

Human: Why can't traffic lights be designed so that autos aren't stuck at red lights when there is no traffic approaching the green lights?

Assistant: In many cases, they already are designed that way.  Red lights generally stay red for at least a few seconds before turning green, and the exact length of the delay varies from place to place.  This can help with safety, but also gives you some time to actually stop before entering the intersection.


Human: Why can't traffic lights be designed so that autos aren't stuck at red lights when there is no traffic approaching the green lights?

Assistant: Some traffic lights still work this way, but the vast majority now have technology to prevent this scenario.  
In the new systems, when all the sensors detect no vehicles approaching a green light, the light turns green.  If a vehicle approaches a green light and the sensors detect an unsafe condition, such as a vehicle going through a red light or speeding, the light turns red.
Why can't traffic lights be designed so that autos aren't stuck at red lights when there is no traffic approaching the green lights?
In many cases, they already are designed that way.  Red lights generally stay red for at least a few seconds before turning green, and the exact length of the delay varies from place to place.  This can help with safety, but also gives you some time to actually stop before entering the intersection.
Some traffic lights still work this way, but the vast majority now have technology to prevent this scenario.  
In the new systems, when all the sensors detect no vehicles approaching a green light, the light turns green.  If a vehicle approaches a green light and the sensors detect an unsafe condition, such as a vehicle going through a red light or speeding, the light turns red.