Quote:
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Originally Posted by sblime42
Table 4D-102 Minimum Yellow Light Change Interval
Posted Speed or Prima Facie Speed Minimum Yellow Interval
MPH / SECONDS
25 or less / 3.0
30 / 3.2
35 / 3.6
40 / 3.9
45 / 4.3
50 / 4.7
55 / 5.0
60 / 5.4
65 / 5.8
Seems they are related to how fast the posted speed is. Again, these supposedly only apply to lights with cameras on them. I do not believe this law applies to regular lights.
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If I had to guess why those times were picked, I would put a few bucks on my theory that it's the amount of time it took a test vehicle to come to a full stop from the posted speed limit when the law was written, plus ten or twenty percent for a margin of safety.
I've started to pay attention to the solid white lines that lead up to a multi-lane intersection from the dotted line, and the line is about 1.25 times the distance it takes me to comfortable come to a stop from the posted speed limit. I have yet to cross the white line as a light turns yellow, but I suspect that braking time from the end of the white line corresponds to the yellow light duration.