Re:Researchers find it’s easy to hack traffic lights
by ams6110 on Wednesday August 20, 2014 @06:36PM
(#8205052)
The controllers may be able to order it but the lights are supposed to be wired so it's impossible. E.g. grounding the green lights thorugh the cross direction green lights so you can't illuminate green in all directions at once. Or something along those lines.
edit: s/opposite/cross/