I have done some preliminary measures of OSM coverage for Scotland and Wales based on using NUTS-3 regional boundaries as common ground to compare DfT figures for the length of roads in a local authority against the length of roads in OSM.
NUTS-3 is the basis for EU regional statistics, and they publish the boundaries as shapefiles. The precision isn't as great as you get from admin boundaries on OSM, but there are missing admin boundaries in Scotland and Wales, so this is a kind of stop-gap. On the whole the boundaries match up reasonably well, and where they don't exactly correspond, I can normally aggregate the road length statistics for a few authorities to get the figure for the equivalent NUTS region. It's only in the Scottish highlands where this doesn't work too well. Bascially the local authority for the Highlands crosses several NUTS regions, so I've had to take average figures to cope with boundaries that are not aligned. I realise the colouring could do with some work to make it more clear, but first version of the resulting map is here - http://www.reedhome.org.uk/Documents/OSMCover.png The headlines are that Anglesey and Edinburgh look well covered. Glasgow, Renfrewshire, Gwynedd are pretty good. While Powys, Aberdeenshire, Orkney and Shetland are looking a bit thin. For anyone interested in doing a similar exercise elsewhere in Europe, there are Eurostat figures for road lengths at the NUTS-2 level (i.e. the next largest geographical grouping after those I am using here). Eurostat only split "Motorways" and "Other Roads" so dealing with dual carriageways etc is going to be a bit iffy. However, I've done a quick comparison of their numbers for the UK, and the rough figures ((motorways * 2) + other roads) gives me a total that isn't a million miles away my more detailed calculations. The Eurostat figures are here - http://epp.eurostat.ec.europa.eu/portal/page/portal/region_cities/regional_s tatistics/data/database under "Regional Transport Statistics".
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