Five bridges and an eight

Albert is a fine name for a bridge, Battersea a little prosaic. But then comes Cremorne, which is a splendid name for a splendid bridge, even if it was built to carry the less euphoniously named West London Extension Joint Railway over the river. And after Wandsworth, about which there is nothing to say, comes Fulham Railway Bridge, which is unimaginative but exact, with eights shooting unexpectedly from under pedestrians’ feet.

Who pays for footpaths?

Here is a typical English rural scene. It’s early June, the sun is shining, the crops are growing, the footpath skirts the edge of the field, and there is almost nobody about – except a small group of teenagers who have just gone past trying, not altogether successfully, to get their heads round orienteering.

The only slightly odd thing about it isn’t apparent from the picture. This farm is not in some bucolic shire, it’s in Greater London, just 17 miles as the crow flies from Trafalgar Square.

As a Londoner, I think that’s fantastic. I get to go for long walks in the country without going out of range of my oyster card. But it’s also a bit odd. Astonishingly (at least to me), 10% of the land area of Greater London is used for agriculture, with a further (in)decent chunk (or so it feels from walking around and across them) taken up by golf courses. For a city facing acute shortages of affordable housing, that might look like a solution waiting to be seized. But as a post in CityMetric which prompted this reflection notes, the London Assembly Planning and Housing Committee concluded something very different:

There is a good case to be made that commercial agriculture is one of the best and most productive land uses in the Green Belt. The benefits include: opportunities for local job creation, skills development, regeneration, preservation and management of green space, potential for waste management, providing healthy locally produced food and so reducing food packaging and food miles, and the potential for improving food security.

So as ever, there are costs and benefits. I reap some of the benefits (and part of the benefit is that there often seems to be very few other people interested in sharing them) but incur none of the costs. So who is paying for my enjoyment?

One answer is everybody – this is a consequence of a green belt policy and so is a collective self-denying ordinance not to allow alternative uses for the land. There is apparently strong popular support for the policy – but then this is a near perfect example of a policy where a small number of people capture a very large share of the benefits (people who live in or near the green belt) and a much larger number of people share the costs (people whose housing choices are constrained or journeys to work elongated); the first group find it much easier to defend their shared interests than the the second.

Another answer therefore, is that the cost is carried by everybody who could make better use of the land but is prevented form doing so.  The people who would live in the houses which cannot be built are quite literally not in the picture. That leads to suggestions such as the observation by the Adam Smith Institute that a million homes could be built within walking distance of stations in the green belt and in doing so take up only 3.7% of the total area – met unsurprisingly with an equally strong rejection from the Campaign to Protect Rural England (and that such a campaign would concern itself with the rurality of the world inside the M25 is itself cause for reflection).

It seems pretty clear that we are not going to run out of land any time soon – not even of land close to major urban areas. The enjoyment of that land may not have a direct monetary cost, but its preservation does have consequences.

While the arguments continue, I will keep on walking, hoping as I go that if anything is to be built on, it’s the golf courses which go first.

Joining the dots

Lightroom Map

It’s easy to lose sight of ways in which technology can make complicated things trivially easy – not least because all too often, it doesn’t. But it can be a real delight when something just works – and delight multiplied by astonishment when that’s the result of unconnected tools and services interacting with each other.

I go for walks and take photographs. Sometimes it’s obvious afterwards where the pictures were taken, but sometimes it isn’t. So it would be nice if I could tag them with a location. Unfortunately, my cameras don’t know where they are, so they can’t do that. There is a device I could buy which adds GPS to my camera but it costs nearly £200 and by all accounts doesn’t work very well.

It turns out though that I don’t need it. The camera records the time a picture was taken. My phone can very easily – and continuously – record where I am at a particular time. So if the two can be aligned, the problem is solved. The next piece of the puzzle is Adobe Lightroom, which I have used for years without ever particularly noticing, let alone using, its map functions. And it turns out it can do something which feels close to miraculous: give it a standard GPX file with a recorded track, point it to some pictures taken at the same time, and it will tag the latter with data from the former. The only essential to making it work is that the clocks on camera and phone are synchronised.

That’s exactly the promise of the early web, of course: small pieces, loosely joined, as David Weinberger described it. So it’s a little sad that this is in any way noteworthy – but what makes it so is not so much that the pieces can feed each other (there’s no shortage of those) as that it can be done without even the kind of minimal configuration needed by services such as IFTT.

And so to last weekend’s stroll across the prime meridian. Or rather, it turns out at the point this picture was taken, 0°0′31″W.

31 seconds west

London Loop 16 – Borehamwood to Cockfosters

It’s been three months since the last leg of the Loop and suddenly the angle of the light and the colours it picks up are very different.

