… think about subway maps, which are abstracted from the complex shape of the city and are focused on the rider’s goal: to get from one place to the next. Limiting the detail of each shape, turn, and geographical formation reduces this complex data set to answering the rider’s question: “How do I get from point A to point B?”
Harry Beck invented the format now commonly used for subway maps in the 1930’s, when he redesigned the map of the London Underground. Inspired by the layout of the circuit boards, the map simplified the complicated Tube system to a series of vertical, horizontal and 45o. diagonal lines. While attempting to preserve as much of the relative physical layout as possible, the map shows only the connections between stations, as that is the only information that riders use to decide their paths.
Esse trecho está no livro da coruja do Ben Fry.
Veja também alguns mapas do transporte de Londres.