[Tagging] noexit=yes on ways ?

André Pirard A.Pirard.Papou at gmail.com
Tue Apr 8 16:38:08 UTC 2014


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
 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.



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
> <mailto: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
>     <mailto: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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