America's Waters

There is a characteristic of complex systems that people who study systems dynamics like to point out a lot. It’s called non-linearity — the idea that small perturbations can often lead to major consequences in systems that are sufficiently complex. The “butterfly effect” is a popular thought experiment about non-linearity.

In June of this year, a tanker truck carrying 8,500 gallons of gasoline on Interstate-95 in Philadelphia lost control at an exit ramp resulting in a crash that destroyed a section of the overpass; the driver lost his life in the accident. The repair was originally estimated to take