Length of yellow caution traffic lights could prevent accidents: study

 

A couple of years ago, Hesham Rakha misjudged a yellow traffic light and entered an intersection just as the light turned red. A police officer handed him a ticket.

"If the yellow time is not set correctly, a dilemma zone is imminent," Rakha said. "The dilemma zone occurs when the driver has no feasible choice," he said. "In other words the driver can neither stop nor proceed through the intersection before the light turns red. This can also occur if the approaching vehicle is traveling faster than the posted speed limit and/or if the driver's perception and reaction time is longer than the design one-second value."

People over 60 years of age have a longer perception-reaction time, so they have to brake harder to stop. But they are more likely to try to stop, compared to younger drivers. However, if they keep going, they are unlikely to clear the intersection, the researchers report.

Read more at: http://phys.org/news/2012-09-length-yellow-caution-traffic-a...

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"In order to be old and wise, one first must have been young and stupid."

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This can be avoided by a concept where lights are red in all directions for several seconds.

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*Keith* MacBook Pro *wifi iPad(2012) w/BadElf GPS & iPhone6 + Navigon*

I wonder ...

kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

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Nuvi 2460

4 way red lights

When a traffic light was installed near Ferris High School in Spokane, the light was red in all directions for about 3 seconds. I suspect that it was because there was not room for lefthand turn lanes, although many motorists were turning left. The delay cleared the intersection before a green light appeared. I believe the delay was implemented elsewhere but I can't remember specific places.

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1490LMT 1450LMT 295w

Here in Chattanooga

tomkk wrote:
kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

This is how our signals work.

I have seen this regularly

tomkk wrote:
kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

I have seen it around, but it is unfortunate when my light turns green, I still have to wait for the red-light runners....

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Streetpilot C340 Nuvi 2595 LMT

Agreed!

shrifty wrote:
tomkk wrote:
kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

I have seen it around, but it is unfortunate when my light turns green, I still have to wait for the red-light runners....

Agreed! I'll look for the red light runner first when my light turn green.

Replace The Walk/Don't Walk Pedestrain Signal..

I have seen some of the older style pedestrian walk/don't walk signals replaced by count down timers that tells in seconds how long before the light is going to change.

This helps greatly because one can easily judge if there's still enough time to cross the intersection, or if one should prepare to stop.

Granted it won't prevent drivers who are going to run the red no matter what, but for a good portion of the driving public it helps to eliminate that point as you enter the no man's land zone.

Nuvi1300WTGPS

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I'm not really lost.... just temporarily misplaced!

Prepare to stop

Isn't that the whole purpose of the yellow light in the first place? If the light is yellow, you stop if it is safe an practical to do so. Doesn't matter if the light turned yellow 100 seconds or 100 milliseconds ago. If it is yellow, you stop if you (practically and safely) can. Why is any additional info needed?

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-Quest, Nuvi 1390T

I agree. I like the system

I agree. I like the system in place. I think just too many people try to beat the yellow caution light.

Yellow

In the city where I live it seems that to many people Yellow means step on the gas and go like hell. In fact I see many even going through red lights, which have already been red for a couple of seconds.

I think its like this all over North America!

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Nuvi 350 long gone, Nuvi 855LMT, Nuvi 2797LMT, 3790LMT passed on to my daughter. Using Windows 10

I like the countdown timers

we have Ped control lights with a large count down timer(about 15 seconds). I use them more then the yellow light where they have them. Bet the cut down on RLC revenue also.

But it's contrary to the

But isn't it contrary to the money raising purpose of a red light camera?

That's just my paranoia talking. But it's good to be paranoid when I know they're out to get me.

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nüvi 750 & 760

Yup

Melaqueman wrote:

In fact I see many even going through red lights, which have already been red for a couple of seconds.

I think its like this all over North America!

When I first moved back to the Moline IL area, I was in the left-hand turn lane, moving right along, when the yellow light appeared. As I lifted, my passengers all screamed, "DON'T STOP." I kept going and did pass the crosswalk just as the light went red. I looked in my mirror and saw 3 more cars follow me. WTF! They explained, "Because it is the oncoming traffic that get the green next, they can clearly see you, and will wait for you to clear."
WOW. And they were/are correct.