I went unintentionally off the route three times – more than in any other leg of the Loop. Once was because I was paying attention to the OS map (which was wrong) rather than the Loop directions (which were right), once because I read too much into the angle of a waymarking arrow, and once because the path ahead was broad and tempting and the waymarking which should have alerted me to the turn I should have taken missing or obscure.

And there was one I caught – an avenue rolling out ahead but a turn to be taken to the left. There was a substantial finger post – but it was carefully positioned behind a mature tree so as to be almost completely invisible. Instruction manuals are all too frequently written by people who know how the thing works. They would in many ways be better if written by – or at the very least, tested by – people who know nothing about the thing at all. In the same way, I suspect paths are too often way marked by people who know the way.

Dual carriageway detourThere was another kind of diversion earlier in the route. When the path meets a busy dual carriageway, there is no alternative to walking down one side and up the other, in order to cross the road safely. It adds the best part of a mile in the slipstream of fast moving traffic, a twenty minute reminder that the Loop is in part a grand illusion, rus in urbes.

I walked the last couple of miles through fading light. As the trees became monochrome and their shade steadily darker, only the fallen leaves held some residual colour, almost fluorescing against the surrounding darkness.


Route map for a customer journey

The leg of the London loop I walked in July prompted a paragraph on the glories of the Ordnance Survey map app. The leg of the Loop I walked at the weekend elevates the app to a post of its own, though not in a good way.

I knew I had the Ordnance Survey sheets I needed loaded on my Nexus 7 and that they would be available whatever the state of my data connection along my route. OS stuck update.pngBut the OS app took it into its head to update itself. Or rather to fail to update itself. It got to 33% of something and froze with the excuse that it could not access the internet. There was in fact a perfectly good – if not outstandingly fast – internet connection so the excuse was a pretty thin one. After a few frantic minutes of prodding and restarting, the penny dropped: it was only prepared to update over wifi (though that’s not what the error message said). I got round this absurd problem with an absurd bodge: setting up my phone as a wifi hotspot made the app happy that it was getting data the way it wanted, even though the underlying source was exactly the same as the mobile data connection it had turned its nose up at.

It should be pretty obvious that  updates – particularly updates requiring significant amounts of data – should happen when the user chooses. It should be pretty obvious that the fallback to a failed update should be that the earlier version continues to work, not that the whole app locks up completely. And if progress is being stopped by a preference setting, it should be pretty obvious that giving the choice of changing the preference is better than defaulting to failure.

Eventually the core app did update itself – at which point a new problem appeared. I have 36 OS sheets linked to the app, all labelled according to OS grid referencing, with snappy names such as SH62 and TQ37. OS map install screenAnd every one of them now had to be reinstalled. But of course at that moment, I didn’t want all of them, I just wanted the two needed for the walk I was about to start. There is, as far as I can tell, no way of identifying from the list of available sheets what each of the map areas covers, and while I am proud of my cub scout badge in map reading, I can’t guess the ones I need. There is a decidedly non-intuitive way of working round this problem too, by going through the process of buying the sheets I already own, since doing it that way does show map coverage (though not the map reference numbers) and does install the updated versions without charging for them again. Had I been at home with a good data connection, I would have taken a much simpler approach, and just clicked on update all. Except that there is no such button: to get the app back to the state it was in before OS started trying to be helpful will require 36 manual updates.

All in all, it took over twenty minutes to get a usable map. The one saving grace is that I was on a train – if I hadn’t discovered the problem until I had started walking, I would have been much more irritated.

OS error.pngThen about five miles later, I discovered a very different kind of problem: the map was plain wrong. The screenshot show the west to east footpath passing two footbridges, crossing from the south to the north bank of the Dollis Brook at the more easterly one. It actually crosses at the westerly bridge. Other than the pointless circumnavigation of a field, no great harm was done – but it’s curious that the path on the south bank not only doesn’t exist but can’t have existed for a very long time as there is not even a trace of a gap in the hedge for it to get through to the second footbridge. But at least by that point, I had a map.

Walking round the London loop, an OS map is a luxury rather than an essential. But there are plenty of times and places where a good map is more critical and where a data connection is somewhere between shaky and non-existent. If you can’t trust the OS not randomly to want substantial data downloads and to stop working if it doesn’t get them, you can’t trust it at all. This really needs fixing.

Three pylons and half a transformation

A bullet from a shooting star

I went for a walk to see a pylon. There turned out to be quite a few. Apart from the arty one, there were the ones holding up the roof of the Dome and the one holding up the dangleway.

The inverted pylon is not just an inverted pylon. It is, apparently, A bullet from a shooting star:

Referencing the industrial history of the site which once included the largest oil and gas works in Europe and a steelworks, Alex Chinneck will create a lattice of steel, that resembles an upside down pylon, leaning at a precarious angle as though shot into the earth. The construction and materials will reflect the same visual and material language of multiple structures across the Peninsula, particularly the redundant gas tower located on site while also evoking the idea of power generation and supply.

