BBC:
From Beijing to Barcelona, all subway networks share similar
generic features, according to
a
study published yesterday in the
Journal of the Royal Society Interface. Despite
differences in when they were built and where, all systems seem
to evolve and self-organize in mathematically similar ways:
"The number of branches scales roughly as the square root of
the number of stations, the current proportion of branches
represents about half of the total number of stations, and the
average diameter of branches is about twice the average radial
extension of the core," write Camille Roth and coauthors in
their paper. They surmise "the existence of dominant, universal
mechanisms governing the evolution of these structures."
