Designs by Sick has a couple of sets of Road Signs. They are quite nice and a good size for your quilt idea.
This is a great piece. Let me know how you do on finding pieces. I do know that hightechgrammy has several roads etc. Since I did her catalog, here is one link. Then click on her username and then on DBC.
This looks like a preprinted panel that you might find at Joanne's, Hancock or Wal Mart, then just add the borders and quilt it. I think if you tried to embroider this many designs it would be pretty heavy & stuff.
sorry for the duplicates...my computer is having tantrums and not playing right today...