It struck me looking at the pictures I had taken along the walk – six or seven miles from Greenwich to Woolwich – that most of the structures I had seen didn’t particularly reflect ‘the visual and material language’ of an electricity pylon, whichever way up it might be. But what jumped out at me instead is how many of them could be described using the same word.

I had done much the same walk before, a few years ago now.  The first stretch, leaving Greenwich along the Thames Path, seemed familiar. But soon I realised that a few years ago might be twenty years ago. Acres of what was semi-derelict wasteland have become smart riverside housing, with the patina of newness already gone. What was once mostly a rough and narrow path now has long stretches wide enough for pedestrians and cyclists to be given separate lanes  – though interspersed randomly with stretches where the cycle lane came to abrupt dead ends, and interrupted at one point by a man with a big grabber unloading barge-loads of aggregates. And of course there’s a dome. I don’t think it was there last time I came this way, but then I wouldn’t have guessed that that last time was long enough ago to be back in the last millennium.

Back then, whenever then was, there was plenty of the rich ecology which goes with long and gradual dereliction. Now, with much of the dereliction gone, there is an ecology park instead. Beyond it, just as suddenly,  Angerstein Wharf marks a transition back to an older world, where ‘wharf’ signifies a place to unload ships, rather than flats which few can afford. And so along a seedier and more familiar route to the Thames Barrier, and beyond to the Woolwich Ferry, crossing the river on a ferry built for the world of 1963. It is striking what has been transformed. It is no less striking what has not.


A questionnaire in the style of Borges

As I first noted almost a decade ago in another place, the Argentinian writer Jorge Luis Borges is famous for the classification of animals supposedly to be found in the Celestial Emporium of Benevolent Knowledge:

  1. those that belong to the Emperor,
  2. embalmed ones,
  3. those that are trained,
  4. suckling pigs,
  5. mermaids,
  6. fabulous ones,
  7. stray dogs,
  8. those included in the present classification,
  9. those that tremble as if they were mad,
  10. innumerable ones,
  11. those drawn with a very fine camelhair brush,
  12. others,
  13. those that have just broken a flower vase,
  14. those that from a long way off look like flies.

I am always reminded of it when people start talking about classification systems (and of David Weinberger’s insight that Everything is Miscellaneous).

And I was reminded it again confronted by the survey conjured together by Randall Munroe’s inimitable xkcd:


The individual questions in the survey range from the apparently normal to the decidedly odd – just like the items in Borges’ list. But like the list, it is the set as a whole which is quite gloriously surreal. This is a tiny sample, but I do urge you to look at the whole thing, complete it and revel in it.

XKCD survey extract

I don’t know how long the survey will remain open – its purpose is apparently “to create an interesting and unusual data set for people to play with”. If the questions disappear, I’ll add a screenshot of the whole thing, but as it’s just short of 8,000 pixels long, I won’t if I don’t have to. In the meantime, here’s a final teaser. But the whole thing is better.

FireShot Screen Capture #122 - 'The xkcd survey' - docs_google_com_forms_d_1

Update: The survey has closed and the questions have vanished (at least for now). So here is the full thing. Scroll down – a long way – to get to comments.

The xkcd survey

London Loop 15 – Hatch End to Borehamwood

Another stretch of the London Loop. A few more slightly random thoughts.

London prairie

Obscure waymarkWaymarking on the London Loop is generally fairly good. It tends to be at its best, unhelpfully, when it is least needed. Clear paths with no obvious turnings sometimes provide slightly redundant reassurance with surprising frequency. Very obscure waymarkTricky turns or uncertain directions may have to be negotiated with no hint of guidance. At several point on this section, critical turns onto obscure tracks were marked by signs which were even more obscure. Sometimes even that faint help is not to be found. This is definitely one of the sections where the route notes are essential, as opposed to merely useful.

OS android mapThe other increasingly indispensable tool is the Ordnance Survey map app. At one level, it’s just the paper maps in electronic form, the sort of thing that isn’t supposed to work online. There is nothing about the maps themselves which makes any concession to their transmutation. Except that GPS makes all the difference. I may not be sure that I am where I want to be or should be, but there is now no need for doubt about where I am. And it’s never a struggle to fold on a windy day.

The path emerges from woodland to dramatic views across London. Harrow, it is suddenly clear, really is on a hill. And a constant stream of planes floats past in ghostly silence descending, it appears, towards a huge gasholder in Southall which is by far the most dominant feature of the entire landscape. The planes, it turns out, are precisely ten miles away, beyond the ability of my lens to resolve through the haze.

Final approach to Southall gas works

A little further on, the path skirts the edge of Bentley Priory, the home of RAF Fighter Command, the unlikely combination of a mansion designed by Sir John Soane and the existential struggle of the Battle of Britain. The house can be glimpsed through the trees, closer to hand pill boxes still stand ready for the final defence.

