January 22

1956:  KMPC broadcasts one of the very first “SigAlerts.”

Former U.S Army Signal Corps engineer Lloyd C. ‘Sig’ Sigmon (1909-2004), working for Gene Autry’s KMPC Radio, had developed a specialized radio receiver and reel-to-reel tape recorder that records Los Angeles Police Department dispatch information on traffic-accidents.  The information is then broadcast to steer listeners around accidents.

The first SigAlert is attributed to Labor Day Weekend, 1955, but many stories erroneously place the birth date as January 22, 1955.

This incident, in 1956, is one of the first major “Sigmon traffic alerts” actually causing its own traffic jam.

The alert described the derailment of a passenger train near Los Angeles’ Union Station and requested any available doctors and nurses to respond to the scene. Too many doctors, nurses, and sightseers drove there, making the situation worse.

Today SigAlert is used by Caltrans throughout California and is defined as “any unplanned event that causes the closing of one lane of traffic for 30 minutes or more.”

In 1998, when Caltrans and the California Highway Patrol opens their Freeway Traffic Center in Los Angeles, Sigmon attends as their special Guest of Honor.

“SigAlert” does not have a standardized spelling. Caltrans has used “SIG Alert,” “SigAlert,” and “Sigalert” over the years.

In 1993, the term was added to the Oxford English Dictionary.