Loyd C. Sigmon

Loyd C. Sigmon, who invented the system known as SigAlerts that warns Southern California motorists of freeway traffic jams, has died. He was 95.

Mr. Sigmon died Wednesday after a long illness at a nursing home in Bartlesville, Okla., head nurse Barbara Harper said.

Mr. Sigmon, who had Parkinson ' s disease, had been at the facility for four years.

In 1955, Mr. Sigmon invented a system that allowed Los Angeles police to issue emergency warnings to local radio stations. At the time, he was an executive for radio station KMPC and wanted to boost ratings by providing traffic information.

Mr. Sigmon developed a $600 device that used a tape recorder and shortwave radio receiver that allowed a police dispatcher to activate it using a special tone, then record a message that could be broadcast. A red light and sometimes a buzzer alerted the radio station engineer that a message was ready.

Los Angeles Police Chief William Parker accepted the device on condition it be available to all interested radio stations. Parker also is reputed to have dubbed the bulletins SigAlerts, a term that became commonplace.

The first SigAlert was broadcast Sept. 5, 1955, by six radio stations. It urged doctors and nurses to respond to a train derailment outside Union Station in downtown Los Angeles. The system also was used to report rabid dogs, a ship collision, a pharmacist ' s potentially fatal error in filling a prescription and the impending collapse of the Baldwin Hills Dam in 1963.

The SigAlert was Mr. Sigmon ' s claim to fame. He was honored by governments, broadcasting organizations and the National Safety Council. He had personalized license plates that said SIGALRT.

" I ' m proud of the fact that the SigAlert system made a contribution, " Mr. Sigmon once said. " I never tried to make any money off it. In fact, I lost some because I used to bet on a horse named SigAlert that never won. "

The California Highway Patrol later took over freeway traffic duties from the Los Angeles Police Department and handles SigAlerts, which are computerized. SigAlerts are limited by the CHP to an unplanned event that causes the closing of one lane of traffic for 30 minutes or more.

Mr. Sigmon was born in 1909 to a cattle-ranching family in Stigler, Okla. He was fascinated by electronics and got his amateur radio license at 14.

In 1941, after helping to build a radio station in Kansas City, he joined KMPC-AM as an engineer and became a partner with Gene Autry in KMPC ' s parent company, Golden West Broadcasting.

During World War II, he was on Gen. Dwight Eisenhower ' s staff as head of noncombat radio communications in the European theater.

After the war, he returned to Golden West and became an executive vice president. He retired in 1969. In the late 1990s, he moved to Oklahoma to be near his family.