How Does Live Traffic on GPS Work?

By Milton Kazmeyer

GPS with live traffic updates can route you around slowdowns.
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Any GPS navigator can help you find the quickest route to your destination, but some higher-end models offer additional features that come in handy. One such option is live traffic updates, which give you the ability to route around accidents and slowdowns before you are stuck in bumper-to-bumper traffic. Depending on your GPS model, you may need additional hardware or a service membership before you can take advantage of traffic updates.


The traffic information provided to your GPS navigator comes from a variety of sources. Companies combine Department of Transportation sensor data, reports from trucking companies and shipping services, and live traffic updates from radio and TV news observers to create a real-time model of the current traffic flow. The services combine this data to estimate delays for commuters taking common routes. They can even pinpoint where traffic snarls begin and end.

FM Traffic

If your GPS has live traffic via FM, you will need to connect the unit’s antenna to receive updates. Commonly, the antenna is part of the power connector, but it may also be a separate unit. Once the antenna is connected, your GPS will receive a special sideband signal from nearby FM towers that transmit real-time traffic updates. Typically, FM traffic updates are less detailed than other sources of live-traffic data, but FM updates are free for anyone who has the proper receiver.

Cellular Updates

In addition to an FM receiver, some GPSs include a cellular modem that accesses premium services. These units receive detailed traffic updates directly from the manufacturer. They also transmit information about your current travel conditions that is used to refine the system’s delay estimates. If multiple GPS units indicate their users are slowing, it could be a sign that traffic is backing up and delay times are increasing. Typically, these services require a monthly or yearly fee. They may also provide weather, gas prices, and other real-time information.


GPS models handle traffic rerouting in various ways. When some GPSs detect a traffic jam ahead, they pop up a warning and allow you to press a button to route around the blockage. Other models automatically incorporate these traffic updates in their directions, plotting and comparing different routes to ensure you remain on the fastest and most-direct path to your destination. In either case, your GPS continues to receive and analyze updates for nearby routes, constantly working to ensure the optimal route to your destination.