Learon Dalby gave a talk at US State of the Map regarding road centerline
data. For slides of the presentation, see
http://www.slideshare.net/learondalby/open-the-data
My summary is that he has gathered each county's GIS data over a period of
time and now has the entire state's data with a license (PD?) that allows
importing into OSM. I haven't looked in detail at the Arkansas TIGER data,
but it was likely gathered before all roads had been assigned names.
Possibly the TIGER geometry is not as good as the current data from the
counties. The proposal is
1.) Use the GIS road centerline data to replace untouched TIGER data in
OSM across the state of Arkansas.
2.) Establish a system to allow updates to the multiple databases over
time - not necessarily an automated 'sync operation', but a bidirectional
feed of changes. OSM changes within an area would be fed back to the state
GIS, then on to the county GIS where they would decide to use it if
applicable. County changes would propagate back to OSM in the form of
some type of change set that someone could review and apply to OSM data if
applicable. In OSM terms, this would include the edits that break a way
into many smaller ways for bridges, speed limits, lane counts, traffic
lights, surface, sidewalk attributes, public transportation routes, etc.
In the possibly similar case of Massachusetts, I cannot tell from the wiki
whether they used the state centerlines instead of TIGER, or if they had
replaced TIGER with MASSGIS data.
It is of utmost importance to preserve any roadways touched by a human
mapper. In AR, these roads consist of mostly Interstates and US highways
that have been fixed up for proper routing and relations. To a lesser
extent, some edits are from the attack of the duplicate node bots near
county borders. I did a study for the state of Arkansas to determine how
many roads have been touched so far:
https://spreadsheets.google.com/ccc?key=0AtqECyNeMFlGdF9PTl8yR1dVdzJUZERyMEZtcG5sT0E&hl=en
For purposes of this study, I have treated the Un-abbreviation bot edits
as unedited, if version=2. The Un-abbreviation bot can be run again later
if necessary, or applied to the incoming AR GIS data before importing it.
Note that there are 3 worksheet tabs on the bottom of the spreadsheet.
There is one active mapper in the city of Little Rock; he has touched many
roads as he has improved the map in that area. Carl Anderson gave an
excellent talk on their experience in importing county GIS data in some of
the Atlanta region. Based on his experience, it is unlikely that the
entire process can be automated. It will be some form of manually deleting
the unedited TIGER ways, then stitching the AR GIS data to any existing
edited roads. Most roads have not been touched, so remote, unedited
counties would import with less labor. Any techniques used here could be
applied to other states with PD road centerline data.
This is the limit of my knowledge - I have no experience with the tools
Carl mentioned that can assist with importing data into an existing system,
and I haven't looked at the AR GIS data to see what other challenges may lie
ahead. So I'm passing the ball to the next data import enthusiast...
_______________________________________________
Talk-us mailing list
Talk-us@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-us
