Author: Oliver O'Brien

Washington DC Cycle Commuters Suddenly Appear

Post author By Oliver O'Brien
Post date 5 May 2011
5 Comments on Washington DC Cycle Commuters Suddenly Appear

One of the striking aspects of the US bike share schemes thus far is that they have generally been dominated by weekend use. There has been some weekday use but not a large commuter morning/evening surge, like has been seen consistently in London. However Washington DC at least seems to have reached a turning point, with the characteristic commuter spikes starting to appear, and a post-pm-peak distribution of bikes that had a distinctly London-esque blue in the middle (few bikes in the centre of Washington DC) and red on the outside (presumably more residential areas).

As Washington DC is joining London’s characteristic commuter “tidal flow”, London itself seems to be moving away from that. “Casual” use combined with unseasonably hot and sunny weather here, has meant a “tourist” afternoon surge, always seen at weekends, is present on weekdays now too. This somewhat dilutes the evening commuter use, although the system still ends up quite unbalanced at the end of the day.

I’ve made a minor adjustment to my bike share map statistics (see the “graph” link) – namely the one on the current number of bikes predicted to be in use. I’ve removed this statistic now. Previously, this assumed that the highest number of bikes available in the preceding 24 hours indicated the lowest moment of use. This is the case if no bikes are marked as faulty (or no docks are added to/removed from to the system) – however it turns out this is a significant number, at least in London. When a bike is marked as faulty, at least on the London system, then both the bike and the dock are removed from the availability numbers. By plotting this on a graph, estimates can be made of the number of bikes being marked as faulty each day. At the moment, this seems to be about 5-10% each day for London. Such bikes then get taken to the workshop, fixed, and appear to be replaced en masse just before the morning rush hour:

So now I look at the minimum number of free docking spaces in the last 24 hours instead. This should avoid the poor numbers after a heavy day of usage, where several hundred still appear to be in use at around 2am, whereas actually they are just bikes that were marked as broken on that day, on the stands. I have instead replaced it with a statistic showing the proportion of docks that don’t have bikes in them. This is effectively the same statistic as before, but now I don’t make assumptions about the “baseline” value, i.e. when no bikes are supposedly being used. In other words, previously I was effectively substracting a percentage from this value, based on the baseline percentage. I’m no longer doing that subtraction.

Finally, Toronto and Tel Aviv have just gone live with their bike share schemes, and have been duly added to the map. Ottawa, Boston and Antwerp are all launching in the next month or so.

[Update – Those missing the # number of bikes measure for Washington DC/Arlington can find it here. These measurements are carried out a different way – by looking at changes in individual docks.]

Data Graphics

The iPhone Locations DB – Fun, but not Accurate

Post author By Oliver O'Brien
Post date 3 May 2011
2 Comments on The iPhone Locations DB – Fun, but not Accurate

As a followup to my previous post about the (re-)discovery of the iPhone locations cache, the graphic above shows the apparent locations (of known mobile-phone masts and wifi) that were captured on my iPhone, over the last couple of weeks while I have been in Scotland. These were either independently detected by my iPhone and georeferenced using a built-in service, or, more likely as it turns out, the details of supposed nearby masts were downloaded by my iPhone from this service, based on its own location, in the hope they would subsequently be detected and allow for quick positioning.

The graphic is from my hacked version of iPhoneLocator, changed to show a higher density of dots and include the wifi data. I have superimposed on the map red lines showing where I’ve actually gone over the break. Some of the detected (or downloaded in the hope of detection) mobile-phone masts were over 40 miles away from where I actually was. Some of these may have been when I was on top of a Munro (i.e. over 3000 feet up) which therefore affords a good line of sight. Or simply, there were so few in the area, that details from the far-away ones were the best available to be obtained.

If I hadn’t drawn the red lines, you would probably be surprised to discover, for example, that I never went to Inverness during this trip (the big patch of yellow circles in the very top part of the map extract. I also never went along the various roads visible in the north, west or east part of the map, but my phone still saw the towers in these locations. So to conclude, take the detected locations with a pinch of salt. They tell you where an external database thinks a cell-phone tower once was, or where the nearest few are, even if they are a long way away. They certainly don’t tell you where you’ve actually been…

Reviews

Review: Map of a Nation – A Biography of the Ordnance Survey

Post author By Oliver O'Brien
Post date 1 May 2011
1 Comment on Review: Map of a Nation – A Biography of the Ordnance Survey

Map of a Nation, by Rachel Hewitt, comes in a large, chunky hard-back volume with a beautiful, gold-laced front depicting one of the Ordnance Survey’s earliest First Series maps, dated 1810. The book documents, in often immense detail, the early history of the Ordnance Survey – from the activities leading up to its creation in the early 18th century, to the publication of its final First Series map in 1870.

