[Tagging] How to tag an imaginary oneway barrier

[Ilpo Järvinen]

On Sat, 1 Feb 2014, Masi Master wrote:

> Am 01.02.2014, 10:05 Uhr, schrieb Pee Wee <piewie32 at gmail.com>:
> 
> > 1 Cut the way where the sign is and use a relation type :
> > restriction<http://wiki.openstreetmap.org/wiki/Relation:restriction>.
> > 
> > 2 Add a node on the way where the sign is and add a motorcar:backward=no to
> > this node. (similar to
> > traffic_sign:forward<http://wiki.openstreetmap.org/wiki/Traffic_sign#As_part_of_a_way>on
> > a node that is part of a way)
> > 
> > 3 Cut the way where the sign is into a tiny piece of way.  Add a
> > motorcar:backward =no  to this tiny piece of way.
> 
> Normally traffic signs belongs to the road to the next intersection/crossing.
> Let's look how we tag maxspeed: From the sign to the next
> sign/intersection/crossing "the whole way". So if you come from a
> residential-driveway or by a u-turn, you can't see the maxspeed limit and you
> can't drive conform to it. So should we tag the maxspeed also at a very short
> section? (Router and other software has to must expand the maxspeed to the
> next intersection.)
> 
> I suggest it is better to add No. 3: motorcar:backward=no
> The sign is there by a reason, and motorcars should not go to this
> road/direction. So OSM-data can give a person/software a bit of "more
> information" to show that the road/direction is "not allowed" (even but from
> beginning).

Which is "oneway" but for some reason it wasnt't marked as such. If 
there's a true oneway street with proper signage, it's actually obvious 
from both ends (just consider the signs specific to oneway case) so you 
"cannot miss it and u-turn". This non-oneway case is no different from 
=destination or a turn restriction in which only a particular route is 
forbidden, not the actual traffic on the road.

Are there some real world examples where a maxspeed for opposing direction 
is really different? (Signage bugs don't count or short sections that 
occur due to sign placement).

-- 
 i.