Art Lebedev Studios has posed an interesting yet not bad idea:
Why not make traffic lights square?
We’re used to round lamps in traffic lights. As drivers, and I know this to be true in other countries, we don’t always pay attention to the round red and green things telling us when to gas and brake. Art’s concept is centered around making the traffic lights more visible, more present. LED of course, and as a square, there’s more light-per-surface area. Check out these images: