So I got a ticket a few days ago for running a red light, the yellow light was very short, I'm trying to figure out if the city set the yellow light too short to be reasonable. The speed limit at that location is 50 mph, the yellow light is 4 seconds. Federal motor vehical safety standards specify that a vehical must be able to stop from 62 mph in 230 feet. Stopping distance = Average speed during stop x time spent stopping At constant deceleration average speed during stop = 1/2 initial speed 62 mph = 91 fps so... 230=(1/2)*91*t 230=45.5*t t=5 seconds Stopping from 50 mph instead of 62 should take 50/62 of the time, or 4 seconds. This is exactly the duration of the yellow light so stopping in time would require instant reaction to the light turning yellow. Instant reaction is impossible for a human so the light is unreasonably short. On the other hand... 50 mph = 73 1/3 fps 73 1/3 fps * 4 seconds = 293 1/3 feet so I should have been at least that far from the light when it turned yellow. Since my stopping distance from 50 mph is shorter then my stopping distance from 62 mph I should have had > 63 feet to react to the light. I don't see a flaw in either line of reasoning but they obviously contradict each other. Where is my error?