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1490LMT 1450LMT 295w

Yellow Vs. Red

ddeerrff wrote:

Isn't that the whole purpose of the yellow light in the first place? If the light is yellow, you stop if it is safe an practical to do so. Doesn't matter if the light turned yellow 100 seconds or 100 milliseconds ago. If it is yellow, you stop if you (practically and safely) can. Why is any additional info needed?

Yellow does not mean stop, red does. At least where I come from.

technically

twix wrote:
ddeerrff wrote:

Isn't that the whole purpose of the yellow light in the first place? If the light is yellow, you stop if it is safe an practical to do so. Doesn't matter if the light turned yellow 100 seconds or 100 milliseconds ago. If it is yellow, you stop if you (practically and safely) can. Why is any additional info needed?

Yellow does not mean stop, red does. At least where I come from.

Technically you are correct. According to the Illinois Driver Handbook "Yellow light — The yellow light warns that the signal is changing from
green to red. When the red light appears, you may not enter the intersection." (pg.72)

But that isn't what ddeerrff was saying was it?

--
"In order to be old and wise, one first must have been young and stupid."

How many seconds is the

How many seconds is the yellow light anyway? Does it vary by state? Slamming on the breaks and stopping is just as dangerous if not more because cars behind you are not expecting that. It's just not realistic to think people are going to drive like that. Good like trying it - you'll be rear-ended in no time.

should be standard

ptownoddy wrote:

How many seconds is the yellow light anyway? Does it vary by state? Slamming on the breaks and stopping is just as dangerous if not more because cars behind you are not expecting that. It's just not realistic to think people are going to drive like that. Good like trying it - you'll be rear-ended in no time.

The yellow light interval should vary depending on the allowable speed of the road on which the vehicle is traveling. There are other factors, of course, including line of sight, slope of the roadway, etc.

Most states use formula from the Institute of Traffic Engineers (ITE).

here is a link to a good article
http://www.cga.ct.gov/2012/rpt/2012-R-0219.htm

Look especially at the last two paragraphs to answer your by state question.

interpretations based on where you come from

twix wrote:

Yellow vs. Red
...
Yellow does not mean stop, red does. At least where I come from.

Take a look at the last two paragraphs of this article

http://www.cga.ct.gov/2012/rpt/2012-R-0219.htm

This is done in Canada

kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

Done in Canada. I could not believe the light changing when I was visiting my friend in Chicago. Once the light changed, it was IMMEDIATELY Green for the opposing traffic. Scary stuff when you are a pedestrian walking.

Longer Yellow prevent accidents and decrease revenues

What is more important is safety or revenue. For drivers safety is better longer yellow to give time to clear the area and not be afraid getting a ticket. For the city, longer yellow is better because they have safer traffic on the streets and traffic flow much smooth. on the other side shorter yellow can be a source of revenue to the city, but drivers are going to be frustrated and clog the courts to contest the fines.

I think every person likes to live in a safe city not be afraid crossing the intersection.

Studies have prove that increasing the yellow is the way to go.
It is sad that cities put their citizens in danger to raise revenue.

Not as clear as most believe

Icedog wrote:

...
For the city, longer yellow is better because they have safer traffic on the streets and traffic flow much smooth.
...
Studies have prove that increasing the yellow is the way to go. It is sad that cities put their citizens in danger to raise revenue.

Up to a certain point, increasing yellow intervals does increase safety. Above that point, safety may decrease.

Please read this article
http://www.washingtonpost.com/wp-dyn/content/article/2010/06...

All way red

tomkk wrote:
kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

All of the lights around here are red all ways before the green. Now that everyone knows it the red light runners count on it, so it solved nothing.

which is why

avandyke wrote:
tomkk wrote:
kch50428 wrote:

This can be avoided by a concept where lights are red in all directions for several seconds.

