[Tagging] Use of crossing:island where crossings and islands are mapped separately

[Jeroen Hoek]

> Where there is a crossing with traffic islands, but the highways forming the crossings and crossing the islands are mapped separately, my assumption has been that crossing:island=no is the correct tagging. 

I agree. My understanding is that you can provide information about 
pedestrian refuges at a crossing in two ways:

* By adding crossing:island=yes to the crossing node, and mapping the 
whole crossing from side to side with footway=crossing on the crossing 
way, including across the traffic island(s)
* By mapping the crossing separately leaving crossing:island out (or 
using 'no'), and mapping the actual crossing bits with separate 
footway=crossing on the ways between side(s) and traffic island(s)

It is my understanding that crossing:island=* only says something about 
the crossing way it sits on (ideally, tagged with footway=crossing), not 
all the crossings part of an intersection.

I've started using footway=traffic_island on the highway=footway for the 
bits in between (the 'pedestrian refuges' or 'traffic islands'). This 
helps other mappers understand the crossing and prevent accidental 
joining of the ways. For data consumers interested in accessibility, the 
mapped length of the actual crossings (tagged with footway=crossing and 
one or more highway=crossing nodes where ways/lanes intersect) can be 
interesting (e.g., for routers to penalize very long crossings without 
traffic islands).

> I haven't used footway|cycleway=traffic_island on the ways crossing the 
> islands, possibly because JOSM and/or Osmose (incorrectly?) complain. 
> Perhaps I should?

JOSM should have stopped complaining about this by now. Values for 
footway=* where whitelisted due to a period where values for sidewalk=* 
where put in footway=* instead (e.g., footway=left). This is still part 
of the validation, but other footway-values are now treated as 
user-defined, which is in line with how footway=* is used.

Does Osmose complain about these?