SigAlert is a system used by the California Highway Patrol to inform drivers of any unplanned events that result in the closure of a lane of traffic for 30 minutes or more. The system was invented in 1955 by Loyd C. Sigmon and has evolved with technology.
SigAlert is a term coined in Southern California. The California Highway Patrol (CHP) partially defines it as “any unplanned event that results in the closure of a lane of traffic for 30 minutes or more.” The word SigAlert was added to the Oxford English Dictionary in 1993, but the CHP does not recognize a specific spelling of the term. SIG Alert, SigAlert and Sigalert are used on the CHP official website.
The CHP issues a SigAlert on radio, television, or on its website. Electronic message signs found on many California highways also display these ads. Originating in Los Angeles County in 1955, SigAlerts have become common throughout the state of California.
The high volume of automobile traffic in California, combined with an extensive highway system, has resulted in a situation where even the smallest mishaps can have a significant effect on large numbers of drivers. This can result in harsh backups and cause significant delays. The SigAlert system allows real-time traffic information to be disseminated to a large audience quickly and efficiently.
Loyd C. Sigmon, known to his friends as “Sig,” invented the SigAlert in 1955, in response to problems caused by high volumes of traffic. Back then, the media would phone the Los Angeles Police Department (LAPD) to seek information on traffic accidents and delays. The Police Chief didn’t want his officers spending their time answering those questions instead of policing the streets of Los Angeles, so calls often went unanswered.
Sigmon had radio networking experience from his time in the US Signal Corps during World War II where he was in charge of non-combat radio communication. He used this experience to invent a specialized radio receiver and tape recorder system, allowing LAPD officers to call and record traffic-related messages specifically for this system. The receivers were programmed to react to a particular tone that would engage the tape to record messages. LAPD officers could leave information on the tape from where they were in the field.
Local news outlets would be alerted by a buzz or a red light on their receivers indicating that a new message had been recorded. Then they could get that message across to their audience quickly and efficiently. The system was a success and was quickly made available to a wide variety of media outlets.
The SigAlert procedure has evolved with technology and now works through web alerts, email, and other modern communication methods. SigAlert messages are still displayed on electronic highway signs and on radio and television airways. Although the name SigAlert is a tribute to its inventor Loyd Sigmon, a California joke attributes the acronym SIG to “stay in the garage.”
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