[Talk-us] TIGER 2017 Pennsylvania county line import?

Albert Pundt roadsguy99 at gmail.com
Wed Jan 24 01:29:12 UTC 2018


> > I noticed many of the county lines in Pennsylvania are off by quite a
> > bit. I took the county lines from TIGER 2017 and imported them into
> > JOSM, and am ready to begin switching out the existing county lines

> Do you mean you'll keep the relations intact and just replace the member
> ways, or do you intend to delete the relations wholesale and introduce
> new ones?

> Where county boundaries are shared "upwards" by the state boundary, or
> "downwards" by a city boundary, will you ensure that these links are
> kept? County boundaries often don't exist in a vacuum and hence when the
> county bondary changes, the city/state boundaries need to change too,
> else you'll end up with cities straddling a county border or counties
> straddling a state border...

> Depending on what exactly you're planning to do, the JOSM "utilsplugin2"
> function "replace geometry" might be useful; it would try to keep the
> existing objects in OSM and just refine their geometry, rather than
> deleting and re-creating stuff.

I certainly don't intend to delete and recreate any relations for no
reason. Links with other boundary types will of course also be kept. The
state boundary itself will likely be redone as well to match the more
accurate newer TIGER data, though along the Mason-Dixon Line the border is
defined by boundary stones which are already mapped, so I won't touch that
part.

I'll definitely take a look at that plugin, it could help quite a bit. I
also know not to delete member ways either in order to preserve history.
What I've been doing as I edit roads is reduce the original way to a short
segment, merge that in with the new way, and then just delete the last node
to fully roll the old history in with the new way. If that plugin removes
the need to do this for every single boundary way, that's great!

—Albert

On Tue, Jan 23, 2018 at 7:31 PM, Frederik Ramm <frederik at remote.org> wrote:

> Hi,
>
> On 01/24/2018 12:46 AM, Albert Pundt wrote:
> > I noticed many of the county lines in Pennsylvania are off by quite a
> > bit. I took the county lines from TIGER 2017 and imported them into
> > JOSM, and am ready to begin switching out the existing county lines
>
> Do you mean you'll keep the relations intact and just replace the member
> ways, or do you intend to delete the relations wholesale and introduce
> new ones?
>
> Where county boundaries are shared "upwards" by the state boundary, or
> "downwards" by a city boundary, will you ensure that these links are
> kept? County boundaries often don't exist in a vacuum and hence when the
> county bondary changes, the city/state boundaries need to change too,
> else you'll end up with cities straddling a county border or counties
> straddling a state border...
>
> Depending on what exactly you're planning to do, the JOSM "utilsplugin2"
> function "replace geometry" might be useful; it would try to keep the
> existing objects in OSM and just refine their geometry, rather than
> deleting and re-creating stuff.
>
> Bye
> Frederik
>
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
>
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