[OSM-talk] [Tagging] - RFC - Motorway_link implies oneway=??

[Ed Loach]

> versus implying it to be oneway=no, there's *probably* a
> reduction in
> the amount of tagging needed, because there are probably more
> ways with
> motorway_link that are oneway=yes than oneway=no.  In addition,
> for a
> routing application it increases safety.  It's a lot worse to
> route
> someone the wrong way up a one-way motorway_link because it was
> assumed
> to be two-way than it is to send someone on a longer/slower
> route
> because it was assumed to be one-way.

There are a lot of "probably"s there. Based on the fact that there
already a lot of motorway_link's in the database, some of which are
'probably' already explicitly tagged, perhaps it is best to use
explicit tagging, and let the routing software make it's own
assumptions about whether to use a motorway link without explicit
tagging or not. The oneway tags, especially if =yes) should be
stated explicitly, whether we are tagging for routers, renderers or
just mapping what is there... Anyway, if a motorway_link only links
from a twoway road to a oneway motorway way there will be no use
routing down it anyway. Do people actually add oneway roads and
forget to tag them as such?

Ed