[Tagging] Tagging U-Turns (Was: [OSM-talk] Divided/Non-Divided Intersection)

[Alan Mintz]

At 2010-07-23 18:53, John Smith wrote:
>On 23 July 2010 23:48, Alan Mintz <Alan_Mintz+OSM at earthlink.net> wrote:
> > I spend a totally unreasonable amount of time mapping turn restrictions
> > (mostly no-u-turn) as it is, and even that is hard to justify.

I was trying to say that it takes far too long to create this relation, 
which is necessary on maybe 25% of the intersections I'm mapping.


>I guess this goes back to the default values for a
>region/state/country, but in Australia some states have it so that
>it's legal to do U-turns unless signed otherwise, and other states
>have it illegal to do U-turns unless it's signed...
>
>Should we be tagging where it's allowed or where it's not allowed or
>where it's signed specifically one way or the other?

Tag where it's signed, which is generally the exception to the default. In 
places where the law is no-U-turn by default, I would expect to see "U-turn 
OK" signs where they are allowed. In places where the law is that U-turns 
are allowed by default, I see "no U-turn" signs where they are disallowed.

It seems that navigation software needs to know which is the default, 
though. Yet another case for tagging defaults on admin boundaries.

--
Alan Mintz <Alan_Mintz+OSM at Earthlink.net>