[OSM-dev] Ways containing same nodes

[Matthias Julius]

Anton Popov <apopov at cloudmade.com> writes:

> Hello everybody,
>
> I've found two ways in Germany, that has same nodes:
> http://www.openstreetmap.org/browse/way/23735657
> http://www.openstreetmap.org/browse/way/23735661
>
> I've examined the history & it seems that following changeset caused a
> problem:
> http://www.openstreetmap.org/browse/changeset/259367
>
> The main questions are How this could happen? and How to correct these ways?

There are many possibilities: A bug in the uploading software, the
user somehow duplicating the way, the user not saving his data after
uploading, or - most likely - an aborted HTTP connection after the
server received the data (either by the user hitting cancel or by a
broken network connection).  The latter prevents the client from
learning the IDs the server has assigned to new objects and on next
upload it will re-upload the same objects again as new.

>
> As far as I can see correct way is 23735661 - the only missing tag is
> "maxspeed" - am I right?

If the ways really have the same nodes one can do Combine Ways (C) in
JOSM and JOSM will merge all tags onto one way.  If they don't exactly
overlap one can in JOSM select them both and all tags of both ways
will be listed in the properties list with the tags that have
different values displaying <different>.  Then one can edit those tags
and the values that are actually used by one of the selected ways are
shown in bold in the value drop-down.  Once all tag values are merged
one can delete one way.

Matthias