[OSM-talk] Turn restrictions

Raphael Mack ramack at raphael-mack.de
Thu Aug 16 12:34:19 BST 2007

Am Donnerstag, den 16.08.2007, 10:58 +0100 schrieb Steve Coast:
> On 16 Aug 2007, at 10:29, David Earl wrote:
> > On 15/08/2007 22:48, Steve Coast wrote:
> >> So I'm on a train otherwise I'd link to Andys wiki page he pointed  
> >> to  today, but I want to try out a turn restrictions scheme,
> >> Given a road direction, and roads 'Baker Street' and 'Marylebone   
> >> Road' you tag the way 'Baker Street' with
> >> no_turn_left:'Marylebone Road'
> >> If you can't turn right then it's 'no_turn_right'. If you can't  
> >> turn  at all it's 'no_turn'. And thats it. There are three major  
> >> problems  with this
> >> First, as far as I know JOSM doesn't let you use keys more than  
> >> once  but the API does. So you can't have more than one  
> >> no_turn_left. So fix JOSM.

I don't think JOSM should be changed here. If you allow to have multiple
keys what should be a way with name="Baker Street" and name="Marylebone

> >> Second, what if it's no turn for car but ok for bikes, or  
> >> whatever.  Well, then shouldn't we look at triple tags?   
> >> car:no_turn_left:Marylebone Road ? That is, keyvals now have  
> >> third  string along with key and val? We'd add a third keyval  
> >> property, call  it what you will, and all the current keyvals will  
> >> have that third  proprty set to 'general'. So general:name:Foo  
> >> Street and so on. Then,  this third column can be specialised  
> >> along the lines of Map Features  as the keys and vals are.

Does this really work today? BTW, this is confusing because a key-value
pair is not anymore a pair. And it can be solved with an entity with
from='Baker Street'
and tags:

> > Frederick's prototype for relationships addresses this properly, by  
> > grouping the Ways affected by reference rather than name.
> >
> > See http://openstreetmap.gryph.de/entities/
> Yes but my way is about a billion times simpler, human readable and  
> works today. :-)

I don't think so. When I read the proposal of entities and the examples
on http://openstreetmap.gryph.de/entities/use.html I thought hey cool,
this is nice and clear. And entities work today also. See:

I think Frederik's approach is much cleaner then the hack suggested by
Steve - and solves even more issues.

Have fun,

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