The process of establishing night traffic control zones historically involved coordinated blackout drills during World War II, with precise timings set around twilight to optimize the effectiveness of blackouts and avoid detection by enemy forces.
The question pertains to the historical practice of setting up night traffic control zones, which were an integral part of blackout drills during air raid practices established by the Office of Civilian Defense during World War II. These drills were essential to prevent enemy forces from identifying targets by the light at night. It was therefore critical to set up or take down blackout measures precisely at times when they would be most effective, meaning possibly immediately before or after sunset or sunrise, in order to maximize darkness and minimize visibility from the air.
Historical accounts detail how the entire community, particularly in coastal regions, would partake in the blackout drills to ensure no light would be visible that might guide enemy planes during air raid situations.
This process was highly coordinated, with air raid wardens patrolling the streets to supervise compliance, signaling the start and end of the blackouts with sirens. Furthermore, optimizing the times of these blackouts might also consider civil twilight, the period when the sun is just below the horizon, resulting in only a minimal need for artificial lighting.