[Talk-GB] Estimating coverage

[Peter Miller]

On 19 Jul 2009, at 11:54, Chris Hill wrote:

> Peter Reed wrote:
>>
>> Of the authorities I have managed to measure, the following all  
>> show more road mapped than the DfT believes exists:
>>
> Having mapped every road in Hull (Kingston-upon-Hull since today is  
> a Sunday), some are fairly new and may not appear on the DfT  
> figures.  How did you account for dual carriageways?  If you counted  
> both carriageways and DfT only counted the road once that might  
> account for some the difference.  Some of the dual carriageways in  
> Hull use the dual_carriageway relation, though not all - I confess  
> that I gave up adding it when it seemed to be completely unused.

Firstly can I say thank you Peter! This is a great example of how OSM  
progresses with people popping up with new ideas and innovations where  
the first you hear of it is when the person has done it. I agree that  
dual carriageways are a potential source of over-counting. non-adopted  
roads might be another. Are you clipping roads at the boundary yet? If  
not there you may be including road sections that are only partly in  
the county.

With regard to dual-carriageway relations, I think it is only a matter  
of time before they are taken up and then there will be a rush to add  
more as with the cycle routes and OpenCycleMap. I have added relations  
for dual-carriageways in my area as well.

Could you publish a table of authority boundaries in the UK, their  
name, their admin-level and if you consider them to be complete or  
not? There are various manual boundary checks but none of them seem to  
work all the time and some say things are ok when other ones don't. We  
still don't understand why Hampshire is not recognised by Geofabrik  
boundaries viewer for example.

I added some more boundaries to the England page today (ie some more I  
found on the map rather than ones that I added).
http://wiki.openstreetmap.org/wiki/WikiProject_England

Btw,  are people ok if I go through the existing ceremonial boundaries  
(the ones that are only ceremonial and not administrative) and change  
there tagging to boundary-ceremonial (rather than  
boundary=administrative)?

A final point. How does one create relations containing relations?  
There is a relation for 'London Boroughs'. I wondered if we should  
produced one for 'Regions of England', and 'ceremonial counties of  
England' and add the appropriate relations to them.

Here is the 'London Boroughs' relation as an example. I like the map  
that is produced from it.
http://www.openstreetmap.org/browse/relation/51908



Regards,



Peter


>
> Cheers, Chris
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