Hey, Ive never tried streets before, but heres my idea on rubble.
Kind of the same as the one above. First, get an empty CD case and remove everything inside (The paper and the oddly shaped things that hold the CD in place, all are a bit different. Next you mix up some plaster or use extra from another project and pour it in. Close the case and let it dry. Now, it wont come out in one clean slab, you will have to crack and break it out, and in the end this gives you realistic looking rubble, and I have used it for everything from fine "dust" to what looks like chunks of buildings. Just as some helpful ideas, you could try scribing bricks in before it dried, you could stick broken toothpicks in as it dried to look like supports or do other stuff to texture it or make it realistic. Hope this helped.
-EDIT- added a picture of some of my results with this method but it isn't painted yet.
"Scanlon: work your knobby hands on the table in front of you, constructing a make-beleive bomb to blow up a make-beleive world."