Here was how I imagined traffic lights worked: Pressure-sensitive plates were placed directly beneath the asphalt on all the roads. When too many cars drove over them, indicating that traffic was getting too heavy on a particular road and wildly rushing cars were more likely to crash into each other, the light turned red to stop all the cars and make their drivers calm down. Then the cars on the other road, their drivers nicely calmed down, could proceed until they, too, became disorderly and the pressure plates told the light to change.