Too much money, too little time? London’s taxi company Addison Lee is certainly aiming at a certain sub-section of the usual taxi customers, describing itself as a ‘business class car service’. It runs over 4,800 cars in central London and does around 25,000 journeys a day in and around the capital. For an infographic in their in-car magazine Add Lib I created a series of maps analysing and visualising the pick-up and drop-off locations of a typical week of journeys from their full fleet. This is how the drop-off locations were featured in their magazine:
The map shown above uses a gridded population cartogram as a basemap onto which I projected a kernel density estimation of all drop-offs made by their fleet in an average week of journeys in 2014. This is a statistical approach to estimate the probability density function of a variable – which here are the drop off locations of each taxi ride. Calculating the density helps smoothing the data which can then be visualised in form of heat maps where the highest densities become more red in the above map.
In addition to this map, I have calculated the same measure for the pick up locations and mapped both datasets in three different ways, as shown in the following map feature. The first two maps are a conventional land area map of London showing the kernel density for the pick-up (left) and drop-off (right locations. In the second set of maps, this is then projected on a gridded population cartogram where each of the grid cells in the map is resized according to the total number of people living there, resulting in an equal-population representation of the city. The last two maps are a gridded cartogram transformation of the kernel density values themselves, meaning that a grid cell is larger if there have been more pick-ups/drop-offs in an area, highlighting those areas most that are shaded red in the upper maps (the colour key is oriented on the colour scheme that I developed for the Londonmapper project with each colour representing an individual Borough of London – see the reference map there for a guide to the colours):
Though there is variation in the places that people come from and go to, the majority of places that these taxis serve is concentrated on Central London and the two airports (Heathrow in the west and City at the Thames in the east) within the urban boundaries. In Central London, not only the busiest parts of the city in terms of commercial activity, but also the wealthier residential areas (and boroughs) stand out – certainly caused by the distinct customer base of the company.