Wireless!? On traffic lights that presumably have to be connected to a power source anyway? It seems to me that the cost of running an additional network cable to each light (or even just sending the control through powerline networking) would be negligible, and it would prevent much of the attacks described - physical "hacking" would be required, which is more difficult to do and easier to detect. This seems like yet another case of large increases in complexity (and thus attack area) for little to no benefit, as is all too common in systems these days.