I wonder if anybody's tried this, I haven't seen it anywhere. Wouldn't take but a second or two to achieve the effect.

All of the lights around here are red all ways before the green. Now that everyone knows it the red light runners count on it, so it solved nothing.

Which is why artificially lengthening the yellow time only works for a short period. Drivers learn about the "long yellow" and feel they have more time to run the light.

--
"In order to be old and wise, one first must have been young and stupid."

O.K., I'll Explain It So You Can Understand..!

ddeerrff wrote:

Isn't that the whole purpose of the yellow light in the first place? If the light is yellow, you stop if it is safe an practical to do so. Doesn't matter if the light turned yellow 100 seconds or 100 milliseconds ago. If it is yellow, you stop if you (practically and safely) can. Why is any additional info needed?

1.) You're approaching a intersection where the light is green.. and at some time in the future (of which you're unable to determine at that precise moment), the light will turn to yellow.

2.) You look over to the right at the pedestrian walk/don't walk signal and see a countdown timer which is showing a number.

3.) You know that number corresponds to the amount of seconds that are left before the green signal turns to yellow.

4.) Because of your driving experience, you're able to determine (via the vehicles existing speed, distance to the intersection and time in seconds shown on the countdown timer), whether or not you're able to safely continue through the intersection.. or if you should start to slow down and prepare to stop because the light will have turned from green to caution yellow and then to red before you can safely go through the intersection.

So to answer your question of.. "Why is any additional info needed?" Because traffic engineers have determined that the pedestrian countdown timers reduce not only crossing injuries, but red light incidents also.

I hope the above helps to clear up the confusion you had.

Nuvi1300WTGPS

--
I'm not really lost.... just temporarily misplaced!

you're shooting yourself

Nuvi1300WTGPS wrote:
ddeerrff wrote:

Isn't that the whole purpose of the yellow light in the first place? If the light is yellow, you stop if it is safe an practical to do so. Doesn't matter if the light turned yellow 100 seconds or 100 milliseconds ago. If it is yellow, you stop if you (practically and safely) can. Why is any additional info needed?

1.) You're approaching a intersection where the light is green.. and at some time in the future (of which you're unable to determine at that precise moment), the light will turn to yellow.

2.) You look over to the right at the pedestrian walk/don't walk signal and see a countdown timer which is showing a number.

3.) You know that number corresponds to the amount of seconds that are left before the green signal turns to yellow.

4.) Because of your driving experience, you're able to determine (via the vehicles existing speed, distance to the intersection and time in seconds shown on the countdown timer), whether or not you're able to safely continue through the intersection.. or if you should start to slow down and prepare to stop because the light will have turned from green to caution yellow and then to red before you can safely go through the intersection.

So to answer your question of.. "Why is any additional info needed?" Because traffic engineers have determined that the pedestrian countdown timers reduce not only crossing injuries, but red light incidents also.

I hope the above helps to clear up the confusion you had.

Nuvi1300WTGPS

You're shooting yourself in the foot. Your item 1 states you have no idea when the light will change, but then BANG. Item 2 states there is a countdown timer.

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"In order to be old and wise, one first must have been young and stupid."

I do all the time

ptownoddy wrote:

How many seconds is the yellow light anyway? Does it vary by state? Slamming on the breaks and stopping is just as dangerous if not more because cars behind you are not expecting that. It's just not realistic to think people are going to drive like that. Good like trying it - you'll be rear-ended in no time.

Yellow lights tend to vary greatly around the country, I've seen as little as about 2 seconds, up to around 10 or so. I actually stopped a yellow for about 4 or 5 seconds, thought the light was broken, and then began to proceed through the intersection. It turned red a short time later. Way too excessive in my opinion.

I stop on yellow all the time, no matter how excessive I need to brake. Drive about 50K a year throughout the country (and Canada), so far no issues. I'll take my chances.

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Streetpilot C340 Nuvi 2595 LMT

I Should Proof Read To Catch My Mistakes..

