What specific element did Dr. John Harriss's experimental signal in New York City feature, leading to a system where pedestrians could cross diagonally?

Answer

An illuminated hand facing outward

Dr. Harriss tested a signal featuring an illuminated hand, and his system introduced a multi-period cycle that stopped all vehicular traffic, allowing pedestrians to cross in all directions, including diagonally (known as the 'scramble').

What specific element did Dr. John Harriss's experimental signal in New York City feature, leading to a system where pedestrians could cross diagonally?
inventionSafetySignaltrafficcrosswalk