[OSM-talk] Directional tagging

[Dave Stubbs]

2008/11/28 Martin Norbäck <martin at norpan.org>:
> Hi everybody,
> I'm sure this has been discussed in length before, but I cannot seem
> to find a good way to search the archives. Anyway, I will present my
> thoughts here and you can respond or be quiet :)
>
> I'm trying to fix at least two issues I have.
>
> a) A way that is sort of one-way but allows buses and taxis in the
> opposite direction.
>
> Don't know how to tag them, currently I've just ignored buses and
> taxis and tagged them oneway=yes.


for the cycling equivalent we have cycleway=opposite_lane.

I've been arbitrarily doing psv=opposite_lane for some bus lanes in
London, which may or may not be described as a complete bastardisation
of the access tag... your solution below sounds more sensible to me.


>
> b) 2+1 ways as we call them in Sweden, they are normal ways but have a
> small fence in the middle and 2 lanes on one side and 1 lane on the
> other side. They look like this:
> http://www.vv.se/filer/Vägprojekt/3-Falt.jpg
>
> Now, I want a good way to tag them, and using lanes, you can maybe say
> lanes=3, or lanes=2+1, lanes=2,1, lanes=1+2, lanes=1,2, ... but how to
> interpret that. I'd rather not resort to mapping these as two ways, as
> they are in effect one way, just preventing head on collision. They
> have crossings like a normal road, no ramps, acceleration fields, etc.
>
> I would like a more general mechanism, but yet simple. I propose
> something like this
>
> forward:lanes=2 backward:lanes=1
> (for the sake of the renderer you could also specify lanes=3)

Seems reasonable except for the divider -- I'd do that road as two
separate ways.
We have some roads in the UK which gain a lane and look a bit like
that, but with no direction divider (usually positioned to allow easy
over taking of lorries on hills). Your tagging solution might work for
these quite well.

Dave