[OSM-talk] Superways again
david at frankieandshadow.com
Fri Mar 16 19:30:12 GMT 2007
> Then I realised that surely we have a method, tagging.
Potential possibly, and with essentially no change which definitely appeals.
Seems rather fragile though, but I had been thinking along these lines in
ways renderers might improve how they show things, and hadn't made the
connection. But also...
> > * If you break a Way at a bridge, you can group the three Ways
> > (either side
> > and the bridge itself) so their commonality (it's the same road)
> > can be
> > represented (and so on along the road).
> highway=unclassified and name="Seddon Road" and postal_code=L19
My road also changes type at the bridge or elsewhere. I have a real example
of this I did yesterday where the named road continues well beyond the
village boundary, so changes to unclassified. But actually, you don't need
this or the postal code - see below re connectedness.
Doesn't mapnik already do something like this (work out a group of ways
which share a common caption) to determine where it puts name captions?
> highway=residential and name="Rabbit Warren" and postal_code=E17
Oh no, I've got to go back and put postal codes in, and I have no idea what
they are :-)
I also have two *different* roads with the same name in CB1. Ouch. (I bet
that causes the Royal Mail some problems too!). Again see below.
> > * If you want to represent a bus route, the route tag in theory
> > allows this,
> > but in practice you can't put more than one route on the same Way,
> > so it
> > can't also be a different bus route or a cycle network route, and
> > the route
> > isn't coherent in any useful way - you have to search for where it
> > goes
> > next. So grouping ways to represent the concept of route would be
> > helpful.
> > Note this means ways can belong to more than one superway.
> Hmm... I'm certainly less sure about this. Bus routes and cycle
> routes should probably be separate tags, but multiple bus routes...
> I'd be tempted to say this is a problem with tags not allowing
> multiple values that we might look at solving.
I think this also needs a concept of ordering, however it is done, though
you might just be able to work it out from the connections.
Maybe in the end multiple tags is the crucial change, not superways.
> Give everything junction_ref=5 and ref=M6
> Actually, another reason that I've just thought that creating
> anonymous groups doesn't solve anything is that they're just that,
> anonymous, how do we then label them? We add tags to them, but what
> if someone creates a group with ref tag "M6", and then someone else
> creates another group with ref tag "M6" in another country, now
> they'll both come up.
Connectedness: You could require them all to join up to constitute a group
(that is, you must be able to reach any way in the group from any other way
only by passing along ways also in the group). There might be two separate
M6 groups quite validly, so long as they don't get intermixed.
> Also, I realise that this all assumes we have ways to filter by tags,
> but I think adding that capability to the API would be a lot easier
> than bringing in a new data type. Also searching by tags can easily
> be added to the editors (and of course is already there in josm,
> though it could probably do with being extended).
I think consumers could probably deal with it. e.g. I'm already going to
have to for my extended search I'm writing (though superways would simplify
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