How Google Traffic Works

This Google Maps feature can steer you out of a jam — fast

A photograph of a traffic jam in Miami, Florida

 Wikimedia Commons / B137

Google Traffic is a feature within Google Maps that takes traffic information such as stalled vehicles, wrecks, and road construction into account and displays it as an overlay in Google Maps. This replaces your need to rely on the radio for traffic updates by giving you a simple way to view congested freeways. Google Maps can actually plot out multiple paths to your destination taking into account the most current traffic information or even predict future traffic. How exactly does Google Traffic work?

A popular theme of science fiction is that sufficiently advanced technology is indistinguishable from magic. So while Google's ability to display up-to-the-second traffic may seem like staring into a crystal ball, it is actually as simple as multiple streams of data being combined into an overall outlook.

By using this information, Google Traffic can...

  • Recognize traffic jams and rate the level of traffic going from minor traffic (green) to some congestion (yellow or orange) to a major traffic jam (red).
  • Pinpoint accidents, which are frequent causes of heavy traffic.
  • Notify of lane closures and roadway construction.

How Google Traffic Recognizes Congested Roadways

It's no great secret how the magic works. Every smartphone is capable of determining its location with an amazing degree of accuracy by combing the data from the GPS chip inside the phone with cell tower triangulation. This technique of triangulation bounces a signal to multiple cell towers to determine the location of the phone. 

Cars on the highway transmitting signals
 Wikimedia Commons

Now imagine that being done with almost every smartphone in every car on the roads and being transmitted to Google. That's a ton of data being analyzed. And that's not even the magical part. The real magic is Google's ability to process this information, weed out irregularities such as a delivery truck making frequent stops, and then present it all back to the user in real time. 

Worried about privacy? This data is regularly gathered by telecom companies like AT&T or Verizon in order to determine if you have traveled into a 'roaming' area or not. Unfortunately, it's not easy to guard against Google using this information. The only easy way to keep the information out of Google's hands is to turn off location services on your device, which means you wouldn't have access to Google Maps Navigation, either.

Google states that it doesn't store personal information such as your name or account along with the route, and the routes themselves are modified to remove start and end points, so the actual 'route' is not saved.

How Google Traffic Knows About Lane Closures and Traffic Accidents

Your smartphone isn't the only source of information used by Google Traffic. In 2013, Google bought Waze for almost a billion dollars. Waze is a popular crowdsourced traffic app where users report events such as accidents and road construction. This data is also shared with Google Maps and funneled into Google Traffic.  

In addition to Waze, Google uses data from state and local offices that oversee transportation, which increases the accuracy of lane closures and construction.

How Google Traffic Works in Your Car

Our portable little GPS machines that we keep in our pocket have become one of the most popular ways to navigate the busy streets. "Directions to Martha's house," is often the only thing we need to say to get pinpoint directions. We can even choose between multiple routes based on current traffic. 

A screenshot of Google Maps navigation
When choosing between alternative routes, the estimated travel time is based on current traffic conditions.

When you use Google Maps to navigate to a destination using an iPhone or Android smartphone, the route Google Maps determines as the fastest and most efficient at that moment is highlighted in blue. Often, there will be alternate routes highlighted in gray. Tapping one of these gray routes will make it the primary route, allowing you to choose your favorite route or simply avoid a dreaded highway.

If you use an Android smartphone, you can also activate Google Traffic hands free while driving by simply asking Google Assistant. Here are a few phrases that work with Google Traffic when paired with the "Okay Google" command:

  • "Show traffic"
  • "Hide traffic"
  • "Show accidents near me"
  • "Show alternative routes"
  • "What's my ETA?"
  • "How's traffic ahead?"
  • "How's traffic to home?"

What About Planning a Road Trip?  

Google Maps on your laptop has a really cool feature that will help you predict traffic in the future. This is great for either a road trip or simply planning out the best way to get to your doctor's appointment the next morning.  

Screenshot of Google Maps
A future few of projected traffic can help you choose the most efficient route well in advance.
  1. Navigate to in your web browser.

  2. Click the Directions button to the right of the Search Google Maps input box on the top-left of the map. The Directions button is a blue diamond with a white arrow in the middle.

  3. Fill in the starting point and the destination fields to get the directions.

  4. Just below the starting point and destination fields is a drop down menu with Leave now selected. Click this drop down and choose Depart at instead.

  5. A new field appears that lets you set the time and the date. The directions and estimated time will change based on the predicted traffic levels. You will also be able to choose from different routes based on this predicted traffic.