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

[Guenther Meyer]

Am Thursday 21 May 2009 schrieb Lester Caine:
> For routing purposes, the speed for each segment of a route is
> important, and for speed I am sure that the ideal situation is that ALL
> highway segments have their speeds assigned ( ADDING VARIABLE for those
> motorway flyover routes which pass over and under the lower speed local
> roads and have traffic flow management )
>
I would propose exactly that, but with zone:traffic, not with maxspeed.
why?

when the maxspeed is tagged directly, I would assume that the limit is 
signposted.

when I find a zone:traffic-tag and a different maxspeed-tag on the same way, I 
would assume that the way lies in that zone, but is has an explicitly 
signposted different limit, which then would be used in a routing application.

that would be an easy understandable and defined way of tagging and using 
those tags.

> While a discussion on ADDING the speed zones applied by other means is
> possibly useful, having to process that data to provide all of the
> options for the routing software seems pointless to me, and so the roads
> within those areas SHOULD simply have their maxspeed set - even if that
> is applied by some blanket area rule initially.
>
right, but the maxspeed should be derived from the zone-tag.
if you use only the maxspeed-tag, than you can't distinguish, if the limit 
comes from a traffic sign or the zone/type of street...



> So while discussing HOW the default speed for roads are calculated is
> important, can we not simply apply that speed without adding another
> layer of complexity?
I wouldn't do that, because it's a derived value depending on a lot of things 
like road type, time of day, weekday, construction sites, ...

ok, you might add this value additionally with a special tag, to give a hint 
to routing applications.

but there are more applications than just routing, to  which that data may be 
useless.
on the other hand the speed limits are defined values (at least in every 
country I have been so far...).




-------------- 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/20090521/55d11724/attachment.pgp>