[OSM-talk] razed railways and other things that don't exist today

[Mateusz Konieczny]

Which OSM Wiki pages you checked to find out
reason for existence of things like demolished:building=yes?

Recently demolished building may be visible on aerial images

Using lifecycle prefixes it is possible to clearly mark that specific object must not be
remapped without proper verification.

Once there is no real risk of remapping them by person thinking that this objects
are still existing such elements should be deleted from OSM.

Fully gone elements (for example levelled railway embankment replaced by
residential buildings) should be deleted from OSM.

Is there any OSM Wiki page claiming otherwise?

> it is used by Open Railway Maps (ORM)

If they want to display also fully gone railway tracks -
then they need to use OpenHistoricalMap dataset

If they use OSM then they will show only recently
demolished one and ones that left traces.

Some incorrectly mapped ones may be displayed,
but they may be correctly deleted at any moment
once this mistakes are spotted.

-------------------------------------------------

Note that when you found some gone railway
mapped in OSM then it is useful

- edit OSM object to note which traces are left if any
(ideally, it would be done by original mapper)

- or delete nonexistent sections without traces
and review edits that added them.
It is common to see changeset adding
400km of destroyed railway without any verification
in place, in such case entire changeset should be
reverted.
Obviously in case of any doubt - comment using
changeset comment and create OSM note,
then get back to it in some time
( https://www.openstreetmap.org/note/3412415
is my latest one, spotted it while mapping something else)

Without doing this mappers of railways gone without
any trace will easily win. They copy from old
maps and can easily mark hundreds of kilometers
in one edit.
Sometimes they demand to prove nonexistence
of railways.
But it is fine to remove entire edit if it was done
without survey and added features not
existing in any way on the ground.

Oct 25, 2022, 09:42 by 61sundowner at gmail.com:

> Hi,
>
> Question:
>
> If OSM is about mapping what exists today .. why have the tags that mean there is nothing left of it?
>
>
> demolished:*=*
>     Not existing anymore because of active removal
>  removed:*=*
>     Not existing anymore because of active removal (possible duplicate of demolished:*=*)
> razed:*=*
>     Not existing anymore because of active removal (duplicate of removed:*=*, possible duplicate of demolished:*=*)
> destroyed:*=*
>    Destroyed by an event other than active demolition
>
> I think these tags would be of use in Open Historic Map (OHM) and that is possibly why they are in the OSM wiki?
>
> Possibly the OSM wiki should recommend that the data with these tags be moved to OHM?
>
>
> The argument for mapping these things from the 'old railway' people is that;
>
> 1) it does not render on the 'standard map' so it is not a problem.
>
> 2) it is used by Open Railway Maps (ORM)
>
>
> My contention is;
>
> 1a) This is a problem when people try to map new things, the old things lead to mapping things that never existed like railway=crossing where a new footway/highway is also mapped over a now non existent railway line.
>
> 1b) People mapping new things may not see the old stuff on the new imagery .. and simply delete it, leading to edit wars.
>
> 1c) People map things like an old embankment for old railway lines .. right through existing roads
>
> 3) Old data should be mapped into OHM so it can be preserved .. together with the start and stop dates .. these 2 tags are fairly well ignored in OSM.
>
> 2) ORM should take current data from OSM and old data from OHM. This would add the start/end dates that could be used in ORM to select the time period. Thus those only interested in the present could have that, and those interested in some past date could have that.
>
>
>
>
> _______________________________________________
> talk mailing list
> talk at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20221026/d7cad527/attachment-0001.htm>