Google maps has been showing traffic on major highways for over a year now. With this information, you tell Google when you'll be traveling and they will adjust your travel time, or route, to account for traffic. Google has recently updated this feature so that now they are including traffic on side roads too. If you live in a metropolitan area, you know this traffic can be bad. So having this information available in Google maps can really help you come up with the best route for your trip.