If You Live In LA The Term ‘SigAlert’ Is Way Too Familiar. But Why Is It Called That? (2024)

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  • How did SigAlerts begin?
  • How an early SigAlert caused traffic

There’s a term you’ve probably come across more than once while traveling around Southern California: SigAlert.

It’s one of the best ways to keep on top of traffic delays in near real-time, but they’re also a harbinger of stress. If a SigAlert is issued on your route, good luck getting to your destination on time. There could be a car stalled on the freeway, a car crash or any number of other problems shutting down lanes.

But do you know why they're called SigAlerts? They actually started out as a radio tool.

How did SigAlerts begin?

Before SigAlerts lived online in an interactive map, and were issued by the California Highway Patrol, they came from a specialized radio receiver that broadcast recorded messages.

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In the early ‘50s, civil defense officials had been looking into how to make an alert system in case of an attack from the U.S.S.R., which became the brainchild of Loyd Sigmon, executive vice president at L.A.’s KMPC radio station.

What defines a SigAlert?

  • It’s any unplanned event that causes the closing of at least one lane of traffic for 30 minutes or more, according to its website.

The system was first officially tested in November 1954. In City Hall, officials pressed a red button that took KMPC off air and instead broadcast civil defense information to listeners. Think of it like a Cold War version of the emergency alert system — the idea was to get urgent updates out fast, like potential attacks or major flooding.

A number of Southern California broadcasters signed on to install the necessary equipment, including KNX. Devices were also installed at the offices of civil defense personnel to speed up the process.

Where to find SigAlerts

  • Yes, you can look up SigAlerts and other real-time traffic information yourself by visiting SigAlert.com.

Sigmon also thought of a more daily use for the system. He approached the L.A. Police Department with an idea: set up a process for police departments to call the station when major traffic jams occur. But that wasn't really feasible for officers to do every time.

It’s unclear how many times Sigmon customized devices to use the SigAlert system in different ways, but according to SigAlert researcher Harry Marnell, for the LAPD, he used a $600 shortwave receiver and tape-recording device that booted up with a special tone. The LAPD would receive details from other agencies and then press a button to record and send that special tone with the information to radio stations (like a high-stakes telephone game).

The system, which was put into widespread use in Greater L.A. on Labor Day 1955, was intended to tell the public about a range of concerns: major freeway tie-ups, smog alerts, fire, explosions, dense fog and “atomic” attacks.

Today, it’s just about major traffic delays. Relaying of emergency information lies with things like the emergency alert system. But Sigmon has gone down in history as pioneering a way for mass communication. He died in 2004 when he was 95.

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How an early SigAlert caused traffic

Ironically, a SigAlert sort of created a big traffic jam.

Did you know?

  • Before Loyd Sigmon died, he was known to drive around in a cream-colored Lincoln Continental coupe with the vanity license plate “SIGALRT.”

  • The Santa Monica Pier’s bumper cars are also named after Sigmon’s work, dubbed Sig Alert EV. Their website says "Our Sig Alert EV is a great way to blow off steam after an hours-long commute to the west side"

In January 1956, a major train derailment happened — the Santa Fe train wreck — and an alert went out asking for any available doctors and nurses to respond. But so many people responded — including nosy onlookers — that it turned into an even bigger mess.

Priests, who were asked to come for spiritual help, were caught in traffic or turned away because of the amount of people driving over.

The derailment killed 30 people and injured 117. But the LAPD’s use of the SigAlert called into question exactly how effective (or ineffective) it was to broadcast such requests for help without a way to control the traffic build-up.

The L.A. Times put out an editorial days after the wreck that called out local authorities for poorly managing the emergency.

And while it praised how the SigAlert brought a swift medical response, the editorial board wrote that “nobody had the wit to stop” the onlookers on the highways.

What questions do you have about how L.A. works?

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If You Live In LA The Term ‘SigAlert’ Is Way Too Familiar. But Why Is It Called That? (2024)


If You Live In LA The Term ‘SigAlert’ Is Way Too Familiar. But Why Is It Called That? ›

It's any unplanned event that causes the closing of at least one lane of traffic for 30 minutes or more. How did it start? It was created in the early '50s by Loyd Sigmon, a radio executive at L. A's KMPC station.

Why is it called a Sigalert? ›

The term was originally the name of a pioneering system of automated radio broadcasts regarding traffic conditions, introduced in the 1950s and named after its inventor, Loyd Sigmon.

What does Sigalert mean in California? ›

The official Highway Patrol definition of a Sigalert is any unplanned event that causes the closing of one lane of traffic for 30 minutes or more, as opposed to a planned event like road construction, which is planned separately.

How does Sigalert work? ›

A SigAlert is a notification system used by the California Highway Patrol to alert drivers about incidents that disrupt traffic flow, typically on interstates or major roads. Whenever a freeway is closed due to a crash – that's a SigAlert.

Who owns Sigalert? ›

Sigalert.com is owned and operated by iHeartMedia. Please email Sigalert Ad Sales for rates and more information.

Why is there a net across the 52 freeway? ›

“The netting is put into place to prevent wires from potentially falling onto the road while construction work is taking place,” she told Honk in an email.

What is the Pomona freeway called? ›

SR 60. State Route 60 aka the Pomona Freeway runs parallel to the 10 from Downtown L.A. Its western terminus is the East L.A. Interchange and it travels through the south side of the San Gabriel Valley before its eastern terminus at the 10 in Riverside.

Why is there a lot of traffic in California? ›

Today, there are nearly twice as many registered vehicles in L.A. County as there are people. And, in a county covering 503 square miles, Los Angeles has about 650 miles of freeway. The many high-rise buildings that pack more office workers into relatively small spaces intensify the rush hour traffic in Los Angeles.

What is the California emergency line? ›

If you have an emergency please call 911 (24-hour, Toll free).

What time does traffic end in California? ›

Drivers traveling to and from work clog the roads between 7 a.m. and 10 a.m. during morning rush hour and between 4 p.m. and 7 p.m. in the evening. During these hours, the freeways are always jammed. Even many side streets are jammed as drivers try to avoid the bumper-to-bumper traffic of main throughways.

Is there a Sigalert app? ›

The Sigalert iPhone app is simple to use, but packed with information: *** MORE THAN JUST RED/YELLOW/GREEN - Sigalert offers incredibly detailed speed information. Sigalert's users know when traffic is moving 25 miles per hour and when it's moving 40 miles per hour.

What is the phone number for Sigalert? ›

If you need help logging in, please email support@sigalert.com or call 800-417-9152. If you do not have an account, then we do not have any personal information about you.

What is the traffic radio station in California? ›

Los Angeles, CA Traffic | 102.7 KIIS-FM.

What is the cross traffic alert warning? ›

Rear cross traffic alert monitors two areas behind you for vehicles approaching from the right or left. Rear cross traffic alert is active once the vehicle is shifted into REVERSE. When backing, you will receive a visual or auditory warning if an approaching vehicle enters the rear cross traffic alert detection areas.

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