In the central part of Sao Paolo, there are pretty big dips in the road at each intersection. Think of them as inverted speed bumps.
The primary reason, I’m told, is to control the flow of water during the rainy season (which is intense).
Otherwise, the streets flood (and sometimes even in spite of that).
But, they also have another affect.
It prevents people from speeding through downtown.
One change. Two impacts. Kind of neat.