[OSM-dev] WG: Merkaartor creates invalid highway tags like highway=unclassified; track

Gerd Petermann GPetermann_muenchen at hotmail.com
Tue Mar 15 09:37:40 UTC 2016

I just noticed that I accidentially replied to Andy instead of the list, see below...


Von: Gerd Petermann
Gesendet: Dienstag, 15. März 2016 06:38
An: Andy Townsend
Betreff: AW: [OSM-dev] Merkaartor creates invalid highway tags like highway=unclassified; track

Hi Andy,

okay, I think I got your point reg. "corrections", and for sure I did not want to say that my time is more valuable than yours.

Maybe I was a bit agitated when I wrote this.

reg. the ediors: As I wrote before I don't know what one has to do to create the invalid tags,

my concern is that it is too easy to do without intention. If that is true it should be fixed in the editor.


Von: Andy Townsend <ajt1047 at gmail.com>
Gesendet: Montag, 14. März 2016 23:57
An: dev at openstreetmap.org
Betreff: Re: [OSM-dev] Merkaartor creates invalid highway tags like highway=unclassified; track

On 14/03/2016 08:58, Gerd Petermann wrote:

Hi all,

I hoped that this problem was solved whe iD was corrected, but

some less often used editors still allow to create these erroneous tags.

Since iD was corrected the only changesets with these errors are created

by Merkaartor  and Potlatch 2. Fortunately these editors are rather rarely used.

I hope the programmers of these editors are also working on a fix ?

I think perhaps that we need to to a step back here.  You seem to be equating "valid" data with "correct" data, when in reality if something is "invalid" it's usually a very good indication that further survey is required, and if it's been made "valid" by someone picking a key/value combination that "the original user might have meant", there's no guarantee it's correct.

For example, on https://www.openstreetmap.org/node/1057585745/history you've changed the obviously invalid "footway=sigtnpost" to "information=guidepost; tourism=information".

OpenStreetMap | Node History: 1057585745<https://www.openstreetmap.org/node/1057585745/history>
OpenStreetMap is a map of the world, created by people like you and free to use under an open license.

What you've changed it to is "valid", but not necessarily correct; it might instead be an "information=route_marker", or it might be a bridleway marker suggesting that one or both of https://www.openstreetmap.org/way/5037727 and https://www.openstreetmap.org/way/167425506 should actually be "designation=public_bridleway" and have "foot=yes", "horse=yes" and perhaps "bicycle=yes" tags on them.

Now that you've "fixed" the data there there's no longer something that's "obviously invalid" that people can see and say "I wonder what that is supposed to be" before going out and surveying it.  Also, it's perhaps worth mentioning in passing that telling me via https://www.openstreetmap.org/changeset/35996416 to "Please contact the original mapper" has perhaps lost some politeness in the German to English translation (as I'm sure it would the other way if I'd tried to write it in German); it suggests that your time is far more valuable than other mappers'.

It's a similar issue with semicolon-separated values.  If someone has created (say) "sidewalk=both;right" then it's pretty easy to see what's happened - someone has merged two ways together and not known to check all the tags. However, imagine if instead of "sidewalk=both" or "sidewalk=right" one of the ways hadn't got a sidewalk tag on it at all.  The result would still be incorrect, but there's no way to easily detect it.  The only way to prevent this problem occurring is to educate mappers about tags that they might not be aware of, and the best way to do that is to actually talk to them, not to suggest $technical_fix to whatever editing software they happen to be using.  Editors can help, sure (for example, the way that Potlatch 2 highlights semicolon-separated values is one way of dealing with it) but ultimately a human needs to answer the question "why did that just happen" in order to prevent new and not-so-new mappers making the same mistake again.

Best Regards,

Andy (SomeoneElse)

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