How many people live in Tokyo?

Back in August 2014 when I was preparing some material for teaching students how to query data in a GIS, I devised a very simple example where they had to select all the countries in the world with a lower population than the Tokyo Metropolitan Area (or Greater Tokyo Area, as it's sometimes called). I did this just as an example but since I found the results quite interesting, I quickly turned it into a map and posted it on Twitter, complete with 'Toyko' typo in the subheading. It was really just a quick example of how to query data in a GIS but it also highlighted the massive population of the Tokyo metropolitan area. You can find the full size, original image here. I was prompted to write this blog because the map was reposted on the Canadian Twitter feed @AsapSCIENCE a few days ago and since then my inbox has been a bit busy.

Now, back to the original question of how many people live in 'Tokyo'. Well, when I say 'Tokyo' in the map, I'm referring to the wider metropolitan area, which in 2014 the United Nations World Urbanization Prospects said has a total population of 37,833,000, far beyond the next largest urban agglomeration, Delhi, at 24,953,000. By way of comparison, using the urban agglomeration population (rather than a city's administrative boundaries), Toronto had 5.9 million, London had 10.2 million and Beijing had 19.5 million. Clearly, these definitions include other urban places that are not Tokyo (e.g. Yokohama) but they are recognized as being part of a fairly coherent metropolitan area. 

So, in the map, I'm using a figure of 'approx 36 million' as I say but in reality the UN figure is a bit higher. If we want to narrow the definition down to just the inner urban area then obviously the figure reduces significantly. I'm not usually one to cite Wikipedia, but in this case it's a good place to go to learn about the various definitions of the Greater Tokyo Area/Kantō region. If you don't want to click, here's a summary of some Tokyo populations...

• Former city area (23 'special wards') - 8.95 million people
• Tokyo Metropolis - 13.05 million
• Tokyo Metropolitan Employment Area - 31.70 million
• National Capital Region - 43.47 million

If we take the metropolitan definition used by the United Nations, then Tokyo does indeed have more people than Canada, at 35.5 million (2014 Statistics Canada estimate) and far more than Australia at 23.7 million (see their population clock). The Tokyo metropolitan population is roughly the same as the whole of California, which currently stands at about 38 million.

Link to chart

This was all just a little bit of map trivia and whilst it seems to have annoyed some people who live in a red country, the point was just to demonstrate the simple analytical power of GIS in addition to the size of Tokyo (to make it more interesting). The data I used are from Natural Earth if you want to have a look yourself and the software I used is a free GIS called QGIS, which is really good. Some other random facts about what happened to my original tweet...

• It was tweeted by Guardian Cities and then retweeted 309 times and favourited 107 times.
• It was tweeted by AsapSCIENCE on 22 January 2015 and since then retweeted 96 times and favourited 110 times.
• Akihabara News wrote an entire article about the map, and even spelled my name correctly - that hardly ever happens.
• Tokyo Desu also did a piece on it - and added another map too.
• What does it all look like on the ground? This photo (below) from ATBREAK gives you some idea.

Tokyo metropolitan area

Manchester: a "Northern Powerhouse"

The announcement yesterday from the Chancellor that we need a "Northern Powerhouse" in England was greeted with much enthusiasm - and also a good bit of cynicism, given that it's not far from the General Election. After the announcement, the BBC asked whether more English cities should be like Manchester. What I wanted to know was how this nascent northern powerhouse compared to the already established southern one (London, I think). We all know the numbers - well most do - but what about spatial scale, density and visual comparisons? Given a previous bit of mapping on the urban fabric of England and the fact that I've been thinking about the 'underbounded' nature of the City of Manchester (as opposed to the city region), I thought I'd go a bit further with this post.

The first image here shows how Greater London compares to Greater Manchester - they're mapped at the same scale - and I've also put the Greater Manchester boundary over Greater Manchester and vice versa, just to show that they're not that radically different in size.

Greater Manchester - a large urban area (higher res version)

I've also produced the same image without the respective boundaries overlaid on each city, just to provide a quick visual comparison at the same scale.

Click for higher resolution image

Finally, in order to demonstrate the way in which the City of Manchester is really 'underbounded' in relation to its wider city region, I've shown just the urban fabric of the City of Manchester (i.e. building footprints) in relation to the ten local authority areas of Greater Manchester, beside Greater Manchester as a whole. 

Click for bigger version

I have some even higher resolution images if anyone is interested - if so, feel free to get in touch via e-mail or twitter (@undertheraedar). I just wanted to produce these images to illustrate the fact that Greater Manchester is actually very big (about 80% of the size of Greater London in area) though of course has far fewer people (about 33% of the population). It does seem like the most likely 'northern powerhouse' in England and it will be very interesting to see how things pan out over the coming years.

The Geography of New York City

In June 2013, the city of New York released as open data one of the most detailed, fascinating and user-friendly datasets ever. The Property Land Use Tax lot Output (PLUTO) dataset is essentially a record of every parcel of land in the city, what is on it and who owns it - but this is only part of it. See the full PLUTO data dictionary for more on this. Wired said the mapping elite were 'drooling' over it and there have been a few impressive visualisations already but I was keen to look at the data in more detail and then map land use patterns and get to grips with the dataset more generally. So, as an initial experiment, I mapped all 11 land use categories for the whole city in 3D (PLUTO has a field for number of floors so the maps below are extruded on this basis). Click on an image to enlarge and then flick through the images to compare land uses.