Defending Bentley Priory

One of the things I most like about the Loop is the way it creates illusions of rural tranquillity far beyond the reality of life inside the M25. There are stretches of woodland with not a soul to be seen where only the map reveals the houses an invisible stone’s throw away. There are many places where the only immediate sign of human activity is the roar of traffic from an unseen road. This picture seems to sum that up: climbing a slope through a hayfield suddenly brings a sign into view. There is indeed no hard shoulder – for rather further than 240 yards.

No hard shoulder


London Loop 13-14 – Harefield to Hatch End

Some random thoughts from today’s walk. And a few pictures.

Batchworth Heath

    • On a glorious June day, I met almost nobody in walking almost ten miles, including a stretch of two or three miles where I didn’t see a single soul.

White Heath Farm

    • Whoever knitted together stretches of path and field and woodland to make the London loop was a genius. Part of that genius is in making the gaps in the modern world seem much larger than they really are. But even genius can’t make everything vanish.

Second pylon

    • Another coal post, a relic of the 1860s, marking as it happens the boundary between Hertfordshire and long defunct Middlesex – and with a line clearly visible across the road, where modern road surfacing is still managed along those ancient boundaries.

Coal post on the Middx Herts boundary

    • I lost count of the buttercup covered meadows I crossed.

Woodcock Hill

    • The Loop is the London Outer Orbital Path, which makes calling it the London Loop redundant. On the other hand, just calling it the Loop would be incomprehensible. But I seem to be in good company. Or at least official company.
    • Navigating the Loop is entirely straightforward, except when it isn’t. Here you are on a fine broad path stretching enticingly up the slope ahead of you. There are no signposts or waymarks of any kind. Should you forge ahead? No, you should take the path on the left through the tiny gap in the fence, which barely looks like a path at all, even when you are standing right by it.

The way ahead

    • Wembley Stadium is more rural than you might think – and last seen in section 4, fifty or sixty miles back round the loop.

A prospect of Wembley

    • Trains on the London and North Western Railway, now operating as the London Overground, are air conditioned. This is no small thing.

LNWR Overground

  • It was a beautiful day for a walk.

Variable randomness

The main point of this post is to remind myself of how to solve a problem in the unlikely event that I encounter it again. If anybody else with the same problem stumbles across it, so much the better.

In these modern times, it is easy to quote a tweet on a wordpress blog post – you just put in its url and a kind of magic happens. Back in the olden days, life wasn’t as easy as that, but there was a third party plug in called Blackberry Pie which performed an equivalent function. It broke with an api change years ago, but I still have a handful of its shortcodes scattered across long ago posts.

Most of them are easy enough to fix – the shortcode includes the full link to a tweet which is easily extracted. But Blackberry Pie was smart enough to cope with just the tweet id, and there is no apparent way of recreating the full tweet url from that, since links always include the twitter username.

So I turned to Twitter itself for help.

And help there quickly came.

That looked good in theory, but I couldn’t make it work in practice non-programmatically, even with the authentication keys. Not to worry, more help was to hand.

Well I don’t particularly python, but I was game to try, though this was starting to turn into a more serious enterprise than the size of the task seemed to warrant.

But then I struck gold – though I nearly missed it.

My first thought was that this had missed the point altogether. The link structure

still seemed to need me to know what to put in for the placeholder Tweet_Maker_User_Name, which was precisely the problem I had in the first place. But then it occurred to me that perhaps it was a special code which effectively did the job of the api call and that only Tweet_ID needed to be substituted. And so it proved. The link resolved to the full standard url, username and all. Job done.

But I was still a bit curious about the apparently generic username placeholder and wondered whether it was documented. A search produced precisely one result, a Stackoverflow discussion of the question I had started with. One contributor suggested the Tweet_Maker_User_Name approach – and was squashed by another who made the same misjudgement I had. But the final reply gives the answer I had begun to suspect, that the link structure is not so much


Indeed, even substituting a valid but incorrect username doesn’t cause a problem, the link still resolves to the correct full url, fixing the wrong username as it goes.

Which leaves me with the intriguing twin thoughts that the use of usernames in twitter urls is to help human readers rather than having any technical significance, and that this redundancy appears to be very little known.

And a final serendipitous twist. The Stackoverflow question was posted on 22 May 2009, six years almost to the day before I was looking for the answer. It’s attracted a leisurely eight responses over those six years, the last and most useful of which was posted on 17 May 2015, immaculately timed to be there when I looked for it.

Thanks to Simon Dawson, Chris Yiu and Josh

And further thanks to Adrian Short for providing the perfect postscript:

All long help threads should have a sticky globally-editable post at the top saying 'DEAR PEOPLE FROM THE FUTURE: Here's what we've figured out so far ...'