He Invented the Traffic Light. They Wouldn't Buy It. Meet Garrett Morgan—the Black inventor born to formerly enslaved parents who created two life-saving inventions that changed the world. In 1912, he patented the first practical gas mask (a "safety hood"), which he used heroically in 1916 to rescue trapped workers from a poison-filled tunnel beneath Lake Erie. In 1923, he invented the three-position traffic signal—the yellow light—that's now used worldwide. But here's what history buried: fire

The other timed traffic light switch conditions (TM:PE) | Cities Skylines