I've also put these images in a PowerPoint file in case anyone finds it useful... These visualisations in many ways tell us what many New Yorkers already know but the PLUTO data (n.b. I've used the ready-made MapPLUTO shapefile) offers everyone for the first time the opportunity to explore this open data and examine the geography of New York City as a whole in much more detail. 

Some further information about the dataset. There are 857,879 rows in the complete dataset and the MapPLUTO version has 85 fields so if you want to work with it then you better have a good computer. When you go to the download page you'll notice that the PLUTO dataset is available as one csv file while the MapPLUTO data is split into the five boroughs of New York City. 

This is an amazing resource but it is not perfect - as the Department of City Planning recognise when they say 'PLUTO is being provided ... for informational purposes only'. The data are only as good as the sources, and sometimes when you look closely things seem a little strange. For example, here's what you get when you chart the YearBuilt column for all buildings constructed since 1800 (click to enlarge). It's hard to tell but I reckon that from about 1980 onwards the YearBuilt column is pretty accurate but before that is is something of a best estimate - though I'd be happy to be proven wrong on this!

I'll probably come back and explore this again soon but that's all for now...


Footnote: 0.4% of tax lots and 1.0% of land remains unclassified. I produced the 3D maps in ArcScene and then annotated them in GIMP. I've just done these to explore at a basic level the characteristics of the dataset and the geography of land use in New York City.

Smarter Cities - IBM

Over the past few years there has been a growing awareness of the ways in which technology can help cities work more effectively and efficiently. One major initiative in this vein is IBM's Smarter Cities project/programme, which is all about being 'smart' as cities grow and grow and consume more of the world's resources.

Why IBM are doing this, the rationale behind it and the steps they are actually taking are on their website, but here's how they start explaining it all:

"In 1900, only 13% of the world's population lived in cities. By 2050, that number will have risen to 70%. We are adding the equivalent of seven New Yorks to the planet every year.

This unprecedented urbanisation is both a sign of our economic and societal progress and a strain on the planet's infrastructure. It's a challenge felt by mayors, heads of economic development, our schools, police chiefs and other leaders who each help to build and support the communities in which we live.

The challenges these leaders face — educating the young, keeping citizens safe and healthy, attracting and facilitating commerce, and enabling the smooth flow of planes, trains, cars and pedestrians — are compounded by the global economic downturn.

Thankfully, help is at hand. Around the world, intelligence is being infused into the way our cities work."

For more on the above, see the short pdf document...

I've just highlighted the UK section of the IBM Smarter Cities site here but it does refer to places across the globe and in the Case Study section you can see examples from Alameda, Queensland and Madrid, among other places. There's even a story about 'CovJam' - click the link to find out more and watch the video below!

The IBM site is certainly worth a look...

There is a special conference on this theme at MIT in April, called Forum on Future Cities, which is likely to be very interesting.

How Many People Live in Inverness?

Coming back to a familiar topic here - that of the population of places. It is interesting in its own right - see this site for information on everywhere, but it is also pretty important in terms of policy formulation, implementation and delivery. Examples include Manchester's missing 25,000, (which equates to £7.5m in funding) and Slough's undercount of new migrants from outside the UK (which also has relevance for the Inverness case). Inverness is where I'm from and it's grown pretty quickly in terms of population over the past 20 years in particular, but there's some doubt as to exactly how many people live there. Everyone has ideas about this - from more generous figures (giving a 'city-region' population of 66,000 in 2001) to figures for the 'city' itself - a rather more conservative 40,949. This just illustrates the inherent difficulties in defining the population of places that have no statutory boundaries. Even if that was the case, the difference between city populations and urban area populations is often very large, as in the case of Manchester (the district) and the Manchester city-region.

So, I've done a bit of analysis, as follows. I attached the data zones for the Inverness city area (core city plus Smithton, Balloch, Culloden and other bits here and there) to the data zones for which we have mid-year 2006 population estimates and come up with a population of 54,685. I make no claims that this is a definitive representation of the population if Inverness but it does give an idea of how many people live in the area shown in the image below showing the google map of the population of Inverness that I've created. [The map may take a moment to load over a slower connection and I may eventually move it off the server it's on right now so the link may eventually die, but the screenshot below is good forever.]

So, once and for all the question has been answered. Or has it?

How Many People Live in Manchester?

A quick post on a common urban theme. Answering the question of how many people live in a city is very tricky. Do you use the political boundaries of the local authority? Do you use the extent of the urban area? Do you use some other definition? In a completely unscientific experiment, I've developed a different approach - and it turns out that the populations I come up with are not that different to those given for the city-regions of the places on my list.

Here's what I did... I took the eight core cities in England, plus London and chose the main central train stations in each of them as the central location (e.g. Lime Street in Liverpool). Then I used a bit of GIS wizardry to calculate the population within a 15 mile radius of said stations (statistically significant distance determined after much spatial analysis... and a bit off the top of my head). Here's the results (using ancient 2001 Census data):

Obviously, these figures differ a lot from the local political entities with the same names (e.g. Manchester the district has about 430,000 people). Even though I've used a fairly arbitrary technique, the populations are a much better reflection of the urban population than others often cite. So, let's compare the figures. On Census day in 2001 London had 7,172,091 people, Birmingham city-region had 2,693, 917, Manchester city-region had 2,482,328 and the other cities on the list show similarities to the 15 mile figure. What does this tell us? Not much really, except that if we use a 15 mile buffer from central train stations we get a good approximation of city-region populations for the major English cities. Here's how it looked on the map: