We have a nifty system on many roads in The Great White North. It all started on a few roads with 80kph (50mph) limits. When an intersection light was about to turn amber, a set of bright flashing amber lights on an overhead sign about 300m before the intersection would start flashing.
If you had already gone past these lights, no problem. If you were in a position to see them flash, no problem, start coasting. The system works so well they started putting them in lower speed areas with blind corners(can't see the intersection lights). Saves brakes, and cuts down on intersection collisions dramatically.
They could sure use them in Hawaii! That state needs a lot of traffic engineering help.
