[Tagging] junction=approach

Peter Neale nealepb at yahoo.co.uk
Sat Oct 12 14:53:34 UTC 2019

Looking around my local area and trying to fix issues flagged by the iD editor, I came across a number of road sections on the approach to roundabouts, tagged as “junction=approach”.  I can find no documentation in the Wiki to support this usage and it seems illogical to me, as “junction=*” should specify the type of junction.  The iD editor also objects, stating that “junction-=approach” should be a closed way (i.e. an area object).
An instance of this is https://www.openstreetmap.org/way/205996585.  This was created in https://www.openstreetmap.org/changeset/15069009#map=14/52.0589/-0.7514, so I consulted the original mapper via Changeset comments, saying, 
“....if I have consulted the history and changeset correctly, [this changeset] includes a number of instances (e.g. https://www.openstreetmap.org/way/205996585) where you have tagged a road flare approaching a roundabout with "junction=approach". I can find no documentation in the wiki for this tagging and iD raises it as an issue, saying that "Junction=approach" should be a closed way (i.e.a 2-D object, or area). Could you explain why you tagged it this way? What did you mean by the tag? Is it still relevant?”
Mapper @c2r has responded, ---------------------------“I've always tagged roundabout approaches as junction=approach - I must have picked it up from somewhere. Looking at taginfo, there's about 1760 ways tagged as such all over Europe: 
https://taginfo.openstreetmap.org/tags/junction=approach#map although I appreciate that it doesn't appear to be documented - although very little was at the beginning when stuff just sort of evolved.
“The approaches themselves are pretty standard approaches to roundabouts in England, i.e. there is typically a raised centre triangular island, for a few meters in length where the carriageway flares and separates from the centre. It is not an area. I'd always assumed junction=approach was used as a shorthand to prevent navigation software deciding that a U turn at the gore was acceptable, without needing to actually specify it as such.
“I'm not really bothered one way or another as to whether it remains as being a tag or not; whether it is relevant depends on whether it is useful to renderers or to navigation software. However, with the advent of mass aerial imagery and critical mass, I'm not as involved in OSM mapping as I was years ago when GPS traces were needed, although still add the occasional POI/correction so am active in that regard.
“I'd suggest asking for a ruling from the powers that be. It'd presumably be easy to strip the lot from the database programatically if they weren't required/of use.”-----------------
Advice please.
1. How do I obtain a "ruling" on this, or at least a consensus? Is this the correct forum?2.     Is “junction=approach” a useful tag?3. If not, should it be deleted?4. Could this be done automatically, or should it be by hand?5. Should I amend the Wiki entry for “Key:junction” to deprecate, or warn against this usage?

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