On 7/13/2012 11:56 PM, Peter Dobratz wrote:
I guess the main thing that is problematic about former railways is
their verifiability.
Between TIGER and GNIS and other imports, when I come across a road or
church that no longer exists (or in some cases never existed), I just
delete them. But before I delete the objects, I try to make some effort
to move them to their correct location where applicable. How am I
supposed to tell if these railways are in the right spot? In this
specific case, I was able to make an argument that the railway was in
the wrong spot and you managed to dig up a map that's more than 100
years old to help find the correct former railroad location.
Old USGS topos are a good source for most abandoned railways, and
they're now mostly online: http://nationalmap.gov/historical/ Even
modern topos (available in JOSM - "MSR Maps Topo" in the imagery
preferences) show many that are not obvious on aerials.
Where does the information about the geometry of these former railways
come from? What steps did you take to verify the data before putting it
in the OSM database? How are you going to document this information for
future mappers? It would seem to make sense to add additional
information to a source= or a note= tag indicating where the information
about the previous existence of the railway came from. Or maybe there
can be more verbose information added to the wiki somewhere.
Given that most roads added by mappers are at most tagged source=Yahoo
or Bing, despite these only being used for location and not name or
other characteristics, sourcing is not in practice a major concern for
most mappers. However, I understand the point about being difficult to
verify, and will try to provide better source tags where applicable.
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