wwcd101

Needless to say, I ran a red light this morning.

I was wondering if there was a standardized length of time in the u.s. that a yellow light is supposed to stay on for before switching to red?

Thanks for listening.

Bill O'Rights

Nope. The Yellow light is intended merely as a warning that the light is about to turn red. If you are already in the intersection...then, by all means, proceed. If, however, you are not in the intersection, when the light changes to yellow...then stop.
My guess is that you were playing a game of "Beat The Light"...and lost? Perhaps to the tune of a traffic citation? I could be reading way more into this than what there really is, but the length of time the lighted stayed yellow will not be a valid defense in a courtroom.

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Jinn

There's definitely no standard. I've seen some that are 1-2 s, and I've seen some that are 5s. I think its entirely determined by the city and the intersection..

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splck

It would depend on the size of the intersection. A one lane VS a four lane intersection would be different so cars could clear the intersection.

My car was totaled by an idiot running a light a number of years ago, and watching them do it pisses me off to this day. Pay attention to "stagnant green lights" because you know they are going to change to yellow at any time.

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BonesCPA

There is no standard. The yellow light and the delay between a direction turning red and another turning are all used to control traffic flow. The yellow does take into consideration speed limits and braking time.

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wwcd101

Once again, this is such a great group. I very much appreciate the feedback.

Here's the story. Really, several things combined to sink my fate here. I was on my regular morning commute, definitely daydreaming, heading down a fairly steep hill in our super light and nimble Chevy Suburban. Speed was probably a little high due to the hill, call it 40 in a 35.

The light went to yellow. My first thought was to brake and I touched them, slowing slightly. My next thought was that i was going too fast to stop gracefully, momentum is a powerful force, I hit the gas and the light turned red as i arrived at the intersection. By the time I got the whole boat through, 3 seconds may have passed.

Well that's what the motorcycle cop who was sitting right there said.

Upon reflection, it seemed like a short yellow. But then it occured to me that I didn't know what a normal yellow was. Now I know that there is no such thing.

Thanks all.

Thanks for listening.

Redlemon

Just FYI, they call that "driving too fast for conditions". I'm not judging you, however.

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Rodney

Never a good idea to shoot the yellow unless you're within two or three carlengths (or one second of driving distance at whatever speed you're at) of the intersection.

First, you might meet someone jumping the gun in the other direction. Second, the lights might be mistimed so that the yellow is still shining in your direction while the lights switch to green for the intersecting street. This happend to my wife; she crossed on a yellow and a car t-boned her from the crossstreet. She knew she was on yellow, the other guy swore his light was green. The insurance company divvied up the blame more or less equally. Later, she went back to the intersection to check things and, sure enough, the yellow and green lights for the intersecting streets overlapped by one second.

She never did go back and sue the city, but she should have.

kutulu

That's messed up the driver with the green should have been assigned more (if not all of the) blame. The driver at a dead stop should be responsible enough to look before he goes.

goddfather40

At least in California, I am almost positive that there is a standard on the minimum duration of yellow lights. It is based on the speed limit of the road in question. It may only be a standard for signals with red light cameras, I'm not sure. I recall a news article about an intersection with a red light camera up in the Bay Area, Union City to be exact. Apparently, someone got a ticket from the camera and fought it successfully by sitting at the intersection and measuring the yellow light duration. The duration was below the minimum duration based on the speed limit of the road and he got his ticket rescinded. Not only that, but everyone else who got a ticket at the intersection from the camera had there tickets rescinded as well. The city of Union City lost a ton of revenue.

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Lebell

Actually, I believe there are standard recommendations, but what they are specifically, I don't know.

If I were serious about finding out, I would check the DOT website and some industy organizations, since they are the ones that tend to come up with such standards.

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Xazy

I know of a traffic light that can turn from green to red to green again in 4 seconds. And it was a busy traffic signal that would change based on weight sensors. This was the most freaked up light, causing a number of accidents. It was only until this past summer when a child was killed because of it, that they changed the light (about 14 years since the first complaint to the town).

shakran

And if you think lack of standards is bad, get this. Some towns have been caught monkeying with the yellow light timing to increase ticket revenue. They'll have it on for, say, 5 seconds for a month to get people used to it, then they'll drop it to 2 seconds and catch the people who think they have time to make it through.

If your town is doing this and you could prove that, you'd have a case.

Otherwise. . .don't run reds

sblime42

Actually, I believe California law requires yellow lights to be at least 4 seconds long. I'll see if I can dig up a citation for you.

*edit* this is what I've found so far:

http://www.dmv.ca.gov/pubs/vctop/d11/vc21455_7.htm

Seems it may just apply for lights that have cameras. I'll keep looking.

Ok this is what I've found:

Table 4D-102 Minimum Yellow Light Change Interval



Posted Speed or Prima Facie Speed Minimum Yellow Interval
MPH / SECONDS
25 or less / 3.0
30 / 3.2
35 / 3.6
40 / 3.9
45 / 4.3
50 / 4.7
55 / 5.0
60 / 5.4
65 / 5.8

Seems they are related to how fast the posted speed is. Again, these supposedly only apply to lights with cameras on them. I do not believe this law applies to regular lights.

God of Thunder

Traffic light timings are based on several things:

1. Width of the road
2. Speed limit
3. Average traffic count

Michigan's standards are similar to what is posted above. The new standards also include what is called and "all red" for safety. Currently most lights are set up so that one side goes to red and the other side goes to green at the same time. This contributes to accidents when the person trying to beat the light may still be in the intersection when the other direction turns green. Now they want to have both directions at red for at least two seconds to give the intersection time to clear.

As to the original post, however, you said the light was yellow for about 3 seconds. You also indicated it was 35MPH zone. I'm afraid my research shows that to be pretty normal, at least for Michigan. I would guess that most states are pretty similar.

My information come directly from the traffic engineer for the City of Flint (I had to fix his PC this morning). The city sets all of it's lights to MDOT standards.

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thingstodo

I think it also depends on the police officer watching.

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BigBen

Holy shit...

I consider myself a seasoned driver, and have only been in 2 accidents in my life. Both non-preventable, both not my fault. I have been involved in driver training and examinations.

I have taken defensive driver, winter driving and safe backing courses.

I perform a daily inspection of my vehicle (one of my obsessive compulsive disorders) to ensure that I will have a safe trip.
I stow all articles in the passenger compartment to prevent shifting during vehicle manouvres.
I ensure that all of my passengers are wearing seatbelts properly and at all times.
I do not drive after consuming alcohol or medications that may affect my abilities.
The only thing I am guilty of is that I do not always ensure that I am properly rested.

I have never heard of lights where the "All Red" was not in place. Every intersection I have ever crossed has had a safety interval in place. To think that this is not a universal driving rule scares me. I will be more attentive if I ever drive in Michigan.

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sblime42

Most of the lights in San Francisco lack the "all red" safeguard. This is understandable as SF has quite a bit of traffic going through its streets and such a system would slow things down even more.

MSD

If I had to guess why those times were picked, I would put a few bucks on my theory that it's the amount of time it took a test vehicle to come to a full stop from the posted speed limit when the law was written, plus ten or twenty percent for a margin of safety.

I've started to pay attention to the solid white lines that lead up to a multi-lane intersection from the dotted line, and the line is about 1.25 times the distance it takes me to comfortable come to a stop from the posted speed limit. I have yet to cross the white line as a light turns yellow, but I suspect that braking time from the end of the white line corresponds to the yellow light duration.

kutulu

Lights in downtown Phoenix don't have that either. The ironic thing is that these are some of the highest traffic areas that could really benefit from them.