Advantages: the owner can know the change of traffic light signal in real time, so as to adjust the braking and shifting efficiency in advance, and can start to pass the traffic light intersection quickly in time. The countdown traffic lights quickly let the owner enter the driving state. When there are few people at the intersection, this design is very good and improves the traffic efficiency.
Disadvantages: the countdown has time to be displayed step by step, prompting the owner that at a crowded traffic intersection, the owner may rush to the green light, which is more dangerous.
Let me give you an example from life. On the 100-meter runway, it is easier for athletes to see the countdown of10-9-8-7-6-5-4-3-2-1-0 when they enter the pre-run preparation state. I think it is the former. Athletes are more likely to get excited and think about sprinting when they have time to show it. In fact, this example is similar to the psychological state of car owners waiting at traffic lights.
This can explain why more and more traffic light intersections gradually cancel the countdown and change to non-countdown. Mainly for safety reasons, at the intersection of traffic lights, car owners can start slowly and pass safely, instead of watching the red light turn green and pulling up the speed to cross.
In addition to the above reasons, I personally think there is another reason. The design logic of countdown traffic lights is more complicated, the failure rate is relatively higher, the cost of the whole machine is higher, the electronic components are more expensive, and the non-countdown traffic lights are simpler and cheaper. Generally speaking, more and more traffic lights are changed to non-countdown.