Even though the following quote has nothing directly to do with urban experiments, it implicitly does within each of us. I've learned this lesson even recently in my life that many things get worse when we try to force things in our lives. The same applies to our towns and cities. Anyway, here's the quote from Thomas Merton:
One of the strange laws of the contemplative life, is that in it you do not sit down and solve problems: you bear with them until they somehow solve themselves. Or until life solves them for you.