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Comment by micromacrofoot

4 days ago

Speeding up is only the right decision because it's a poorly designed intersection.

There is no intersection design that could avoid this. Some people are going to be too close to the intersection to stop in time when they see yellow no matter what you do.

  • That's rubbish, it's provable mathematically that given any speed limit it's possible to avoid an overlapping "dilemma zone" that requires speeding up

    (v²) / (2a) ≤ (v × t_y) + L

    v = vehicle speed (meters per second)

    a = comfortable deceleration rate (meters per second squared)

    t_y = yellow light duration (seconds)

    L = length of the intersection (meters)

    You can calculate the minimum yellow time for this using t_y ≥ (v / 2a) - (L / v)

    This is rudimentary and doesn't account for reaction time, but a simple buffer would suffice.

    The failure is largely in poor planning and poor human behavior.

  • That doesn't excuse speeding up, though – if the yellow light is long enough, you will always be able to either a) safely stop with a certain given maximum deceleration, or else b) continue at your current speed and enter the intersection before the light turns red.