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Comment by codex | Hacker News Reader

How goes giving someone less time to stop before someone else goes not decrease safety? Why not shorten the yellow time to zero?

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There is a portion of time where all of the lights at the intersection are red. The person you are responding to notes that as long as this portion of time is increased such that the total time that the intersection has for someone to clear it (i.e. - time that the light is yellow plus time that the lights are all red) stays the same then safety inside the intersection should not be impacted.

This says nothing about safety leading up to the intersection (e.g. - people slamming on their brakes).

You make an excellent point.

I am worried about the case where the driver, distracted, looks away from the intersection for a second. Returning their gaze to the light, they see it red. They never observed it yellow, and thus they have no idea how long it has been red and whether or not it is safe to run the light. Perhaps this is why we have yellow to begin with--as an redundant means of clocking the time until the opposing light turns green.

If they look away long enough to miss the yellow then, some might say, they deserve what's coming.

The entire fucking point of this article is that they are dropping the time yellow is displayed too low.

If the "all-red" time is increased to compensate, then the time before someone else goes does not decrease. However, if they are just decreasing the yellow time, and keeping the all-red the same(making the total time from yellow to opposite direction green shorter) then I agree that safety has been lowered to increase profits, and this would be super un-ethical.

Even if you increase the all-red time, shorter yellows are still more dangerous. For example if you drop the yellow time too low for the legal speed limit of the road then you will create a situation where people have to start emergency braking in order to avoid running the red. This situation is unsafe for obvious reasons.

As someone pointed out it doesn't if the total red+yellow time is still the same (i.e. red time is replaced with yellow).

The counter-argument is well it increases chance of rear end collision when people stop suddenly. And that is true.

The counter-argument to the above is well they should be driving with enough assured distance between vehicles and below the speed limit.

To "maximize" revenue they could be making the legally correct assumption that everyone is keeping a good enough distance and driving below the speed limit, and they'd actually have a legally defensible position as much as I hate to admit it.

(It is also hard to argue informally that they don't know what they are doing, they know perfectly well, as others pointed out, if this was a start up maximizing revenue we should be cheering, right, right...?)

If they decrease the yellow time and increase the all-red time the same amount, people have exactly the same amount of time to stop.

Just so I understand, you are under the impression that 0 seconds is the appropriate time required to stop, which would obviously be the case if your car was moving legally at the speed limit at the edge of the road when the green light immediately changed to a red light.

Yellow means "stop if safe". Red means "stop", but when driving "if safe" is always implied. I've driven through red lights to let emergency vehicles through, and a judge would likely throw out a ticket given for such a reason.

Yellow lights increase safety by avoiding the "slam on the brakes" effect you've described. They've replaced this with a very common "floor the accelarator" reaction which also decreases safety. How do you get one without the other? Red light cameras combined with a short yellow seem the best approach to me.

Reducing the amount of time that drivers have to react will never make roads safer. The data supports this.

>Yellow lights increase safety by avoiding the "slam on the brakes" effect you've described. They've replaced this with a very common "floor the accelarator" reaction which also decreases safety.

In a typical car, flooring the gas pedal is conservatively going to be about 9ft/s² in the same direction as you're already moving. Slamming on the brakes is going to accelerate you at about 15ft/s² in the opposite direction as you're already moving. The effects these two actions have on safety are not comparable

>Red light cameras combined with a short yellow seem the best approach to me.

Except that that approach has been conclusively demonstrated to increase both accidents and fatalities, while lengthening yellow lights has been shown to reduce both accidents and fatalities.

No, you're missing his point. He's talking about safety, not avoiding fines. If lights go straight from green to red, but then wait 60 seconds before any other traffic goes from red to green, then it won't cause any safety issues, because even if a handful of cars can't stop in time when it goes red, there won't be any other traffic around. Off course it could cause problems with cars going in the same direction stopping too quickly, but the assumption is that cars won't just slam on their breaks as soon as they see the red light (and let's not forget this is also the hypothetical in which there is no orange light).

This line of discussion is unrelated to whether or not they should be trying to maximise fines.

actually, i wonder if there wouldn't be fewer rear end collisions if there were no yellow lights. people might be more cautious when approaching an intersection and less likely to ride someone's ass.

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