[Talk-GB] Ward Boundaries

Jerry Clough - OSM sk53_osm at yahoo.co.uk
Tue May 4 18:12:49 BST 2010


AFAIK ward boundaries have been done in two places:

Ipswich by Peter Miller pre OS data availability (e.g., http://www.openstreetmap.org/browse/relation/164654)
Broxtowe by will7777 in the last few weeks importing OS Boundary Line data. In the latter case data were imported and merged with existing OSM ways. I dont know how this was done, but I imagine it was a manual process. (e.g., http://www.openstreetmap.org/browse/relation/545299)

Both started with ways tagged as boundary=administrative admin_level=10, but I changed at least some of the Broxtowe ones to boundary=political as I know of at least some ward boundaries which are NOT contiguous with Civil Parish boundaries.

I would strongly advise using relations enabling ways which make up boundaries to be shared. This also obviates the old tag:left, tag:right procedure. Where ward boundaries make use of roads etc, we should replace any OS sourced way with the relevant way(s) from OSM. Having access to textual descriptions of the boundaries is of course really helpful. Equally many ward boundaries will need to make use of existing OSM boundary ways (Civil Parish, District etc), some of which may be of poor quality having been based on NPE as the best available non-copyright data source.

I would think a district is about the right size unit of work, any larger and merging with existing ways will be tedious, any smaller and the work will increase hugely with each additional boundary added. The 3000 US counties have not been sorted out at all yet, and I think there are more than 14000 civil parishes and easily 3000+ ward boundaries for GB. EdLoach (mainly), myself and others spent a lot of time sorting out some 200 odd boundaries in Haiti where a crude import was necessary to assist with geolocation of places in the countryside: it did teach us that starting with boundaries as individual polygons (whether drawn or imported) just makes for more work.

Advice from someone in the know as to how wards are regarded within councils may help in deciding the appropriate tagging.

Hope these notes are of some use.

Cheers,

Jerry




________________________________
From: James Rutter <jrrutter at gmail.com>
To: talk-gb at openstreetmap.org
Sent: Tue, 4 May, 2010 17:34:46
Subject: [Talk-GB] Ward Boundaries

...been tidying up the Surrey Heath district boundary now that we can do what we want with Boundaryline. Anyone got any advice for ward boundaries...can't find much at all on the wiki? What's the admin_level for ward or has it not been defined yet? What's the deal with the left and right tags I'm seeing...does this mean linework is 'handed' and if so how do we know which way round the lines are....does a tag like left:ward=Chobham do anything...will it render??

James


      
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