London Boroughs Challenge

[Edgemaster]

I'll also start by thanking Edgemaster for that fabulous map, I've spent most of the afternoon looking at it try to gleam information from it! It was also most interesting to looking at where our route went well or poorly according to that map, but I'm not telling you my findings! I knew you were into digital mapping from looking at your website, but I must say the map is highly impressive and quite clever to be able to pick up where the boundaries are listed on all those scales of OS maps. However Edgemaster I profess that your last sentence in that post made no sense at all to me!

(As may happen in a certain quiz that's full of such terms you've never heard of, Paxman would say: "Starters for ten, Define monkey-patching.")

When code is written on top of existing code in a way such that it doesn't impact upon the original code's functionality. However, in this case it has produced unexpected side-effects. At least, that's how I interpret that term.

Anyhow I'm also going to back up my team mate in saying that Bexley the Borough is worse than Vauxhall the station, at least Vauxhall has many a train North to Waterloo, unlike the three lines through the Borough. But Hassan, you don't have to go through Greenwich, there are a few non Greenwich alternatives, but I agree that non are realistic of they involve doubling back.

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However your map has posed me a question Mr Edgemaster. Namely the "canonical" status of Dr John's original map, and whether it should be the accepted rulebook for the challenge for ever more as well as the issue of stations which straddle more than one Borough.

Here's the orignal quote:

My view on this is as follows ...

(1) Where a station (consisting of all station buildings, track passing through the station and entrances and exits) straddles two or more Boroughs, one shall be allowed to count the stop there as visiting either (any) one of the Boroughs, but one must separately visit the other Borough(s).

So one may choose to count a stop at New Southgate (if we agree that it indeed straddles Barnet and Enfield) as a visit to Barnet, but must then visit Enfield separately. Alternatively, one may choose to count the same stop at New Southgate as a visit to Enfield, but must then visit Barnet separately. One may only count one Borough per station, unless one pays a repeat visit to it.

I would propose to apply three other rules to this challenge.

(2) The map (referred to elsewhere in this thread) should be considered canonical to the extent that any station stop shall count as acceptable if it is shown as part of the relevant Borough on the map. However, one may also count a station as part of a Borough, even if not indicated on the map, if one can authoritatively demonstrate that the map is in error or incomplete. One may only record a visit to one Borough per station.

The map (I don't know its original source) looks like a labour of many hours, but is a little out of date and may contain a handful of errors. Ideally, it should be updated.

If this isn't too difficult, too technically challenging, or a administrative nightmare, would it be feasible for your map Edgemaster to update vis a vis boundary changes? I only ask as it is highly likely that boundaries will change at some point in the future either thanks to a re-organisation of local government or due to physical changes on the ground. While some changes may be minimal, it is also possible for these to effect the challenge, as James the Gill has highlighted! If this was adopted the record could change as different configurations arise, much the same as when the GWR has to change when the number of stations changes. The map could then update itself, or a new version could replace it, say 2009 Version 2, if it was needed this year.

Any views from interested parties on this point would be greatly appreciated, as I think we need to set up something for the rules to reflect future changes before they actually happen, if they happen at all, or have already happened since the Dr John map!

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The data on my map is direct from the Ordnance Survey, so I'd assume they'd keep it up-to-date.

It is theoretically possible for the boundaries to change, but realistically it happens very infrequently and usually just to reunite a plot of land so it lies completely within one borough. A list of all the boundary changes since the Greater London boroughs were formed can be found on wikipedia (and for all those who don't like wikipedia, that particular article has the majority of its sources (ie, the Statutory Instruments issued by government) listed as references).

On the issue of straddling stations, tubeguru's post had stuck in my head:

The boundary between Hammersmith & Fulham (the borough I live in) and Kensington & Chelsea does indeed run along the line of the railway through Olympia station. The northbound platform is accessed from Olympia Way, a road that belongs to H&F. The entrance via a footbridge to the southbound platform is via Russell Road, which is a road residing in K&C.

So yes, passing through Olympia station once will only count as a visit to the borough on the same side as the platform you stop at. If your train is for some reason told not to call at Olympia and is routed through the middle road, then you will have visitied neither borough at that location!

And I'd completely forgotten about John's rules, so my reason for creating the map - to see which platforms are in which borough is a moot point.

And on the point of the tube map with boundaries, I'm currently working with scrxisi to help him with his beautiful re-make.

[jbom1]

However your map has posed me a question Mr Edgemaster. Namely the "canonical" status of Dr John's original map, and whether it should be the accepted rulebook for the challenge for ever more as well as the issue of stations which straddle more than one Borough.

