For Los Angelinos, SigAlerts are our name for a traffic alert. They were orginally broadcasted by the LAPD starting in 1955, but are now issued via the CHP. The name "SigAlert" comes from Loyd C. Sigmon who worked and was part-owner of KMPC-AM 710 and was done in an attempt to help boost listeners. The SigAlert never made Sigmon much, if any, money, though he has received recognition and honors from local and state government agencies, the National Safety Council, and broadcasting and radio organizations
Sources
http://www.qsl.net/n6uru/sigalert.htm