[Tagging] Dispute prevention: meaning of lanes tag

Martin Vonwald imagic.osm at gmail.com
Sun Apr 22 08:32:28 BST 2012

2012/4/21 Philip Barnes <phil at trigpoint.me.uk>:
>> You can Tag lanes:forward= and lanes:backward=
> Would this make sense?
> Lanes=3
> Lanes:forward=2
> Lanes:backward=2

No, it wouldn't. This was one of the reasons, why I suggested an
additional suffix "both-ways" in the original version of the lanes
proposal (see [1]). With this suffix you would tag this as follow:

What you are now missing is the information, what exactly can be done
on the both_ways-lane: is it a passing, median or reversible lane?
Originally I suggested an additional tag "reversible" for this.  But
this was ambiguous so when I wrote a proposal for this I changed the
tag to "two_way_lane" (see [2]). Then you could either use the lanes
suffix or the both_ways suffix to specify the kind of lane. Using the
both_ways suffix we would add the following to the aforementioned

Now it is defined, that the lane in the middle is a passing lane. But
there are two reasons, why I think, that two_way_lane is not a good
1) "two_way_lane:both_ways" is awful and two_way_lane makes only sense
with both_ways, but not with forward or backward.
2) A more generic tag could be better readable and at the same time
provide more information with amore compact style.

So I am thinking of renaming two_way_lane to lane_kind. This tag then
should specify the kind of lane, e.g. passing, reversible, median but
also directional for "normal" lanes, and some more. If we have a road
with four lanes and two of them are reversibles, we would tag them as

We would need the tags with the lanes suffix then only in such cases,
where we really need the layout of the lanes, e.g. on junctions. In
this context the values of lane_kind for "normal" lanes then would be

But this all is off-topic right now: for the lanes article I will add
a statement, that this issue is currently unresolved.


[1] http://wiki.openstreetmap.org/wiki/Proposed_features/lanes_General_Extension/ProposalPreVoting#Center.2Fmedian_turn_lanes
[2] http://wiki.openstreetmap.org/wiki/Proposed_features/two_way_lane

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