[Tagging] Mapping as two ways or one, u-turns

Markus Lindholm markus.lindholm at gmail.com
Sun Mar 4 10:20:39 GMT 2012

On 3 March 2012 10:07, Vincent Pottier <vpottier at gmail.com> wrote:
> Le 03/03/2012 08:49, Erik Johansson a écrit :
>> There is nothing separating this road yet it is mapped as two ways:
>> http://osm.org/go/0bCzcBhNM--?m
>> http://goo.gl/KLTpu  (Streetview)
> IMHO, it's a mistake.
>> This is done for routers. Imagine you want to go from the marker to
>> number 117, as it is mapped today the router will know that you can't
>> go back on the same street directly. How can this be mapped with out
>> mapping this as two ways, as it's said in the Editing standards:
>> http://wiki.openstreetmap.org/wiki/Editing_Standards_and_Conventions#Divided_highways
> IMHO, there is a lack of a tag saying that the road can't be crossed, except
> at crossings e.g. tag:crossable=no.
> If it is forbiden to U-turn it at a cross, a restriction relation must tell
> it, or maybe a different tag if all crossings  are concerned, e.g.
> tag:crossable=not_at_all.

There was a proposal like that
that has been abandoned. Not sure of the reason.

I think that having separate ways for legally separated opposing lanes
is the best scheme currently to represent the truth on the ground.

Disclosure: I'm the one who mapped Hornsgatan as it is today.


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