Friend and colleague Gail Hamner posted on FB this article, which you can read here, about “defensive urban design.” Looking a little like installation art in the article, the use of dull little spikes has as its main social function the driving away of the homeless and indigent. Following the same logic, note the middle arm rest on this New York City park bench, which makes it impossible for an adult to lie down, take a nap, or get a night’s sleep.