what do the different colors of the trip mean on the map (red, green, orange)

Speed (sadly it's a pretty inaccurate because it's the speed at the time moment the API is called and that's only happening once a minute)

Is the color is based on polled vehicle speed vs. posted speed limit?
i.e. Green is at or under the speed limit
Red is way over the speed limit?
Orange is somewhere in between?