Rather than being a general history of the OS, the book focuses on the lives of its first director generals, Mudge and Colby, and Roy, whose work led to the creation of the organisation. It details particularly the trigonometric survey, under which an accurate triangular network of known points was gradually built up, and the creation, alongside, of large and small scale maps.

The book is therefore somewhat misnamed – it’s really “Ordnance Survey: Its Birth and The Early Years”. I was disappointed that there is little discussion of the OS’s history after 1870, apart from in a brief Epilogue. The organisation’s more modern history was what indeed I had been most looking forward to. The cover notes mention a Ph.D thesis written by the same author a couple of years before the book’s publication, and I wonder if the book is largely based on the thesis. The language in some parts of the book is also quite formal, with the prose being sometimes on a level consummate with a professional thesis but a little above what would normally expected for a popular book. (A very flowery way of saying I didn’t understand every word in the book!)

The pacing of the book is generally quite good, it is on a near chronological basis, although does tend to jump back in time briefly for short sections. Perhaps too much time is spent on the pre-OS period, important though it is – the detailed biographical sections of the principal people involved, prior to the organisation’s foundation, weighed the narrative down a bit. Later on, the book’s pace picks up. The latter half of the book details the slow progress towards completion of the First Series, with various delays caused by creation of the Irish Survey and expeditions to Sinai and so on.

The book includes a short plate section with colour extracts of various paintings and maps. It is a pity though that it has no photographs of, for example, the monuments showing the endpoints of the original baseline across Hounslow Heath. (See these pictures by Diamond Geezer.)

A note for those that measure their progress through a book by the position of their bookmark – the narrative ends quite abruptly 114 pages before the end, with the rest taken up by the extremely comprehensive citation marks, citation references and index. Again, very worthy for a thesis – the content has been researched extremely thoroughly – but slightly overwhelming for a book like this.

In all, a rigid, well written and authoritative discussion of the first part of the Ordnance Survey’s history, but I was left wanting for more. This is not the OS’s complete biography!

You can see the book on Amazon. A paper-back edition is coming out in July.

Leisure

Munroist in Progress

I’m currently in Scotland for the extended Easter/Royal Wedding/Bank Holiday break, and have been taking advantage of the current unusually fine weather – and a special cheap train fares deal – to make multiple excusions up into the Highlands to indulge in a spot of Munroing – climbing a few of the 283-odd peak in Scotland that are over 3000 feet and so become “Munros”. So far I’ve been twice up on the West Highland Line to Loch Lomond and to Tulloch, and tomorrow, if all goes to plan, I’ll be up in Glen Tilt tomorrow.

If you are ever travelling on the West Highland Line, which by some measures is the world’s most scenic railway, I recommend sitting on the left going up – or the right going back down. With the exception of the Loch Lomond section, the views are generally finer on that side. Particular highlights are the elevated views over Loch Long, Loch Lomond, Loch Tulla and Loch Trieg, and to several of the many mountains – The Cobbler, Ben Lui and Beinn Dorain to name but three. The Cobbler is too low to be a Munro itself, but its three thrilling summits (one requiring a scramble, one requiring an exposed move and one perched above overhanging cliffs) make it far finer than its surrounding Munros. It is one of the classic mountains of Scotland.

Obviously the Glenfinnan Viaduct (hello Harry Potter) and the rest of the section that continues to Mallaig is also incredibly scenic, but I haven’t made it that far this time, partly because there aren’t many Munros that far along and partly because the train takes over five hours to get there from Edinburgh…

The photograph above, which has come out surprisingly well on my geriatric 3-year-old iPhone, was taken on Wednesday and is looking south over to Loch Trieg, from the summit of Beinn Teallach, a mountain which has the dubious distinction of being the lowest of all the Munros.

