problems with Tiger road data

[Dylan Beaudette]

Hi everyone,

While I am quite familiar with some of the conventional problems with the 
TIGER road data, I am a little confused as to why a specific county in Ca is 
MUCH worse than other counties. Even adjacent counties have roads which are 
generally closer to reality...

The general trend is an offset of about 100 - 300 meters to the north-east, 
with the amount of distortion increasing to the east. 

Here is a link to an example of offset local roads in Stanislaus county, CA:
http://casoilresource.lawr.ucdavis.edu/ka-map/htdocs/?map=casoil&cps=-2055233,-21524,12000

the offset from the imagery is quite obvious.

Does anyone know what might cause this county to be so much worse than the 
others, and if there is some way I can fix the data? Right now it is stored 
in a PostGIS table, so applying some kind of translation would not be that 
difficult. 

Cheers,


-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341