SigAlert

A Sig Alert is defined by the California Highway Patrol (CHP) as "any unplanned event that causes the closing of one lane of traffic for 30 minutes or more".CalTrans uses the term "SigAlert", and is defined as any traffic incident that will tie up two or more lanes of a freeway for two or more hours. Sig Alerts are issued by the CHP and are posted on their website, broadcast on radio and television stations throughout California, and signaled to motorists via electronic message signs on the freeways. The term was added in 1993 to the New Shorter Oxford English Dictionary. In practice, there is no standard spelling; the CHP Web site uses "SIG Alerts" and "Sigalert" while the California DOT uses "Sig-Alert".

SigAlerts originated in 1955 with the Los Angeles Police Department (LAPD). By the early 1950s, the rapidly growing number of automobiles in Los Angeles had greatly increased the frequency and severity of traffic accidents and jams. Radio stations reported traffic conditions, but the LAPD refused to call radio stations with this information, so each station would call the LAPD, a process that tied up telephone lines and forced officers to repeat the same information again and again.

In 1955, Loyd C. "Sig" Sigmon began developing a solution. Sigmon was executive vice president of Golden West Broadcasters (a company owned by singing cowboy Gene Autry). Sigmon had worked for Golden West's station KMPC 710 in 1941, but found himself in the United States Army Signal Corps during World War II, assigned to General Dwight D. Eisenhower's staff, in charge of non-combat radio communications in the European theater. Now, he proposed to apply his knowledge of complex radio networks to the situation in Los Angeles.

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