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<p class=MsoNormal>There is more sophisticated analysis of OSM coverage using OS
vector data (<a
href="http://povesham.wordpress.com/2010/04/04/openstreetmap-completeness-evaluation-march-2010/">http://povesham.wordpress.com/2010/04/04/openstreetmap-completeness-evaluation-march-2010/</a>
), but for what it’s worth, I have produced another simple comparison between
DfT statistics and the length of roads plotted on OSM.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>My previous attempts used OSM boundary data to isolate each
local authority, but this one uses OS boundary data for each local authority in
Great Britain. Boundaries for Northern Ireland are not included in the OS data
as far as I can see, so they do not appear.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Within each authority I measure the length of roads of each
type, then compare them to the statistics published by the Department for
Transport. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The results are here - <a
href="http://www.reedhome.org.uk/Documents/OSMCoverOSApr2010.png">http://www.reedhome.org.uk/Documents/OSMCoverOSApr2010.png</a>
for the image, and the data is here - <a
href="http://www.reedhome.org.uk/Documents/OSMCoverOSApr2010.csv">http://www.reedhome.org.uk/Documents/OSMCoverOSApr2010.csv</a>
<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The eagle-eyed might notice that I have simplified the
boundaries to speed plotting of the image, but the original calculations were
done on the full OS boundary detail. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The results differ slightly from my previous attempts at doing
this using OSM boundary data. Partly this will be due to the new boundaries,
but I have also been more stringent in classifying roads that have ambiguous
tags.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>With ward boundaries now available from OSM, I’m hoping
that I can now take some of this to a more detailed level<o:p></o:p></p>
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