[Talk-us] understanding administrative boundary relations

[Ray Kiddy]

Hello -

I am on a quest to learn more about how administrative boundaries can
be managed as relations. I have a bit of experience with these
things, but I am discovering the limitations of my knowledge also.
Which was the point, actually.

I would like to be able to suggest that governmental entities could
manage their district geo data with OSM. I am interested in seeing why
this does not work now and what can be done. Well, and it would be
interesting to find out why so few cities in California actually seem
to have a relation. Or perhaps I am missing it.

I know that TIGER data was imported into OSM, but I am seeing some
disconnects. To be precise:

Using QGIS, I can load the vector files (SHP) from the following as two
different layers:

ftp://ftp2.census.gov/geo/tiger/TIGER2015/ELSD/tl_2015_06_elsd.zip
ftp://ftp2.census.gov/geo/tiger/TIGER2015/EDGES/tl_2015_06085_edges.zip

Using JOSM, I can see the "Sunnyvale East Channel":

https://www.openstreetmap.org/#map=19/37.364537971457935/-122.02110206207291

I cannot see how to get the id of this way from JOSM and its tag info
seems to be:

boat=no
intermittent=yes
name=Sunnyvale East Channel
scvwd:FACILITY=2026
scvwd:ROUTEID=20260
waterway=drain

And in QGIS, I can see the same feature (removing empty TIGER fields):

wkt_geom	LINESTRING
	-122.0213200000000171 37.36408999999999025
	-122.02097200000001465 37.36464099999999178
	-122.01992900000000475 37.36629399999999634
	-122.01963900000001217 37.36675400000000025
STATEFP	6
COUNTYFP	85
TLID	618169892
TFIDL	229597201
TFIDR	230278901
MTFCC	P0001
HYDROFLG	N
RAILFLG	N
ROADFLG	N
OLFFLG	N
EXTTYP	N
GCSEFLG	N
OFFSETL	N
OFFSETR	N
TNIDF	39083667
TNIDT	409312163

But there seems to be no connection between the feature in OSM and the
TIGER data. So, TIGER data was used to define new features? But perhaps
TIGER id data was not merged onto existing features?

I am certainly not seeing "tiger:tlid"="618169892" associated with this
object in OSM anywhere.

So, if I want to give the Sunnyvale District the relation that defines
its boundaries, I cannot use TIGER data to find those lines? Or rather,
I must use the TIGER data and find the line in OSM and set up the
connection myself?

Ok.... Any other suggestions?

thanx - ray


ps:

My early stumblings are in my diary:

http://www.openstreetmap.org/user/rayKiddy/diary

Please excuse any ignorance on my part. I know a bit about the GIS
practices of the state of California. I have a very small bit of
experience with Santa Clara County. I have a smidgen of knowledge about
the city of Sunnyvale. And I have more exposure to the Sunnyvale
Elementary School District, having once been on the Board. And I
develop database software and am interested in mapping applications.