If you’re wondering how EnLighten knows when to alert you, it is because the app uses its own algorithm to calculate how much time the light has left to turn green, and also because it syncs with your city’s traffic light system. This also means that EnLighten will not work all around the world just yet. As it stands, the app will work in cities such as Portland, Oregon; Eugene, Oregon; Pasadena, California; Arcadia, California; San Jose, California; Salt Lake City, Utah; Provo, Utah; Garland, Texas and Las Vegas, with more to be added later on in the year. It sounds like a pretty clever idea and while it is nice to be alerted to when the lights turn green, to be on the safe side you should probably check the lights themselves as well to see if it matches with the app’s alerts.