www.guardian.co.uk/science/punctuated-equilibrium/2011/feb/02/1?CMP=twt_fd, posted 2011 by peter in art hack video
In this graphic, when a train departs from its originating station, its path is traced on this webpage as a growing coloured string that is "plucked" by intersecting trains. Just as with a real stringed instrument (a cello in this case), longer train lines make lower notes when "plucked" than short ones. Time accelerates in this graphic, so you can watch a 24-hour train cycle. An interesting addition to this map is the artist's inclusion of discontinued subway lines: these so-called "ghost trains" slip by in the middle of the night.