SigAlert: The Story Of L.A.'s Famous Traffic Alert System

"Loyd C. Sigmon, whose 'SigAlert' freeway traffic jam warning system made him perhaps the most famously unknown figure in Southern California, has died...he SigAlert tops everybody's list as one of the most distinctive aspects of L.A.'s car culture...Today, a SigAlert is issued only when one or more lanes of traffic will be blocked for at least half an hour. The term has become so familiar...that it was added to the Oxford English Dictionary a few years ago.

Thanks to Abhijeet Chavan