Box Car wrote:

You're shooting yourself in the foot. Your item 1 states you have no idea when the light will change, but then BANG. Item 2 states there is a countdown timer.

I should have proof read my post because what I was thinking, but then forgot to say was...

1.) "Under normal circumstances when"...

..."you're approaching a intersection where the light is green.. at some time in the future (of which you're unable to determine at that precise moment), the light will turn to yellow."

Then I should have continued with...

2.) "On the other hand if lights had countdown timers..."

..."you can look over to the right at the pedestrian walk/don't walk signal and see a countdown timer which is showing a number."

I guess that's what happens when my mind works faster than my fingers.

Nuvi1300WTGPS

--
I'm not really lost.... just temporarily misplaced!

@Nuvi1300WTGPS

It happens to all of us.

The primary issue with increasing the duration of the yellow to beyond the values found in the standard formula is the reaction from drivers. The problem is we adapt, the mechanical devices don't. If the lights are short cycling, then they should be adjusted, but extending the yellow just changes the "delimna zone" where the driver has to make a decision as to stop or continue through the intersection. That's not to say that increasing the length of the yellow isn't a solution, it's just one of many factors.

Studies show about 14 drivers out of a 1000 will "run" the light. Now, "running" means entering the intersection after the light goes to red. Putting in an all-red clearing time also helps reduce crashes. Most cities that have implemented a "clearing time" base it on the number of lanes. Remember it does take time to cross lanes and the time it takes depends on the average speed.

Why do people enter the intersection just after the light changes? There are many answers, but the most common one used by many opposing the cameras is that "yellow doesn't mean stop, red does." When I went through driver training and reinforced by many defensive driving courses is that the yellow light is a warning the light is changing and stop if it is safe to do so. The problem here with rear-end crashes goes back to "yellow doesn't mean stop."

As a generalization, drivers in North America have become much worse as skills have degraded. This is partially due to increased congestion because it causes drivers to become frustrated, but those bad habits shown when roads are congested carry over when the congestion isn't present. If you see what is happening around you as you drive, you'll find it's about the same number of drivers exhibiting "road rage" as those that run red lights.

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"In order to be old and wise, one first must have been young and stupid."

Additional Factor

I think an additional factor not mentioned by Box Car is that there are now so many more "distracted" drivers because of cell phones, tablets, etc. The "hoisting in" of the pending light change makes people more likely to try and beat the light (and a possible reason for that is that they have no idea how close the person behind them is to their vehicle).

If people are distracted, the countdown timers might not be noticed at all.

.

How about we just go extreme and use those bollards that shoot up from the roadway as soon as the light turns red? That'll be the end of red light runners AND we'll get them off the street when they total thier vehicles against it. Pretty soon, the streets would be safer for everyone.

Best Idea Ever.

Mpegger wrote:

How about we just go extreme and use those bollards that shoot up from the roadway as soon as the light turns red? That'll be the end of red light runners AND we'll get them off the street when they total thier vehicles against it. Pretty soon, the streets would be safer for everyone.

I've thought about this myself, I would support it 100%. Guaranteed to prevent repeat offenders grin

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Streetpilot C340 Nuvi 2595 LMT

Lights

Yeah, I suspect a decently long yellow paired with a 3 second red in all directions would be safest. Unfortunately in my city, Baltimore, they don't seem at all interested in adjusting the lights for safety and traffic flow, but instead invest tons of tax money in more and more red light cameras.

Lights

In my area, near Washington, DC the concept of yellow/red is unheard of. Yellow means speed up and red means only six more cars.

Love it!

Mpegger wrote:

How about we just go extreme and use those bollards that shoot up from the roadway as soon as the light turns red? That'll be the end of red light runners AND we'll get them off the street when they total thier vehicles against it. Pretty soon, the streets would be safer for everyone.

Unfortunately this might only work in non-snow belt areas. In winter water would freeze them up.

But I love the idea!

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Nuvi 350 long gone, Nuvi 855LMT, Nuvi 2797LMT, 3790LMT passed on to my daughter. Using Windows 10