There was a book, by Moorcock I think, in which road users became part of a culling operation in which all the tunnels under the Thames were instantly and randomly closed north and south and anyone therein slaughtered. Now that’s not really specific enough for us. Am sure that software in traffic cam’s could ID cyclists. How about putting them on traffic lights and one-way streets and linking to remote 50 cal mini guns. Break the rules and… well, you get the idea.