Which person invented the stop sign, traffic circle, and the one-way street?

Considered the 'Father of traffic safety', even though he never learned to drive a car himself, the person who invented the stop sign, traffic circle and the one-way street is William Phelps Eno (1858-1945). He was an American businessman responsible for many of the earliest innovations in road safety and traffic control.

In addition to these inventions mentioned, he also is credited with the innovations of the taxi stand and the pedestrian safety islands. His rotary traffic plan was put into effect at Columbus Circle, New York City, in 1905, at the Arc de Triomphe in Paris in 1907, in Piccadilly Circus in 1926, and at the Road Point on the Champs-Elysees in Paris in 1927.

Eno graduated from Yale Univerity in 1882 where he was a member of 'Skull and Bones', an undergraduate senior secret student society.

In 1867, at the age of 9, he and his mother were caught in a traffic jam. This early childhood memory remained with him. Years later he wrote, "That very first traffic jam (many years before the motor car came into use) will always remain in my memory. There were only about a dozen horses and carriages involved, and all that was needed was a little order to keep the traffic moving. Yet nobody knew exactly what to do; neither the drivers nor the police knew anything about the control of traffic".