According to the Manual of Uniform Traffic Control Devices (MUTCD), the guide that all 50 states must follow in order to create uniform travel across the country, requires that the yellow light must be one-second for every 10MPH posted for the roadway. A 45MPH road requires a minimum of a 4.5 second yellow light.
My town lowered the yellow light of it's 45MPH road to 3.5 seconds and were catching drivers left and right.
On top of that, I was conversion with my town's traffic control officer and found out the following:
The traffic lights can be changed remotely by a PC, when they were working with me to change the duration of a red light in front of my kid's school, that was causing massive backups.
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Additional information I discovered was:
1) Traffic officers can remotely change the red light, and yellow light timings any time they want.
2) They can observe a vehicle approaching, while there or by the pole mounted traffic camera, and change the light immediately.
3) They can set the traffic frequencies to a lower rate every 5th cycle, every 10th cycle, etc. so the light looks like it's fine most times but then infrequently catches a driver, then goes back to normal.
4) They can change the timings just for rush hour.
5) They can pretty do whatever they want with the timings and it may or may be logged.
6) Pretty much, they can screw with the light timings at their desire, programmatically or from their desk.
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So the only way to actually defend against these timings is to set up a video recorder on a tripod and record the light for an extended duration.
The yellow light should never fall below 1 second per 10MPH posted speed, or subset thereof.