[OSM-talk] Turn restrictions ambiguity

[SteveC]

On 23 Apr 2009, at 12:34, Tobias Knerr wrote:

> SteveC wrote:
>> On 23 Apr 2009, at 12:17, Teemu Koskinen wrote:
>>> If both from and to ways continue after the via point and neither is
>>> one-way, there's two possible ways to interpret it: the restriction
>>> could apply when coming from either of the ends of the from-way.
>>> This of course doesn't matter if there is similar restriction coming
>>> from both directions, but that's not nearly always the case. And
>>> even if there is symmetry in the real life restrictions, it's not
>>> appropriate in my opinion to map those with just one restriction.
>>
>> eh? don't you assign direction by saying 'from' and 'to' ?
>
>       |A
>       |
>       |
>      x|     B
> -------*------
>       |
>       |
>       |
>
> Imagine this situation, ways A and B with a common node x. You are
> moving on A from north to south and are not allowed to turn into B. If
> you create a restriction "no_left_turn from A to B via x", you will  
> also
> prevent that cars moving from south to north on A can turn left.  
> This is
> usually not intended.

Ah gotcha!

Ok so in that case... why don't we make best practice to split your  
way A in to two directions, rather than hundreds of little ways?


Best

Steve