[Tagging] noexit=yes on ways ?

Marc Gemis marc.gemis at gmail.com
Tue Apr 8 16:48:54 UTC 2014


now make sure that all QA-tools and editors/validators follow those rules.
I fear that otherwise we will keep seeing noexit tags that are used
incorrectly.


On Tue, Apr 8, 2014 at 6:38 PM, André Pirard <A.Pirard.Papou at gmail.com>wrote:

>  Hi,
>
> A problem raised in 2013-12 on talk-be regarding the error with sign F45<http://wiki.openstreetmap.org/wiki/Road_signs_in_Belgium#F45>that nobody corrected.
> I finally did it.
> I had brought the subject to Tagging and it reached a consensus with
> Georg's message which I quote below.  But nobody changed the wiki
> accordingly, which I just finally did too.
>
>    1. noexit cannot be used on ways because that does not show what end
>    "cannot pass"
>     2. noexit is unsuitable for full routing because it does not apply to
>    a particular means of transport (unlike a hypothetic bicycle=noexit)
>    3. a noexit like tag is unnecessary for routing; routing has got all
>    it takes
>    4. noexit is used to draw the attention of sanity checks on the
>    validity of the tagging
>    5. it could also highlight the no-passing condition when it's barely
>    visible on the map, but if it were rendered
>     6. there is no need to tag each and every "noexit"; we're not
>    dressing a Xmas tree.
>
> The wiki should be carefully looked after indeed.
>
> Cheers,
>
>   André.
> On 2013-12-03 15:41, Georg Feddern wrote :
>
> Am 03.12.2013 14:48, schrieb André Pirard:
>
>
>
> I agree to:
> This tag is
> - not necessary for routing
> - senseless on ways
> - only useful on nodes (the last one, where no other way is connected)
>
> The wiki should be changed, especially the use on ways should be removed.
>
>
> But I do not agree to
>
>
> I doubt very much that this tags helps anybody or any quality-check
> program to understand anything. A note should suffice, and I think the best
> option would be to remove that confusing tag.
>
>
> It is useful for quality-check programs to determine "This is not a
> missing connection to nearby ways". (false positives)
> A note would have to be clear and machine-readable for this case.
>
> It might be useful for renderers as on a map it might look as a connection
> (because of oversize of rendered ways).
> But this could be determined by preprocessing also.
>
> Georg
>
>
>
> On 2014-04-08 13:33, Marc Gemis wrote :
>
> I tagged noexit=yes on the ways.
>
> Why ? If I remember correctly some more experienced mapper told me it was
> ok to do so.
> And perhaps I read the wiki page before June 28, 2011, when there was
> nothing mentioned about way or node.
>
>   You cannot assume each mapper reads all wiki pages every week or follow
> the tagging mailing list to keep up-to-date with the changing definitions
> of tags.
>
>  Another reason is that, as Pieren pointed out, many features are mapped
> on the way, not on a single point.
> And yet another reason is that the OSM definition is different from the
> traffic code definition, where noexit is placed on each street where cars
> cannot leave the street via another exit.
> So people might just tag it without reading the wiki at all.
>
>  The tag info on the wiki page shows enough usages on ways to make it a
> viable tagging method.
>
>  Enough reasons why people might tag this incorrectly according to the
> current wiki definition ? :-)
>
>
>  regards
>
>  m
>
>
> On Tue, Apr 8, 2014 at 12:57 PM, fly <lowflight66 at googlemail.com> wrote:
>
>> On 08.04.2014 12:10, Pieren wrote:
>> > On Sun, Apr 6, 2014 at 3:48 AM, fly <lowflight66 at googlemail.com> wrote:
>>
>> >> noexit=yes has nothing in common with the traffic_sign as:
>> >>
>> >> 1. it only is about motorized traffic where noexit=yes is about every
>> >> travel mode.
>> >> 2. it is used at the beginning of a cul-de-sac and an information for
>> >> driver of motorized vehicles where noexit=yes is always tagged on the
>> >> end node of a way without any connection and is a hint for mappers and
>> >> QA tools.
>> >>
>> >> Please, do not mix it up.
>> >
>> > Please, return to earth. Tagging traffic signs is just a funny
>> > activity in fully mapped areas. How do you specify a speed limit in
>> > OSM ? with a "traffic_sign" tag on a node or primarily with the
>> > "maxspeed" on the way ? I could repeat the same question for many
>> > other features.
>>
>>  Do not know if you speak german, but one person did tell us that she/he
>> is mapping the traffic_signs as addition one the ways on talk-de at osm [1].
>>
>> > I'm still waiting some clear explanation about the difference of a
>> > "noexit" and a "cul-de-sac".
>>
>>  You find quite some differences, if you read the mails carefully.
>>
>> The major points in my view are:
>> * We do not need to tag cul-de-sac as defined by the traffic_sign. This
>> information is available through geometry and/or access tags.
>> * The traffic_sign is always about motorized vehicles but we map for all
>> traffic modes. noexit=yes is wrong as soon as there is any connected
>> highway.
>>
>> One way to manifest the difference is to only tag it on nodes and not on
>> ways.
>>
>> > Once you understand there is no
>> > difference, you understand why 40% of the noexit tags are on ways ....
>> > When you have this huge gap between the wiki definition limiting the
>> > tag on the last node and the real contributors behaviour, you should
>> > ask if the wiki makes sense but not blaim the contributors.
>>
>>  No one did blame anyone. I only tried to find the reasons for this
>> misunderstanding and one was definitely the wiki page which is still not
>> perfect but did get some updates the last days. Some other pages where
>> updated, too.
>>
>> > Note that for QA tools, the tag on the last node or on the way itself
>> > are both technically easy to support.
>>
>>  Sure, but overall it makes it more difficult and how should this work
>> with splitting ways ? Could you please point me to one editor which
>> properly works with splitting a way tagged with noexit=yes or don't you
>> think that it is wrong that after the split both parts are tagged with it
>> ?
>>
>> We could simply deprecate noexit=* and replace it with note=noexit but I
>> am not sure if this solves our problem and tools need to support strings
>> and multivalues as noexit might not be the only word of the note=* tag.
>>
>>
>> fly
>>
>> [1]
>> https://lists.openstreetmap.org/pipermail/talk-de/2014-April/107967.html
>>
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