Increasingly we leave traces of movement, from GPS enabled devices and RFID transport cards, or ‘wired’ infrastructure.
Anil has been producing what he calls ‘ﬂowprints’ of cities. These visualise the city of ﬂows. This is a ﬂowprint of the London Bus network, which contains about 30,000 bus stops. Each dot is a bus adhering to one of 700 routes on the network. He has used simulated ﬂows in this ﬂowprint, incrementally adding more and more buses evenly to each route, in order to show certain properties of the network structure.
He keeps adding buses till we reach about 8000, which is the actual size of the London bus ﬂeet. The brighter areas are where routes overlap or converge. These tend to be bus depots around the outskirts of the city, or the core of the network, which you can see in the middle. This is the historical center of the network, around Victoria, and a great example of what complexity scientists call ‘path dependence’: the capacity for small decisions or events to take a complex system in a completely different direction, constraining and dictating its future growth, disproportionately influencing its future. Because of location choices made 150 years ago in 1860, the network evolved around Victoria Station as its center, and to this day it contains the highest convergence of routes on the network.
These ﬂowprints are like ‘macroscopes’ for cities. They allow Anil to look at the dynamics of the whole city functioning at once whilst preserving a high level of detail.
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