They already use arrow shapes for traffic lights (turn signals) and person/hand shapes for pedestrian crossing lights, so why not assign specific shapes to the standard traffic light? Red would be represented by an octagon shape, already established in its use for stop signs. Amber would be represented by a triangle or a diamond shape, which is often used in symbols of caution or warning. Green would still be circular. I’d like to see the red stop light being larger than the other two, to give the impression there is greater emphasis to stop than the other two. While I would like to see these implemented at every intersection, it may be worthwhile to install these only at intersections that have a high accident rate. Approaching the odd intersection equipped with different-looking lights may increase the attention of drivers. This system would assist colorblind drivers as well.