The map also contains overlays on the highways indicating the relative speed that traffic is flowing from slow (black) to fast (green). This color scheme indicates the average speed of vehicles traveling on those roads at that time.
Green indicates vehicles traveling more than 50 miles per hour. Yellow indicates speeds between 25 and 50 mph. Red means speeds are less than 25 mph. Gray means there is no data available. Black and red roads indicate traffic may be stopped at points. A yellow construction triangle means construction is causing delays.
You can make the map larger or smaller by placing your mouse pointer over the map and using your mouse wheel.