[Talk-us] Duplicate Ways (or portions of ways)

Richard Welty rwelty at averillpark.net
Tue Jan 27 17:02:30 UTC 2015

On 1/27/15 11:33 AM, Dave Nesbitt wrote:
> Is there a standard way to identify and remove ways that are 
> duplicates (or portions which are duplicates)?  These are cases where 
> 2 ways use the same set of nodes (or similar common subsets of the 
> nodes) with very similar attribution.
i'm not sure there's a standard way. i cleaned up a bunch of similar stuff
in the NY 22 corridor a while back, it mostly is a result of multiple
mappers importing duplicative TIGER data back around 2007, followed
by one of the old de-dup bots cheerfully gluing the duplicated nodes
together. if i thought about it i might be able to come up with an overpass
query that would pull these out.

once i identify one, i usually unglue one of the shared nodes, select
one of the resulting 2, move it out so i can then select the way i
propose to delete, and delete it.

when cleaning up NY 22, i sometimes found dupe ways that didn't
have shared nodes. usually one of them was correctly connected
to the surrounding highway network and the other was not; then
it was important to identify the disconnected one and delete it
as there was a lot less cleanup work that way.

whenever you see these, it's important to look at the surrounding
area carefully for other problems. i have seen some very weird ones;
a chunk of I-787 in Albany had a way that wrapped back on itself.
that one had me mystified for a little while. it was tagged oneway
and had directional arrows pointing in both directions in JOSM.


rwelty at averillpark.net
  Averill Park Networking - GIS & IT Consulting
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