Tuesday, 27 March 2018

Daytime Population Density

My last blog post on population density was basically just a little extract of some work I've been doing on population density. However, density is not absolute or fixed and it can change significantly throughout the day. A variety of sources suggest that the maximum density per square kilometre in the UK is around 25,000. Yet this only relates to where people live. Spend any time in a busy city centre and you'll see far higher densities than this, so I thought I'd take a look at it. To begin with, here's a map of daytime population density in the southern and eastern part of England.

The maximum density during the day is over 125,000 per sq km

As you can see on the map above, when we look at population density during the day, there are some big differences - the most obvious of which are in central London. Compare this to the picture when we look at residential population density, which is how it is usually reported.

This is also useful, but it's only part of the story

This is not particularly surprising, of course, but it is quite striking how large the differences are. Thanks to the folks at the Centre for Ecology & Hydrology, and an open licence, we can look more closely at daytime population density across the UK, as well as residential density, using 2011 data. This can provide us with a much more nuanced view of population density and help us understand how the population distribution changes during the working day. Outside London, the single square kilometre with the highest workday population is in central Glasgow, with over 60,000 people. A little extract of this, and the equivalent residential population is shown below.

Glasgow has the highest daytime population density in Scotland

Edinburgh has the highest residential density in Scotland

With this data we can then drill down to look at other parts of the UK, and this is what I've done in the rest of this post. I've extracted images for all areas where there are more than 20,000 people present in any single 1km cell during the working day, according to the CEH figures. As you'd expect, it includes the major cities but some of the places that do feature may surprise you and some of the places that don't may also. Only places with a single cell containing 20,000 people or more during the working day are shown.

You'll also notice the connection between density and rail infrastructure if you look closely. It often looks like a cable plugged into individual red squares. The upper figure in each image is the daytime population, with the residential figure in brackets underneath. Each cell is, of course, 1km by 1km. Click on the individual images to enlarge.











London - overview 
London - zoomed in

London - Tower Hamlets

London - maximum values







That's it for now. I'll return to look at population density in the future, hopefully once I've finished my current overly-ambitious attempt to derive some new-fangled population density measures for the whole of Europe.

Data source: this data is made available under the Open Government Licence. ©NERC (Centre for Ecology & Hydrology). Contains National Statistics data © Crown copyright and database right 2011. Contains data supplied by Natural Environment Research Council.

Reference: Reis, S.; Liska, T.; Steinle, S.; Carnell, E.; Leaver, D.; Roberts, E.; Vieno, M.; Beck, R.; Dragosits, U. (2017). UK Gridded Population 2011 based on Census 2011 and Land Cover Map 2015. NERC Environmental Information Data Centre. https://doi.org/10.5285/0995e94d-6d42-40c1-8ed4-5090d82471e1