> Can someone explain me, why a shorter duration of yellow light causes more accidents? The purpose of an amber/yellow light is to give drivers a transitionary

> Can someone explain me, why a shorter duration of yellow light causes more accidents? The purpose of an amber/yellow light is to give drivers a transitionary stage. Consider the limiting case, that a light goes from green to red with no intermediate period. Drivers will not be able to avoid running red lights. They'll approach the junction at 30mph, the light will change just before they reach it, and they'll go through. Now you've normalised running red lights. Drivers can't stop if they're 5m from the red (at 30mph), but what about 30m? 50m? 100m? There's no clear cutoff. So either you make the all-red cycle really quite long, or accidents increase.