Subways 'share universal structure', research suggests

[M II A II R II K]

Subways 'share universal structure', research suggests


16 May 2012



Read More: http://www.bbc.co.uk/news/science-environment-18072627

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.

- It found the total number of stations was proportional to the square of the number of lines - that is, a four-fold increase in station number would result in a doubling of the number of lines. The dense core of central stations all had the same average number of neighbours in the network, and in all cases, about half the total number of stations were found outside the core. In addition, the length of any one branch from the core's centre was about the same as twice the diameter of the core, and the number of stations at a given distance from the centre was proportional to the square of that distance.

- "Although these (networks) might appear to be planned in some centralised manner, it is our contention here that subway systems like many other features of city systems evolve and self-organise themselves as the product of a stream of rational but usually uncoordinated decisions taking place through time," they wrote. The authors say that the systems do not appear to be "fractal". Fractal systems follow mathematical patterns that seem equivalent in a number of physical and social systems ranging from the movements of planets to the movements of depressed people, but they may or may not reflect a deeper, more universal organisational principle. Nevertheless, the team wrote that some underlying rule is likely to be driving the way subway systems end up worldwide.

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Slime moulds grow to seek "optimum" networks that parallel subway organisation

[pesto]

Originally Posted by M II A II R II K

Subways 'share universal structure', research suggests


16 May 2012



Read More: http://www.bbc.co.uk/news/science-environment-18072627






Slime moulds grow to seek "optimum" networks that parallel subway organisation

I assume this is a humor magazine?

Theories of this sort are dubious since it is ALWAYS possible to force some mathematical relationship onto any data set. The key is whether the "formula" can be reduced to humanly comprehensible parameters which are themeselves measurable and analyzable. Otherwise, it's just noise.