Obviously the re-make will become the official map once it's completed and has been suitably checked over. I intended "canonical" in the sense of "official", "recognised" and "authoritative", rather than "eternal" (and the map is not in any sense mine).

Edgemaster's beautiful map demonstrates that we need not just to know the boundaries but also accurate locations of the stations. In the case of Manor House, the map correctly shows the station building in Haringey; the case for its being in Hackney is based on several other subway-type entrances to the station (not on map?) being located in Hackney.

[Edgemaster]

However your map has posed me a question Mr Edgemaster. Namely the "canonical" status of Dr John's original map, and whether it should be the accepted rulebook for the challenge for ever more as well as the issue of stations which straddle more than one Borough.

Obviously the re-make will become the official map once it's completed and has been suitably checked over. I intended "canonical" in the sense of "official", "recognised" and "authoritative", rather than "eternal" (and the map is not in any sense mine).

Edgemaster's beautiful map demonstrates that we need not just to know the boundaries but also accurate locations of the stations. In the case of Manor House, the map correctly shows the station building in Haringey; the case for its being in Hackney is based on several other subway-type entrances to the station (not on map?) being located in Hackney.

My map isn't so beautiful, its just useful. That is the one issue with the OS' street-level of detail, its very hit and miss with LUL stations, sometimes it outlines them as a public building, other times it doesn't. The problem with Manor House is that it's mainly underground, there's no way of telling which bits are where.
Using my map, all of the subway entrances on the corners are in Hackney, the surface subway entrance building is itself straddling the border between the two (according to the OS map, the building either isn't plotted, or is in the wrong place and of the wrong length)

I'm guessing the ticket office is under the road junction?

[jbom1]

Wow, impressive detail! Where did you get the locations of all the subways from?

[Edgemaster]

Close examination of Google StreetView, then plotting on the map.

[greatkingrat]

I think Manor House should be considered as on the boundary of Haringey and Hackney and able to counted for either borough (but not both).

[jbom1]

I think Manor House should be considered as on the boundary of Haringey and Hackney and able to counted for either borough (but not both).

Agreed.

[jbom1]

Does anyone know how accurate, or how finely resolved, the boundaries on Edgemaster's map are? Perhaps +/- 1 metre, more, less? Assuming the map to be accurate to within the width of the green line, I get the following ...

New Southgate: Boundary of Barnet and Enfield (boundary runs along railway with one platform in each borough)
Falconwood: Boundary of Greenwich and Bexley (station is mainly in Bexley, but platforms appear to extend beyond the boundary)
Lower Sydenham: Boundary of Lewisham & Bromley (station is mainly in Lewisham, but platforms appear to extend beyond the boundary)
Therapia Lane: Sutton (having looked at the even more detailed map available from Sutton Council's website, I don't see any part of the tram stop touching Croydon). [This last comment edited]

[Edgemaster]

Does anyone know how accurate, or how finely resolved, the boundaries on Edgemaster's map are? Perhaps +/- 1 metre, more, less? Assuming the map to be accurate to within the width of the green line, I get the following ...
[snip]
Therapia Lane: Sutton (having looked at the even more detailed map available from Sutton Council's website, I don't see any part of the tram stop touching Croydon). [This last comment edited]

I myself don't know how accurate they are for sure, the OS claim:

Code: Select all

Zoom Level  	Raster data shown  	boundaries Resolution
10 & 9 	Streetview 	5m
8 & 7 	1:50 000 	20m
6 & 5 	1:250 000 	200m
4 & 3 	MiniScale (1:1M) 	500m
2 	Overview 	1000m
1 	Overview 	2000m
0 	Overview 	5000m

So, 5m at the highest zoom levels. The width of the green line is an arbitrary selection of 3px.

The Sutton map doesn't differ too much from my map, except for a little (minor) simplification in places on mine. I'm assuming both are using the canonical OS BoundaryLine dataset.

The one unfortunate issue with the map is that it hardly labels tram stops, requiring a considerable amount of guesswork.
I'll see if I can hack in Google Satellite imagery.

[jbom1]

I found that the highest zoom settings of the Sutton map, 1:2344 and everything finer than that, mark the boundaries of individual properties and adequately label Therapia Lane tram stop.

[Edgemaster]

I found that the highest zoom settings of the Sutton map, 1:2344 and everything finer than that, mark the boundaries of individual properties and adequately label Therapia Lane tram stop.

So it does, my apologies, I'm mixing up so many of these government provided mapping sites. (There's a few that reach the same limit as mine, and a few that go one further but in monochrome etc)..