[Talk-us] Semi-import of TIGER 2011 in a small area

Phil! Gold phil_g at pobox.com
Tue Jan 10 15:22:12 GMT 2012


I realized after doing this that I should probably solicit some feedback
on it.  While doing some ODbL readiness cleanup, I came across a
neighborhood (Clarksville, MD) where an anonymous user had added a bunch
of footpaths in 2007, but their editor appears to have effected changes to
TIGER-imported ways by deleting the original ways and adding new ones with
(presumably) the same nodes and tags.  That left me with nothing to roll
back to and no way to tell what had actually been changed, so I decided to
just replace the affected ways with a new TIGER import and then fix the
topology by hand.  While I was at it, I figured I'd use TIGER 2011 data.

Here's what I did:
* Download the 2011 TIGER/Line files for the surrounding county (Howard
  County).
* Run ogr2osm on the shapefile with the following parameters:
  * Add the following tags to every way:
    * tiger:mtfcc=<the line's MTFCC attribute>
    * tiger:linearid=<the line's LINEARID attribute>
    * tiger:source="TIGER 2011 ogr2osm import by asciiphil"
    * tiger:reviewed=no
  * If the line has a FULLNAME attribute, add the tag:
    * name=<the line's FULLNAME attribute>
  * Add additional tags based on the line's MTFCC attribute, with the
    following mapping:
    * S1100 => highway=motorway
    * S1200 => highway=primary
    * S1300 => highway=tertiary
    * S1400 => highway=residential
    * S1500 => highway=track
    * S1630 => highway=service, oneway=yes
    * S1640 => highway=service
    * S1710 => highway=footway
    * S1720 => highway=steps
    * S1730 => highway=service, service=alley
    * S1740 => highway=service, access=private
    * S1780 => highway=service, service=parking_aisle
    * S1820 => highway=cycleway
    * S1830 => highway=bridleway
* Open the resulting .osm file in JOSM and delete everything I didn't
  want.  This was accomplished by selecting all the roads I did want and
  then inverting the selection.  Also, the deletion took a really long
  time.  If I need to do this again, I'll probably use osmosis to cut out
  a bbox first and then just use JOSM to do the final paring.
* Upload the .osm file with JOSM.  This created a lot of duplication in
  the main database, but I wanted the first version of the ways to be
  pristine from import.
* Fix the data:
  * Download the entire area in JOSM.
  * Examine each duplicate way:
    * If there are tag edits by CT-accepting users, apply those edits to
      the TIGER 2011 way.
    * Delete the non-ODbL-clean way.
  * Ensure that all ways are connected appropriately to the rest of the
    road network.
* Upload the data fixes.
* Add ways as needed (in my case, the footpaths that the anonymous user
  had added; they're not in TIGER, but can easily be traced from aerial
  imagery).
* Upload the additions.

Are there any comments on my process or suggestions for things I should
have done differently?  (It's a small enough area that I can go back and
manually change things if needed.)

-- 
...computer contrarian of the first order... / http://aperiodic.net/phil/
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