I mentioned in another comment that I once read a book which mentioned this paradox. That book gave the example of a major street in Manhattan which was closed

I mentioned in another comment that I once read a book which mentioned this paradox. That book gave the example of a major street in Manhattan which was closed for a while; this surprisingly made traffic generally better. Unfortunately, I can’t remember the street, or when this happened, though it might be possible to look it up. (I’d like to know!)