SigAlert: Celebrating the Messenger of LA Traffic Alerts

Nearly 60 years after the alert system was developed, SigAlert is one of the most-Googled terms in LA

Drivers use various colorful terms to describe traffic in Los Angeles, especially when they're stuck in conditions like Monday's rainy commute, but one term has endured when it comes to alerting motorists to freeway headaches -- SigAlert.

It was radio engineer Loyd Sigmon, at Gene Autry's KMPC, who became the "Sig" in SigAlert after developing the system in 1955. The first messages were broadcast later that year.

At the time, the alerts were used for more than just freeway closure information. One of the first major alerts involved a call for doctors and nurses needed after a train wrecked near Union Station.

"When they had the SigAlert put out, it actually created more traffic than it relieved because people were rushing out to see the train accident right by Union Station," said Caltrans District 7 Director Mike Miles. "They put out an alert for doctors and nurses to respond. So many responded, it created a lot more traffic."

Sigmon's receiver picked up the LAPD alerts and triggered reports on commercial radio stations. Dispatchers transmitted a radio tone that was picked up by SigAlert receivers at radio stations.

"Chief William Parker agreed to use the technology, but only if KMPC agreed to share it with other outlets," said Councilman Tom LaBonge, who is pictured with Sigmon (right).

The receivers tape-recorded the bulletin and notified the station engineer, who could broadcast the message to listeners.

The California Highway Patrol now uses the term to alert motorists to "any unplanned event that causes the closing of one lane of traffic for 30 minutes or more."

"It's something that's done a lot to keep the citizens moving," said CHP Assistant Chief Calvin Aubrey. "It saves a lot of money in lost wages from people being stuck in traffic."

As a testament to the timeless SigAlert, it was one of LA's most-Googled search terms of 2011.

Matt Roth, of Automobile Club of Southern California, called the SigAlert "one of the key bits of information that helps the automobile fit into our society."

"That's really what Los Angeles and California have meant to the world when it comes to transportation," said Roth.

Sigmon, an engineer in the U.S. Army during World War II, died in 2004.

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