# Yellow Light Duration

Discussion in 'Math' started by tracecom, Sep 2, 2014.

1. ### tracecom Thread Starter AAC Fanatic!

Apr 16, 2010
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In the attached formula for yellow light duration, what is the duration of a yellow light in a 45mph section of road (assuming it's level?) I calculate 1.78 seconds, but surely that can't be correct.

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Nov 30, 2010
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3. ### studiot AAC Fanatic!

Nov 9, 2007
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Before commenting I would be grateful if someone would clarify the driving rules in relation to traffic signals in the US, in case they are different from those in the UK.
Note that those in European countries differ.

4. ### crutschow Expert

Mar 14, 2008
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45MPH is 66 ft/s so I calculate 1 + 66/20 = 4.2s.

5. ### tracecom Thread Starter AAC Fanatic!

Apr 16, 2010
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Okay, I think I see how you are using the formula, but shouldn't the answer be 4.3 seconds? Thanks.

6. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Basically, the rules are green is go, yellow is stop unless it is not safe to do so (you are too close to the intersection) and red is an absolute stop.

As with any conditional rule, yellow suffers from the interpretation of what is too close. This drivers education link describes in detail what is the proper response. Note this differs from the popular US interpretation that yellow means "drive like h€|| before it turns red."

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7. ### studiot AAC Fanatic!

Nov 9, 2007
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Thank you djsfantasi for the information and the link.

Interestingly the link also showed me to another page on that website that suggested in parts of the US it can be legal to turn left on Red.

http://www.driversedguru.com/driving-articles/drivers-ed-extras/can-you-make-a-left-turn-on-red/

This is also legal in parts of Europe, but not in the UK.

Very confusing, especially for pedestrians that happen to be crossing.

It is not clear from the links what the colour sequence is on the US, but in the UK the amber (yellow) colour appears twice in the sequence, and has a different meaning in each apprarance.
However the rules appear similar.

Last edited: Sep 3, 2014
8. ### Wendy Moderator

Mar 24, 2008
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Texas has some of the most dangerous cities in the US to be a pedestrian. It doesn't help some of them are not too bright either. Right turn on red is the norm unless otherwise posted here. I guess you are either quick or dead.

9. ### crutschow Expert

Mar 14, 2008
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Yup. Somehow I slipped a digit.

10. ### Wendy Moderator

Mar 24, 2008
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You gave someone the finger?

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11. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Found this to support my previous comment

Nov 23, 2012
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13. ### wayneh Expert

Sep 9, 2010
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In Chicago also. Huge scandal. The gist of it is that revenue from the traffic camera or red light tickets is a function of the yellow time. If the yellow timing adheres to federal standards, the revenue doesn't justify installing the camera. Only by shortening the yellow can you goose up ticket revenues. And of course in Chicago, that all means that somebody's cousin got a nice check to look the other way.

14. ### #12 Expert

Nov 30, 2010
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Experiments in Florida have shown that if the yellow light is extended by 1/2 second, camera tickets are reduced by 90%. So, what did they do? Take 1/2 second off the time of the yellow light and, as I call it, "milk the herd". Channel 10 News has made a lot of headlines with this and corrected some of the malfeasance.

On the other hand, I've lived in Chicago and do not expect any amount of publicity will affect this highway robbery of the citizens in that city.

15. ### wayneh Expert

Sep 9, 2010
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Believe it or not, this one has reached a tipping point even for Chicago. The city may end up paying back millions of dollars collected in fraudulent fines. The Tribune has been researching the facts of the fiasco and in so doing, leading the charge against it.

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16. ### tracecom Thread Starter AAC Fanatic!

Apr 16, 2010
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As you may have guessed, I (actually my wife) was recently a victim of one of these short yellow lights in a small town south of here. I went back there earlier this week and timed the yellow; it's 4.1 seconds, and according to the ITE, it should be at least 4.3 seconds. I say, "at least" because it's slightly downhill in the direction she was traveling, but I don't know the actual grade and cannot include that in the ITE formula. The next closest light to the one she ran is about 1/2 mile away, and the yellow is 4.8 seconds.

I would like to take it to court, but if I do, and lose, I pay not only the \$50 fine, but and additional \$88 in kangaroo court costs.

17. ### studiot AAC Fanatic!

Nov 9, 2007
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(4.3 - 4.1) is 0.2 seconds or 5%.

Can you measure the light timing to that accuracy and prove it?

Is there any margin for light timing error in the formula and is 5% within it?

18. ### tracecom Thread Starter AAC Fanatic!

Apr 16, 2010
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I probably won't go to court. It's just one of those unfair situations in life that are relatively unimportant individually, but lead to greater and greater erosion of individual rights. Someone should stand up to them, but most take the easy way out, and pay the \$50.

19. ### wayneh Expert

Sep 9, 2010
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I'd ask a local lawyer for an off-the-cuff (free) opinion. Unless the judge is in on the scam and is well aware of the issue, just raising it in your defense might get you off. There may not be anyone in the courtroom able to rebut your defense, and the judge would have little choice. But in Chicago for instance, before the scandal rose the current level, you essentially could not challenge the red-light tickets. They weren't interested in your story, just your payment.

Only a local lawyer would know which way the winds are blowing on your area. Try it. They're more willing to talk than most people think. I got some great free advice not long ago.

20. ### Wendy Moderator

Mar 24, 2008
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A couple of years ago I got a ticket for no seatbelt. I would normally just pay it, but the fine was \$210 dollars. I took a chance, hired a lawyer for \$30, and he got me off.

Not proud of it, but the fine was not justified by the offense.