Bike Share London

Dock Monitor – Keeping an Eye on Boris Bike Docks

Post author By Oliver O'Brien
Post date 26 April 2011
1 Comment on Dock Monitor – Keeping an Eye on Boris Bike Docks

Transport for London have gradually been adding docking stations to the Barclays Cycle Hire network in central London – and occasionally they remove, rename or relocate the existing ones. TfL do now have a webpage which is manually updated with docking station news, but there’s no good way to spot when a new docking station might have appeared in your neighbourhood – without coming across it accidently or waiting for the official page to be updated, so I’ve created Dock Monitor. It’s a blog that is automatically updated as soon as new docking stations appear, or changes happen to the existing ones. Every hour, a script downloads the latest list of stations from the official map, compares with its existing list, and then submits new blog posts as appropriate.

Changes happen surprisingly often. Docks often shrink in size to 0 as they are temporarily operated on (rather than disappearing from the map or having their status changed to not installed.) New docks are sometimes put in with the wrong name or location, these normally get corrected soon after. To try and cut down on the noise, I only post about size changes where more than 20 docking points in the dock are affected, and docks have to have been missing for more than 48 hours before I announce these. TfL has also been changing the IDs associated with some of the docks – which is not something that impacts people using the system, but is a big headache for third-party developers who were hoping that TfL’s IDs were going to be canonical. Looks like I’ll need to create my own set of IDs… Anyway Dock Monitor should spot this too.

Because the blog posts are automatically made, then a data error at source may course a massive burst of blog posts to appear. If this does happen, I’ll try and manually clean up the blog once I notice it.

You can see Dock Monitor here (or subscribe to the RSS feed). You can also view just newly added docks, or the corresponding feed.

Bike Share

Easter Sunday – Big Bike Share Day

Post author By Oliver O'Brien
Post date 24 April 2011
No Comments on Easter Sunday – Big Bike Share Day

It’s Easter Sunday. In England at least, the shops are closed, public transport is restricted, and it’s a warm and sunny day. What better to do than get out on the bike. And if you don’t have a bike, the centre of many of the world’s capital cities now have cheap bikes to rent. So, today is likely to one of the biggest days for bike share so far.

Here’s a league table for some of the bike share cities I’m tracking, based on today’s figures. My metric is based on the maximum number of bikes simultaneously being used. It doesn’t take into account bikes being redistributed, breaking or being added to (or removed from) the scheme today, and assumes that at some point overnight, no bikes were being used before.

% of Bikes in Simultaneous Use – Selected Cities

City	No of Bikes	Max Use %	Time of Max Use (Local)
Washington DC	872	37% HUGE!	16:04
Miami Beach	427	37% HUGE!	14:04
London	4239	35% HUGE!	17:06
Vienna	823	29%	16:42
Mexico City	1162	26%	12:48
Bordeaux	1190	22%	16:24
Barcelona	4327	11%	19:34
Minneapolis	573	9%	16:48

Note: Above 30%, the system is extremely busy and it becomes very difficult to find a bike in many places.

America is beating Europe!

Photo by Infomatique on Flickr.

Data Graphics London

Your Life on a Map – Thanks to the iPhone

Post author By Oliver O'Brien
Post date 21 April 2011
2 Comments on Your Life on a Map – Thanks to the iPhone

A recent discovery, revealed at the Where 2.0 conference, of a hidden file on iOS4 iPhones and iPads (and on computers that they are synchronised to) is proving to be rather interesting find. The file contains a couple of tables – ‘CellLocation’ and ‘WifiLocation’ that contain records showing times, locations and accuracies of mobile phone masts and wifi points that your phone has come across. [Update: Or more likely, ones that you might expect to come across, based on your current measured location or existing detected masts/wifi.] iPhoneTracker is a great utility which finds the file, parses and displays a gridded heatmap of the places that your iPhone thinks you’ve been to. In my case, it reveals my various trips around London, to towns in England and my travels up to and around the Scottish Highlands in the New Year.

Here’s what a bit of the wifi data on my phone looks like:

You can even see all the MAC addresses of the wifi points (and their locations/accuracies) – again this is nothing you couldn’t collect, and indeed is what Google was busy collecting with their StreetView cars, along with the 360-degree photos. Unfortunately for Google, they also collected the unencrypted data coming from some of these wifi points, which landed them in a bit of bother.

The iPhoneTracker application, as run, grids the data to 1/100th-degree latitude and longitude squares, and only looks at the mobile-phone mast data, rather than the wifi data, as the latter is more likely to be inaccurate (it’s reliant on a look-up database which can go out of date quickly). However, a simple change and recompile of the application in XCode (it’s open source) allows a more accurate map to be included, along with the wifi data if so desired.

