We study the temporal evolution of the structure of the world's largest subway networks in an exploratory manner. We show that, remarkably, all these networks converge to a shape that shares similar generic features despite their geographical and economic differences.
A long-time limit for world subway networks
Camille Roth, Soong Moon Kang, Michael Batty and Marc Barthelemy
J. R. Soc. Interface
Published online before print May 16, 2012