[Tagging] lanes tag dispute

Anthony osm at inbox.org
Sun Sep 18 18:12:16 BST 2011

On Sun, Sep 18, 2011 at 12:59 PM, Nathan Edgars II <neroute2 at gmail.com> wrote:
> On 9/18/2011 12:54 PM, Anthony wrote:
>> On Sun, Sep 18, 2011 at 12:01 PM, Dave F.<davefox at madasafish.com>  wrote:
>>> On 18/09/2011 16:20, Nathan Edgars II wrote:
>>>> Here's an example of what tagging every lane would lead to:
>>>> http://wiki.openstreetmap.org/wiki/File:Silly_lane_count.jpg
>>> I see nothing intrinsically wrong with that. Lots of splitting ways&
>>> tagging admittedly, but that's a problem with OSM&  its tagging process.
>> I agree.  This data would be quite useful to routing software,
>> especially when combined with information about which lanes have which
>> turn restrictions.
> I think to do this properly you'd have to map every lane as a separate way.

Properly or perfectly?  You can get a lot of information from just the
number of lanes and the turn restrictions on each.  Enough for a
router to say "stay in one of the left two lanes".

Yes, mapping every lane as a separate way would be even better, but
let's go one step at a time.

>> Yes, it's a lot of work, and people routinely ignore it, but that
>> doesn't make it wrong.  The way I see it, ignoring short lane number
>> changes is equivalent to ignoring short traffic dividers (e.g.
>> http://g.co/maps/cqdmf).  I wouldn't blame someone for ignoring it,
>> but I wouldn't blame someone for including it either.
> I see it as more like ignoring short breaks in traffic dividers (like when
> crossing a divided highway).

Intersections have their own set of problems.  I'm referring here to
changes in the number of lanes which are not located within an

>> Nathan, what is one supposed to do if *all* lanes are turning lanes
>> (e.g. http://g.co/maps/4j2uh)?  Do we tag it lanes=0?
> I would use lanes=2 there, since that's how many through lanes there are
> before the turn lanes begin.

And you think any other number of lanes would be *wrong*?

I might lanes=2 here myself.  But I'd recognize that, in doing so, my
mapping was incomplete.

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