Sig Alert

Sig alert, Sig-alert or Sigalert in California, as well as other parts of the United States, means an incident that significantly disrupts road traffic. The term was originally the name of a pioneering system of automated radio broadcasts regarding traffic conditions, introduced in the 1950s and named after its inventor, Loyd Sigmon.

A Sigalert 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".[1][2] In practice, the term refers to a notice of such a closure issued by the CHP, and Sigalerts are posted on the CHP website, broadcast on radio and television stations throughout California, and signaled to motorists via electronic message signs on the freeways. The California Department of Transportation (Caltrans) defines it as any traffic incident that will tie up two or more lanes of a freeway for two or more hours.[3]

The term was added in 1993 to the New Shorter Oxford English Dictionary. In practice, there is no standard spelling; the CHP website uses "SIG Alerts"[4] and "Sigalert"[1] while Caltrans uses "Sig-Alert".[3]

  1. ^ "Sigalert.com - Frequently Asked Questions". Archived from the original on 2015-04-15. Retrieved 2017-04-19.
  2. ^ a b "Q. What are Sig-Alerts?". CalTrans FAQs. Retrieved 2017-04-19.
  3. ^ Cite error: The named reference cad was invoked but never defined (see the help page).