
your output and probably just someone only forgot to map at that end of the
road. The best thing to do is to make maxspeed/zone explicit only. The
advantage of a traffic "zone" to maxspeed is that one can derive the source of
the speed limit (and possibly other limits) - In Germany we have a very
widespread "zone 30" culture where not all streets have individual speed limits
but rather the sign limits the speed until you pass the end sign - probably on
a very different road.  Much like city limit signs. The problem now is that you
cant actually work with polygons as for example a motorway could pass over a
zone-30.

Flo
-- 
Florian Lohoff                  flo at rfc822.org             +49-171-2280134
	Those who would give up a little freedom to get a little 
          security shall soon have neither - Benjamin Franklin
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20090520/f010aa78/attachment.pgp>


More information about the talk mailing list