The map above shows my travels around London in the last few months, including both the mobile-phone mast and wifi data – the former is generally less accurate and so your location tends to wander, so it shows as circular clumps of small yellow dots. The latter is more concentrated so shows up as the red/purple larger dots, but in fewer locations.

As well as the positional random inaccuracy of the cell-phone triangulations, resulting in these distinctive circles of yellow dots, there is sometimes a systematic inaccuracy. I am 99% sure I haven’t been to East Ham/Barking in the last nine months, but there’s a distinctive clump around there (far right of the screenshot above.)

I’m not going to get into the debate about why Apple has persisted such a file on your phone (and in the computer backup) or whether it’s a good thing that this data is so easily accessible. It’s nothing that’s not on the mobile phone companies’ own databases. The big deal is now you can play with your own location data (and so can someone swiping your computer.) I guess if you don’t have any secrets to hide it’s a great, if imprecise, insight into your spatio-temporal life – tracking how you move around your hometown and indeed the world (my set includes my recent trips to Sicily and Prague).

The background map is from OpenStreetMap. iPhoneTracker is proving so popular, since it was revealed yesterday, that it has quadrupled the normal daily number of map images being served from the OpenStreetMap servers. The gridded visualisation is from OpenHeatMap, written by the same author as iPhoneTracker itself. It’s a great way of showing imprecise, large-volume spatial data like this.

Bike Share

Cartography Update for the Bike Share Visualisation

Post author By Oliver O'Brien
Post date 19 April 2011
1 Comment on Cartography Update for the Bike Share Visualisation

I’ve refreshed the cartography for my bike share visualisation – the grey background, with dark grey rivers, was looking a bit, well, grey. The rivers are now a nice shade of blue, with the land a bit browner. I’ve also fixed the display of the visualisation on iPhones and iPads (and presumably other portable devices.) It now uses the new “touch gestures” code in the development (unreleased) version of OpenLayers, allowing people to pinch, zoom and pan with their fingers. I’ve also done a general tidy of how the information is displayed, at the top and the bottom of the screen, taking out some of the clutter and highlighting the key numbers more prominently. The animated version has also had a spring clean.

Finally, I’ve added in San Antonio, Chicago and Des Moines bike shares. These are all quite small schemes, but they use B-Cycle technology, which means pulling in their data was very easy to do – it’s exactly the same as for Denver, which I already had.

There is also a small change in the statistics – the “max today” stat is now based on the local time for the bike share, not London time.

Next on the to-do list is to add the current weather, and display the time in the local time zone, rather than the time on your computer. Also I look forward to seeing the data from Torontoand Ottawa in Canada and Boulder in Colorado, US. Both schemes are launching in the next month and look to be quite large so will provide a good insight into the movement of the respective cities. Watch out Europe, America is catching up and with systems that provide excellent data (Bixi and B-Cycle) they’ll overtake you!

Orienteering

Varsity Match 2011

I was the Czech Republic over the weekend, at Doksy, which is north of Prague and near the German border, for the 2011 orienteering Varsity Match. After a “model event” on the Friday to familiarise ourselves with the sandstone terrain, the match itself was on Saturday, and a 3×2-man relay on the Sunday.

The sandstone terrain is quite distinctive – lots of rock pillars and cliffs, generally 5-10 metres high. The cliffs occur in lines, meandering horizontally but generally at the same height. This means that natural terraces between the cliffs provide opportunities for fast, level running, in terrain that first glance looks intimidating. Groups of rocks often have distinctive horizontal breaks, often occuring at right-angles to each other, resulting in “sandstone cities” – passages which can be navigated along between the rocks. The passages are generally less than a metre wide with vertical rock on either side. Careful mapreading is required to ensure the route followed doesn’t lead to a dead-end or a rocky drop, but the modern maps we used during the weekend have been produced to a very high standard by the stanstones.cz team.

The model event had plenty of controls in “theatrical” locations such as narrow rock passages, with some crag-hopping possible in a couple of locations. The actual varsity match though was mainly about good route choice, i.e. go through the complicated terrain, or go around, or (sometimes) choose a shorter but steeper way around. As I was walking the course (as injured) I generally opted to go straight – less walking, and also generally the more scenic option.

Here’s my route between 6 and 7, following a terrace between two sets of sandstone cliffs. You can also see some sandstone cities, NW of No. 7, although my route didn’t visit them.

Results and course maps.