Some combination of the speed of the cars around you, the speed limit gleaned from posted signs, the speed listed for the road in the GPS map, and the average s

Some combination of the speed of the cars around you, the speed limit gleaned from posted signs, the speed listed for the road in the GPS map, and the average speed of cars when traffic is within a density range[1] would work. The reason for using a density range, is that if the cars are too dense, there is likely traffic, and if they're not dense enough, you'll either have outliers skewing the data, or people driving faster than normal, due to the lack of other cars. [1] When you're using Google Maps, google crowdsources data on how fast traffic is moving, based on all devices using Maps in that viscinity. You can infer traffic density based on sampling the number of people in a given area providing data. I assume that this data would only get more granular as time goes on, as we add crowdsourced data from autonomous vehicles as well. https://googleblog.blogspot.com/2009/08/bright-side-of-sitting-in-traffic.html https://googleblog.blogspot.com/2009/08/bright-side-of-sitti...