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

[Guenther Meyer]

Am Wednesday 20 May 2009 schrieb Greg Troxel:
>   In my part of Australia, we have a speed limit that applies to every
>   non-rural street that is not specifically signed as being another
>   speed - basically case (b) below.  The wording used in the law is
>   "built up area".  (In practice, the test for a "built up area" seems
>   to be "does it have street lights?".)
>
> From my experiences in the US and Ireland, I think there are two
> distinct concepts for speed limits.
>
> In the US (at least in mass), the speed limit is 30 mph (on unposted
> roads) if they are "thicky settled", which is defined:
>
>   "Thickly settled or business district'', the territory contiguous to any
>   way which is built up with structures devoted to business, or the
>   territory contiguous to any way where the dwelling houses are situated
>   at such distances as will average less than two hundred feet between
>   them for a distance of a quarter of a mile or over.
>
> and 40 mph on other roads if not divided, and 50 if divided.  In
> practice almost higher-speed roads are individually posted.  This sounds
> like the Australian situation.
>
> In Ireland, there were signs on all roads leading into villages denoting
> a limit inside (50 kph?) and outside (100 kph?).  While it seemed the
> signs roughly corresponded to built-up areas, it seemed clear that the
> rules were about inside/outside the signs, not about the inter-house
> distance.
>
> The tricky part about "thickly settled" is that adding a house can
> change the speed limit, with no sign.  But I think that's irrelevant for
> OSM purposes.
>
> I think it makes sense to have polygons for formal speed zones, where
> one can see signs on the ground.
>
> For other roads, I think it will make more sense to work on a way to
> measure prevailing speeds from gpx and upload tags that represent what's
> typical.  For residential roads that you don't use to get anywhere,
> having the speed tags right for routing doesn't matter much, and for
> through roads reality is more important than the posted rules.
I would use those tags only for legal restrictions, not for "statistical" 
speeds...
and only for parts of the streets where no traffic sign specifies the limit.

we in germany have the three base zones I mentioned, but it's no problem tom 
extend these for countries with more basic settings...




-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20090521/6fa281f2/attachment.pgp>