President of the New England Complex Systems Institute, Yaneer Bar-Yam, gives a talk to Wikimania conference in London recently.
From about 25:00 to 35:00 he talks about the contrast between hierarchical systems and complex networks and how/when hierarchical systems fail. It took me about five listens to fully grasp what was going on, but when listening think about the way we design road networks, particularly hierarchical, dendritic systems, which funnel traffic to bigger and bigger roads (the modernist approach and the predominant paradigm for past 80 years, still clinging to life in Texas) vs multiply interconnected, reticulated grid networks.
The hierarchy fails when the bigger system overwhelms the highest order in the hierarchy, the largest individual. In transportation, that's the biggest highway and thus, when thinking within this outdated logic the response is to expand the capacity of that individual rather than thinking within the frame of a complex system, the capacity of the network, of multiple routes, and multiple modes of transportation.
It's why center cities don't fail when they shed themselves of their inner-city highways, but rather upgrade to 2.0, a new more adaptable, more complex, smarter system.