Re: How many engineers does it take to change a light?
Once upon a time the Swedish lights had amber+green before green, but they had to change to comply with the Common Market. For a really clever system, badly implemented, look to Quebec, where the shape of the light can be used by the colour-blind: Square red, triangle amber, circle green. It would have been much safer to have a red circle to avoid the rest of the world's red circles being mistaken for go. Presumably zero engineers involved in that choice of light change.