The app’s interface is as simple -- and deliberately boring and non-distracting -- as it can be. A red, yellow, or green circle indicates the current state of the signal. A countdown pops up at the bottom of the circle, letting the driver know how long before the green light goes red and then how you'll have to wait at the red light. “Knowing how long the light will be red makes it seems shorter,” Ginsberg said. “You feel like you are controlling it. You aren’t.” A chime sounds five seconds before the light turns green again, alerting the driver that whatever song he’s cued up on Spotify will have to do at least until the next red light.