Synchronized traffic lights don't mean that a driver will encounter an unending number of green lights as she drives down a major road. LA's traffic system overhaul went further than most others, by using cameras and sensors to measure traffic flow and make real-time adjustments to keep traffic moving. AdvertisementAdvertisementWhy Lights Often Aren't SyncedBut retiming traffic lights costs money and manpower. A TV news report noted that the last time traffic lights were all synced in Atlanta (another city with major traffic congestion) was in the mid-1970s when Atlanta had traffic lights at 320 intersections. Retiming or syncing traffic lights is only one tool in the traffic-fighting toolbox.