[OSM-talk-ie] When is a townland a townland (and when is it 2+ townlands)?

[Rory McCann]

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Hi all,

A while ago I mentioned a possible problem with the Logainm data
import, where 2+ townlands were getting the same logainm reference[1].
Upon closer investigation, I don't think this is a bug with the import
process, but a question of "Is a townland is one townland or many
townlands?".

Consider Graiguealug townland in Carlow. It's in OSM as 3 different
townlands: OSM ids https://www.openstreetmap.org/relation/2196774
https://www.openstreetmap.org/relation/2274862
https://www.openstreetmap.org/relation/2274863 all touching each
other. Each is in a different civil parish[2].

However Logainm only has one entry http://www.logainm.ie/en/3531 which
is in 3 different civil parishes. Logainm allows one townland to be in
more than one CP. If you look at the GSGS map, only one townland is
shown on the map, and the total area (~400 acres) is similar to the
total off the 3 townlands in OSM.

It looks like one townlands was split into 3 townlands so that each
townland would be in one and only one CP.

However I don't think this is the right approach. I think the OSM
philosophy of "One Feature, One OSM Element"[3] should apply, and that
those 3 townlands should be merged into 1. The CP boundaries should
physically stay where they are, but they will not line up with a
townland boundary. I seen other examples of townlands crossing CP
boundaries and have mapped them as one townland, with a CP border
going through the middle.

I'm tempted to merge townlands like this into one townland. What do
people think?

Rory

[1]
https://lists.openstreetmap.org/pipermail/talk-ie/2016-March/001499.html
[2] Townlands.ie:
https://www.townlands.ie/carlow/forth/templepeter/templepeter/graiguealug/
https://www.townlands.ie/carlow/forth/tullowmagimma/templepeter/graiguealug/
https://www.townlands.ie/carlow/forth/nurney/templepeter/graiguealug/
[3] https://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element
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