If the position of the boundary is imported from a source that ultimately has a very high precision, for example Ordnance Survey or a Council's GIS system through a shapefile or similar, then the location as recorded in OSM will likely be more accurate than what would be obtained from tracing from aerial photos. In other words, if a boundary and a road/railway/etc *almost* coincide, more consideration should be given to moving the road to match the imported boundary than the other way around.
Having said that, the exact line of a boundary tends to get frozen at the moment the Order is made, even if the road/railway/etc is subsequently realigned. I strongly recommend that boundaries and other features do *not* get combined or even share nodes, unless it can be demonstrated that the link between them is dynamic, i.e. a change to one necessarily means a change to the other. > On 02/17/2022 3:41 PM David Davis via Talk-gb-london > <talk-gb-london@openstreetmap.org> wrote: > > > > Yeah Tom, > this is conclusion I reached too: > if a ward boundary is legally defined as being a particular geographical > feature (e.g. centre line of a road) then it is better to have that way on > OSM tagged with a relation (even if its position is a metre or two off > perfect) rather than have another line imported and tagged as the boundary. > And probably even worse: if the road *is* in precisely the right position, > neither is it helpful to have another imported line superimposed right on top > of it, as it makes it very fiddly to try and edit them subsequently. > So, slightly timeconsuming as it is, I think it's probably best to set them > up manually. > > On Thu, Feb 17, 2022 at 1:55 PM Tom Chance <t...@acrewoods.net > mailto:t...@acrewoods.net > wrote: > > > I've previously found it valuable to have the ward boundaries in OSM, and > > am responsible for all the Southwark (not Lambeth) ward boundaries, plus a > > few Lambeth, Croydon and Bromley. Sometimes the misalignment of open data > > and OSM data can lead to mistakes. It's not a big deal if they aren't in, > > but I don't see any reason to say they shouldn't be. > > > > If you're going to update them (great!) I think they work better as > > relations using - where relevant - existing objects like roads where they > > go down the middle of a road. Otherwise, again, things can get misaligned > > and otherwise go wrong. So a straight import isn't as good an option as the > > rather more painstaking manual approach. > > > > Tom > > > > m: 07866 447 075 > > w: http://tomchance.org/ > > > > > > On Wed, 16 Feb 2022 at 11:46, Russ Garrett <r...@garrett.co.uk > > mailto:r...@garrett.co.uk > wrote: > > > > > My controversial opinion is that these shouldn't be in OSM. > > > > > > The definitive boundaries are freely available as open data in OS > > > Boundary Line (although they won't usually appear there until after > > > the boundaries take effect). The current UK-wide coverage of ward > > > boundaries in OSM is pretty minimal, although it looks like most of > > > the old Lambeth wards are in OSM: > > > > > > http://overpass-turbo.eu/?q=W291dDpqc29uXVt0aW1lxIHEgzI1XTsKKAogIG53clsiYsSBbmRhcnkiPSJwb2xpxItjYWwixInEqMSqxKxpxK5sX2RpdmlzacSHxKYid8SjZMSxKHt7YsSfeH19KcSUxY8KxI8gxJ9kecSUPsSUxZNza2VsIHF0Ow&c=BJp6-ioHTL > > > > > > As someone who uses this boundary data relatively frequently, there's > > > no reason why I should use OSM when the data is incomplete, and > > > boundaries in OSM may have been altered (accidentally or otherwise). > > > They're not surveyable, the data is freely available elsewhere - I > > > don't see why it's worth spending our time making sure it's replicated > > > in OSM. > > > > > > Cheers, > > > > > > Russ > > > > > > On Wed, 16 Feb 2022 at 11:27, David Davis via Talk-gb-london > > > <talk-gb-london@openstreetmap.org mailto:talk-gb-london@openstreetmap.org > > > > wrote: > > > > > > > > Hello, > > > > a complete revamp of the electoral wards in Lambeth borough comes into > > > > effect in May 2022, with 25 new wards. > > > > (See > > > > https://love.lambeth.gov.uk/a-new-political-map-for-the-2022-lambeth-borough-council-elections/ > > > > for info). > > > > > > > > I'm guessing the boundaries are available as open data, > > > > and some bright spark on this list will know how to import it into OSM > > > > in a hugely more efficient way that me trying to manually draw and tag > > > > the new boundaries...? > > > > (Amusingly, on the map on Lambeth Council's page about it, someone > > > > literally has just drawn the boundaries by hand on top of a screengrab > > > > from OSM!) > > > > > > > > Anyone interested this task? > > > > > > > > (A few of the existing Lambeth wards were tagged on OSM already, but > > > > the majority actually weren't. But every existing ward boundary is > > > > changing in any case...) > > > > _______________________________________________ > > > > Talk-gb-london mailing list > > > > Talk-gb-london@openstreetmap.org mailto:Talk-gb-london@openstreetmap.org > > > > https://lists.openstreetmap.org/listinfo/talk-gb-london > > > > > > > > > > > > -- > > > Russ Garrett > > > r...@garrett.co.uk mailto:r...@garrett.co.uk > > > > > > _______________________________________________ > > > Talk-gb-london mailing list > > > Talk-gb-london@openstreetmap.org mailto:Talk-gb-london@openstreetmap.org > > > https://lists.openstreetmap.org/listinfo/talk-gb-london > > > > > > _______________________________________________ > Talk-gb-london mailing list > Talk-gb-london@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-gb-london >
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