This is a recently released animation of 24 hours of traffic in Los Angeles. It’s constructed from reports sent from the smartphones of Waze users. Waze is a “social mobile application providing free turn-by-turn navigation based on the live conditions on the road and driven by users”.
It starts at 4pm but really goes beserk the next day in the AM peak. As far as I can work out, red dots are concentrations of high congestion and green dots are hazards reported by Waze users.