I've just posted an updated map of UK coverage at http://www.reedhome.org.uk/Documents/OSMCover.png
There are a number of significant changes in this version: a) As I half suspected, there was an error in the way I was handling map projections in the previous version. This resulted in overstating the length of roads on OSM. I think I've now fixed this, and it seems to give more plausible results b) We now have sensible looking boundaries for all the English higher level councils (Counties, Met boroughs, London & Unitaries) c) In theory, all the counties should now cover the admin boundary, not the ceremonial area. I've done some quick checks, and so far they've been OK - though Buckinghamshire looks suspicious. Previously some unitary authorities were counted twice, and pushed up the county figures Buckinghamshire currently shows 117% of roads mapped. I suspect this is something I'm doing wrong, or something wrong with the boundary, but haven't yet worked out what is going on. Similarly Barking and Lambeth could be too high to be true. Matching the road lengths to the current boundary of Cheshire and Bedfordshire is a bit of a kludge because of the recent boundary changes. There are better ways to handle these ,but for now they are rough approximations. OSM doesn't yet have decent boundaries plotted in Scotland and the parts of Wales. I think I've figures out a way to use boundaries from the EU NUTS3 regions for an initial estimate. Most of these match local authority boundaries, so I should be able to estimate coverage in a similar way for most of them - I have the data, but I've not processed it yet. Bearing in mind that these are initial results, with plenty of scope for errors, and not much checking yet...... The lowest levels of coverage seem to be in : North-East Lincs (24%) Oldham (28%) Tameside (32%) Luton (35%) S. Tyneside (37%) Sunderland (38%) Bolton (38%) Barnsley (39%) The highest levels of coverage (apart from Bucks, which I suspect is faulty) are in: Barking & Dagenham Lambeth Greenwich Isle of Wight Bexley Kingston on Thames Bromley Birmingham Reading Portsmouth Southwark City of London Kensington & Chelsea (all of these come out just above 100%) Luton (at 35%) and Bracknell (at 61%) stand out as the lowest coverage in the South-East. I'll upload more detailed figures later. Thanks for all the comments so far.
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