Here is an animation that Ollie O’Brien created a couple of years ago for the “Sense and the City” exhibition at the London Transport Museum. The map shows the touch-ins (going into the network) and touch-outs (leaving the network) of Oyster cards at London’s tube and train stations, including a few beyond the Greater London boundary which still accept . As the animation moves forwards in 10-minute intervals during the typical weekday, the balance between touch-ins and touch-outs is shown by a colour scale. Red indicates the great majority of taps are touch-ins, and green indicates mainly touch-outs. White is the “neutral” colour, indicating that roughly as many people are entering the network as leaving it, at that period in time.