Ask HN: Is speeding up to pass the Yellow traffic light an "optimum" strategy? | Hacker News Reader

Ask HN: Is speeding up to pass the Yellow traffic light an "optimum" strategy?

1 point31reasons5 comments

I think I am good driver just like any average driver but I always stop at the yellow light if I can. I in fact enjoy red lights because it helps me to relax , be in the now and get out of autopilot mode. But I see many people speed up at the yellow light to be on the "other side" and avoid the fate of waiting for a minute or more at the red light. Many times my friends complain that I don't speed up at the yellow lights.<p>So the question is, is it possible that speeding up yellow lights does not gain any time savings? that it is not the optimum strategy ? Its just our brain's impulse to prematurely optimize the task at hand ? Can it be proved mathematically if its true or false?

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  Did you see the light turn yellow?
  How long does this light stay yellow?
  Is this the first of a sequence of timed lights?
  Is the intersection photo-enforced?
  Can you enter the intersection before the light turns red?
  Will speeding up get you into the intersection
  before the light turns red, or after?
  Do you carry comprehensive insurance?
  If a collision ensues, will you be at fault?

I doubt you will find a mathematical proof that is usable in actual traffic, but a statistical approach might be usefully informative.

Have you measured the total possible minimum and maximum wait times for all light combinations over some of your usual trips? (Hint: get your friends to do the field work.) How do the "all red" and "all green" times compare proportional to the total trip time? What are the chances that waiting for one yellow light will increase the typical total trip time?

If none of that convinces you to wait for traffic lights, then take the MSF (Motorcycle Safety Foundation) course, buy a small motorcycle, and report back after a year of riding in traffic. The experience may give you a different perspective.

You probably didn't read my whole post. I don't speed up at yellow light like most people do and I don't ever intend to. What I am interested in is a theoretical insight into proving using graphs/probability theories with most simplified assumptions. I don't intend to do the field work, it could be better done with computer simulation but I am not sure if thats the better way to approach the problem. This is a theoretical question only, no MSF involvement necessary.

> So the question is, is it possible that speeding up yellow lights does not gain any time savings?

You're asking the wrong question. A better question would be, "is the risk of a collision worth the time saved?"

There's an aspect of this scenario you're not considering. If you speed into the intersection before the light turns red, you're legal, but other drivers may not realize that the fact their light is now green doesn't mean it's safe to proceed. Other aggressive drivers might jump into the intersection as soon as their light is green and collide with you. It happens regularly, whenever two aggressive drivers meet.

Driver A sees the yellow light and speeds up instead of stopping. He gets into the intersection just as the light turns red. He's legal.

Driver B sees the green and jumps into the intersection, before noticing that you're only halfway through. He's also legal.

Both drivers have acted legally, are "in the right", but both might be dead right.

I understand practical implications of all of that, but here I am interested in proving that speeding at yellow lights is not optimal strategy even in ideal (no traffic) situations in terms of reaching your destination faster.

I don't think it is, considering you might not arrive at all. The possibility of not getting there should be included in the list of outcomes. :)

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