May I ask a question then? From the fine article it provides a list of speed limits and yellow light durations. Why do the YLDs increase with speed? It takes less time to clear an intersection if you are travelling faster, so surely a shorter yellow makes sense.
Take an extreme case (to simplify the calc. and more dramatically show how wrong this yellow light thing must be):
- 1/10th mile long intersection, and 2 speeds - 10 & 60 mph. At 10 mph it takes (1/10 / 10) or 1/100th of an hour (36 seconds) to clear the intersection. At 60 mph it takes (1/10 / 60) or 1/600th of an hour (6 seconds) to clear. A factor of SIX less time is needed to clear an intersection at 60 vs 10 mph, yet the table in TFA clearly shows yellow light times increasing with speed.
By the way, for those thinking they need a longer yellow at higher speeds for safety, this is where it has been traditional (in Canada anyway) to increase the length of time where ALL lights are red as speed goes up.
Also, FWIW, the width of the intersection _must_ be considered when setting yellow light time. The yellow light is saying "Stop if you can, but if not I will cover for you as you clear the intersection". Wider intersection == more time needed to clear it.
The full message: