Scientific American reprints a 2016 article from The Mathematical Intelligencer on an obscure, but important, corner of transit map design: how to choose a colour for a metro line. The discussion is rather math heavy (and therefore above my pay grade), but the gist is that for ease of use lines’ colours should look as different from one another as possible, and it gets more complicated as you add more lines. “Not only must the new colors be unlike the old ones, but also they must differ from each other as much as possible.” The article discusses the math involved in choosing new colours. [WMS]

Previously: The Transit Line Colour Palette.