[OSM-talk] correcting/helping inexperienced mappers

[Nathan Edgars II]

Pieren wrote:
>I don't understand you. If they don't follow and don't cross, then you don't
>have duplicate nodes anyway...
The TIGER import has numerous topological errors, including many
highways crossing boundaries when they really don't (due to one or
both being in the wrong position). TIGER decided to put a node at each
of these crossings, and the import created them as dupes. More
recently a bunch of bots have gone through and automatically
eliminated these dupes.
The TIGER import also created highway-highway dupes at county lines.
These should be fixed.

As an example, here the township line follows the old border between
the provinces of East and West Jersey:
http://www.openstreetmap.org/?lat=40.29&lon=-74.67209&zoom=15&layers=B000FT
Roads were built along this boundary, since it formed a border between
land ownership and hence was an easy place to put a road.
In the 200+ years since, the roads have been widened, shifting the
centerlines away from the boundary, or even realigned in places.
The TIGER data had the boundary following the curves in Quakerbridge
Road where it crosses US 1, with a dupe node at every node on
Quakerbridge. Before fixing this, I had to undo the damage the bots
had done.

And don't get me started on boundaries created by annexing properties
one by one...here the edge is almost never the centerline of the road,
but the right-of-way line next to the road.