I've lived in Southern California for nine years and have heard many times in traffic reports the term "sig alert." I know that this means you're screwed if you're driving anywhere, but I can't figure out what the heck "sig" stands for.
-- Bob Ternansky, on the road
Can't believe we've never answered this one. Lloyd "Sig" Sigmon was a broadcast engineer and eventually co-owner (with Gene Autry) of radio station KMPC in Los Angeles. He developed a system by which LAPD dispatchers could send a signal tone to each local radio station, the tone would activate a special tape recorder, then the police would record a message detailing the problem, and the tape could be replayed on the air. The first Sig Alert was broadcast on September 5, 1955. Not long after, one of the broadcasts actually caused a traffic jam. It was a call for doctors and nurses to assist at the scene of a train derailment in downtown L.A. Early on, the system also broadcast such announcements as rabid-dog alerts, gas leaks, an impending dam collapse, and a message from a pharmacist who had made a potentially deadly mistake in filling a prescription. The LAPD's Chief Parker actually coined the term "Sig Alert."