[OSM-talk] junction_ref=<whatever>

David Earl david at frankieandshadow.com
Fri Mar 16 15:28:58 GMT 2007

> I think it should be applied to all the ways that make the junction
> (i.e. tagged highway=motorway_link, or junction=roundabout etc.). It
> only makes sense as a node if it is a simple crossroads in a non-dual
> carriageway.

As you'll see on the page, I am not proposing this is a single node in the junction, but a single node introduced near the junction which serves as a label.

The problem about putting it on the ways of the junction is that a renderer can't easily put a little black box with a number in it close to the junction as appears on most motorway maps in the UK, or green in the US etc. It makes rendering this a huge problem which in practice will just not happen. I'm just trying to find a simple, easy to implement way to show the junction number on the map.

At the moment we don't have any coherent way to group Ways together to form a junction other than a roundabout. If we did, I might well agree with you, as the principle is clearly right. But even then, rendering it isn't straightforward. Let's be pragmatic about this, please.

> Also, we need a way to keep junction 12 of the M25 with junction 2 of
> the M3, which are both the same junction, but not allow confusion with
> junction 2 of the M25 or junction 12 of the M3, which are completely
> different places.

My A-Z road atlas shows two separate icons, one labelled 2 and one labelled 12. (My OS 1:250000 atlas just shows 12, ha!) and my AA Big Road Atlas shows 2/12 in one circle.

My proposal accommodates all of these variations very simply and easily.

(God, this is like wading through treacle. It looks very much to me like we're going to do nothing for the sake of not being able to do everything, and miss useful information off the map in doing so).


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