Sig Alerts: What They Are and How to Use Them

Stuck in traffic again? You don't have to be

Aerial photograph showing urban highway traffic at dusk

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Finding the right route for your daily commute can make the difference between showing up relaxed and on time and showing up late with elevated blood pressure. Sig Alerts provide real-time updates on traffic conditions for cities throughout the United States.

You can use Sig Alerts on any iPhone or Android, including phones made by Samsung, Google, Huawei, Xiaomi, etc.

What Is a Sig Alert?

A Sig Alert is any event, from a collision to emergency construction, that causes unexpected delays or road closures. Traffic events and current traffic conditions are monitored and reported remotely and displayed on

One of the early systems for remote monitoring and reporting traffic was Sig Alerts. Originally called Sigmon traffic alerts after their inventor, Loyd C. "Sig" Sigmon, these alerts were used to report traffic incidents on California highways in the mid-50s.

The system debuted to mixed results; one early major use of the Sig Alert system actually caused a traffic jam by requesting medical personnel go to Union Station to assist with a derailed train, causing too many doctors and nurses to clog the roads and worsen the situation. Nevertheless, the system is now an important part of planning a trip on Los Angeles' highways, and Sig Alerts are now available in cities through the United States.

Using Sig Alerts to Plan Your Trip

Sig Alerts aren't any good if you don't get the information. The best way to use Sig Alerts is by quickly researching your planned route before you leave the house. You can find the information on the Sig Alert website, which is updated as traffic conditions change.

Screenshot of the website, showing current traffic conditions in Los Angeles

The Sig Alert website displays current traffic conditions across the chosen metro area, using red to indicate slow traffic and green to indicate normally flowing traffic. Mouse over a roadway to see that road's current traffic conditions in the sidebar.

Of course, you can find current traffic conditions near you through a variety of modern sources. So what makes Sig Alerts worth using?

First, you're getting the data directly from the source. Turn-by-turn navigation apps like Waze and Apple Maps draw information on nearby traffic from a variety of sources, including Sig Alerts. You can access this data directly through the website yourself, cutting out the middleman and ensuring the greatest accuracy.'s best feature is the enormous repository of real-time traffic cameras. Sig Alert provides access to thousands of traffic cameras scattered throughout the major cities of the United States. Select a camera icon, and you'll see an up-to-the-minute image of the current traffic conditions in that location. screenshot

The Sig Alert website will guess your location, but you can also change cities manually. Select the Settings icon, then select Change Cities to view traffic data for other locations. Real-time traffic data can currently be found on for nearly 75 major U.S. cities.

The same Sig Alert traffic information is also available through's mobile apps. Both the official Android Sig Alert app and the official iOS Sig Alert app simply display the Sig Alert website in a slightly more mobile-friendly interface. Helpfully, the apps can be launched on your Android or iOS device with the standard app-opening voice commands.

Sig Alerts are also included in other traffic sources, like navigation apps and radio reports. Those sources often draw data from the Sig Alert system.

How to Create Routes on Sig Alerts works best when you map your actual route.

Screenshot showing a created route in Los Angeles on
  1. To create a route, right-click or tap and hold on a map location, then select Start Route Here to set your origin.

  2. Right-click or tap and hold again, then select End Route Here to set your destination.

  3. Sig Alert will use traffic information near you to map the fastest route between point A and point B.

  4. Once you've created a route, you can find alternate routes by selecting Show Alts at the top of the Sig Alert window. There, you can also find traffic data for the reverse route (which can be quite different), or clear the route to start over again.

How to Save Sig Alert Routes

With a Sig Alert account, you can also save frequent routes and get proactive alerts for traffic and accidents.

  1. Select the Account icon under the Settings cog icon and select Create an Account.

  2. Once you've logged in to your account, create a new route as previously described. Then, select Save to save the route to your account. Provide a descriptive name for the route.

  3. Once you name the route, you'll have the option to set your typical drive time window and sign up for proactive email alerts about accidents and heavy traffic.