It even monitors, in real time, the speed of traffic flow on the roads you'll take (only in certain areas of the cities that are covered). If there's a traffic jam ahead, the system will warn you in plenty of time, and will suggest alternate routes. Not a bad way to avoid sitting in bumper-to-bumper gridlock. NavTraffic's information comes from a continuous satellite feed, supplemented by information gathered by a variety of sources, including commercial traffic data providers, departments of transportation, emergency services, cameras, and aerial traffic reports.