With manners transposed the teatray down to an upturned lithia crate, safe from eyes, low
A study of the world’s largest subway networks has revealed that they are remarkably mathematically similar.
The layouts seem to converge over time to a similar structure regardless of where or over how long they were built.
The study, in the Journal of the Royal Society Interface, analysed 14 subway networks around the world.
It found common distributions of stations within the networks, as well as common proportions of the numbers of lines, stations, and total distances.
Some scientists think that subway networks are an emergent phenomenon of large cities; each network is the product of hundreds of rational but uncoordinated decisions that take place over many years. And whereas small cities rarely have subway networks, 25 percent of medium-sized cities (with populations between one million and two million) do have them. And all the world’s megacities—those with populations of 10 million or more—have subway systems.
