If traffic signals could use data about vehicles' location and trajectory to either extend green lights by brief moments when cars are in the dilemma zone, or change to yellow early when no cars ...

The yellow light would not come into play until the 1920s. William Potts, who was a police officer in Detroit, is credited for designing the first three and four-way colored traffic lights.

Only a handful of states (probably eight) have taken the restrictive law approach. In Colorado, the state statute governing lights located outside cities and towns having their own traffic codes ...

The yellow light didn’t enter the scene until the 1920s. William Potts, who was a police officer in Detroit, is credited with designing the first three- and four-way colored traffic lights.