(A fascinating and a clever use of shortwave radio)

Associated Press
Jun. 5, 2004 12:00 AM
LOS ANGELES - Loyd C. Sigmon, who invented the Sig- Alerts messages that
warn Southern California motorists about freeway traffic jams, died
Wednesday. He was 95 and had Parkinson's disease.

Sigmon had lived in recent years at a nursing home in Bartlesville, Okla.,
where he died.

As an executive at KMPC radio station, Sigmon invented the system in 1955,
hoping to get more listeners by broadcasting traffic information. His
device, using a tape recorder and short-wave radio receiver, was activated
by an inaudible radio tone sent out by a police dispatcher.

The receivers tape-recorded the dispatcher's emergency message, then flashed
a red light and sounded a buzzer to alert the station engineer. By pressing
a button, the engineer could broadcast the message in seconds.

The police department accepted the device on the condition that it be
available to all interested stations.

The first SigAlert was broadcast Sept. 5, 1955, and urged doctors and nurses
to respond to a train derailment outside downtown's Union Station. The
system also was used to report rabid dogs, a ship collision and the
impending collapse of the Baldwin Hills Dam in 1963.

The California Highway Patrol later took over freeway traffic duties and
handles SigAlerts, which now are computerized.

During World War II, Sigmon was head of non-combat radio communications on
Gen. Dwight D. Eisenhower's staff. Sigmon also was a partner with Gene Autry
in KMPC's parent company, Golden West Broadcasting.

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