[OSM-talk] Display names of crossroads

[Andrew Errington]

On Thu, 14 Feb 2013 17:46:45 Floris Looijesteijn wrote:
> On Wed, Feb 13, 2013 at 3:02 PM, Andrew Errington 
<erringtona at gmail.com>wrote:
> > I don't think that's an appropriate way to name it.  It's not a locality,
> > nor
> > is it really a place.  It's a junction, with a name.
> >
> > I think junction=yes and name=* is the best way to record it, the next
> > step would be to get it rendered.
>
> Where would you place this node if it is a more complex crossing?
> Like a crossing of 2 roads with dual carriage ways?

That is a very good question.

If we have a normal crossroads junction (or T) then there is a single node at 
the point where the two ways cross (or meet).

If we have a crossroads with dual carriageways then there are four nodes where 
the roads cross.

In Korea we also have named junctions at overpasses, so the junction name is 
where the two roads cross (or meet) but they physically don't join because 
one road is on a bridge over the other, and there are sliproads to move 
between them.

The first case is very easy.  The single node is tagged junction=yes, and 
name=*

The second case we could tag all four nodes.  Or put a single node in the 
middle, but then it's not obviously related to the junction.  Or put all four 
nodes in a relation.  Or draw a closed way (area) covering the junction.

In the third case we could tag the four nodes at the beginning of each slip 
road.  Or put the nodes in a relation.  Or draw a big area covering the 
entire junction.

Obviously the same applies T-junctions but there are only three nodes.

I could post this question on the talk-ko list and ask what Korean users would 
expect to see.

Unfortunately, I don't think anyone is using the data, so it's hard to know 
exactly what to do until someone uses it and says 'yes, this is great', 
or 'no, this won't do'.  Most of the junctions in Korea /are/ named as 
free-standing name nodes that were brought in in a big import a while ago.  
When I am mapping I usually cross-reference the name node with a photo of the 
sign from the junction and then merge the name node into the physical 
junction node.

Having written this, I think that a combination of single nodes where two ways 
cross, and relations where dual-carriageways cross or there is a bridge and 
slip roads would work well.

Best wishes,

Andrew