SigAlert: Celebrating the Messenger of Traffic Alerts

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

The man behind the enduring term for a traffic alert was remembered Monday during a rainy morning that might have been much more difficult on Bay Area freeways were it not for the SigAlert system he developed in Los Angeles 57 years ago.

It was radio engineer Loyd Sigmon, at Gene Autry's KMPC, who became the "Sig" in SigAlert after transmitting the first message in January 1955.

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 may 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 up and down the state 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.

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

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