A single vehicle probe is the latitude and longitude where a vehicle’s position is measured. This map shows the density of those counts. The colors change from dark to light as densities increase. You can see the densities at certain times by dragging the button below the video.
Internet Explorer 10+ and Microsoft Edge both have bugs that can cause flickering in this visual. Sometimes refreshing (which can be done by pressing F5) stops the flickering but it’s usually best to open this page in Google Chrome or Firefox.