Can a traffic signal's YELLOW interval be less than 3 seconds?

Like, how long does it take to stop from 55 and remain under control ?

In a 25 zone? That’s part of the problem.

Agree I cant even get the truck stopped sometimes before red and I usally dont run as fast as the speed limit,you can see all kinds of black marks from dual wheels in the City I frequent a lot.But strangely enough most lights do seem to be 3 seconds as far as I can tell,but at 45 in a loaded truck its hard to get stopped,what really seems to help is the warning signals that tell you( at the posted speed limit,I assume) that the light will red when you get there.I used to love the old sychronized timed lights(hit a green and run the speed limit and it was smooth sailing)-Kevin

I’ve noticed those flashing yellow warning lights on Rte 1 in VA, @kmccune‌ . They are a big help, especially when the speed limit is 55 until you get near the light and it drops to 45.

I can’t see a consistent time working well. Some intersections are incredibly wide with multiple streets coming together. Try entering one of those from a low speed cross street and see how far three seconds get you.

We had a very dangerous intersection near us. A major street crested a hill just before crossing a major boulevard on the diagonal and another street for fun. Because it was a long signal drivers would fly over that hill and pay no attention to yellow lights. Lengthening the yellow would do nothing. What finally helped was putting a noticeable delay between the first street turning red and the other going green. Even with that we had a fool.on a bicycle plow through a crowded crosswalk and kill a man of close to eighty. Witnesses said he had been blowing through red lights for blocks. He was trying to set a new best time for one of the bike routes in the city.

There are web sites where you can post your times and even attach video and GPS printouts proving it. This idiot, the next day, created a record with his time and a GPS record of speeds. It showed that he hadn’t slowed at all until the last second. I don’t remember what his sentence was, but it wasn’t too trivial.

Before the signal timing was improved I’d see cars rushing at pedestrians, drivers leaning on brakes. Ugly driving, but now much less common.

There is no nation wide standard. Yes most states follow a certain standard like Just having Red-Yellow-Green…But not all. I’ve seen only Red and Green lights. The Red and Green on together will be the equivalent to Yellow.

Also the Red is on top…and Green is on the bottom…EXCEPT for one traffic light I know about in Syracuse NY…where the Green is on top. It’s in the old Irish section of Syracuse. Too bad if you’re color blind and go through the red light - thinking it’s green.

Leave it to the Irish. It must be some compensation for drinking and driving. Am sure that light was near a pub. But in the Irish section, you can ask, what isn’t near a pub ? Being Irish, it all seems “logical”.

There is one very important factor left out of the equation for calculating the yellow time, visual reaction time. Traffic safety experts claim that it takes the average person 1.5 seconds just to register a change in their environment. This factor is commonly used when determining safe speed limits. All this is according to the various “traffic safety schools” that I have attended at the request of a judge.

In addition to taking 1.5 seconds just for the brain to realize that the light has changed, it takes another .75 to 1.5 seconds (mostly age dependent) for people to react to that change, that is to apply the brakes. So even at 25 mph, three seconds is too fast.

And, it isn’t just reaction and braking time. Theoretically everyone gives plenty of stopping distance in crowded cities. Sure, but allowance has to be made to stop sanely instead of slamming on the brakes and screeching to a halt. It’s natural for most of us to check the rear view mirror before you enter an intersection, just to make sure you can stop quickly. More then once I have just cruised through a yellow to red because I was been tailgated.

@keith, the equation given in the link I posted earlier (and below) does include a variable for combined perception/reaction time.

It’s somewhat subjective, but they recommend using a perception/reaction time of 1 second.

I like in northern MN, yellow lights maybe 200 yards start flashing if you are not going to make it through the light. Also where I live the don’t walk signal flashes 11 times before the light turns yellow, I count the flashes to know if I am going to make the light or not.

It makes sense that something of that nature could be used to let the driver where in “count” the yellow light is. Another key in real accident avoidance would seem to me, the time between the red appears and the green goes on in the other direction or for left turn lanes.

@dagosa another variable, how soon the light turns green sure could be a factor.

Leave it to the Irish. It must be some compensation for drinking and driving. Am sure that light was near a pub. But in the Irish section, you can ask, what isn't near a pub ? Being Irish, it all seems "logical".

It is right near a pub. But it’s been that way for 80+ years. The reason is the Irish flag always flies with the Green on top. Back when they started to standardize the lights…the put a new light with the Red on top…The locals kept knocking it down. So they put back the Green on top…and kept it that way.

And there’s usually a cop hanging out near there to get you when you go through the red light.

Our pedestrian signals were replaced with LED signals (as were the traffic signalss, as in most places.) The new pedestrian signals have a countdown timer to when the signal turns red. Drivers also use them some as the numbers are fairly large and easy to read from a ways before the intersection… I’ve spoken with cabbies who find them indispensable. As a pedestrian I love them. They make it much easier to know if there is enough time to make it across.

To save gas, pollution and brake wear, I have use the count-down pedestrian signals since I first saw them. (And thanked the street departments for them.)

In my wife’s hometown in China, some intersections have large count-down traffic signals.
GREEN numbers in seconds appear: 40, 39, 38…3, 2, 1,
Then RED: 30, 29, 28…3, 2, 1,

Given what I’ve seen on TV of Chinese drivers, I’m surprised they bother. Those are scary drivers they have there.

Driving in China is a blast! An impromptu free-for-all.
They are the most skilled drivers in the world to do so well at avoiding collisions with everyone heading in every direction.
When your traffic signal displays a green <- ^ -> , the opposing traffic’signal displays the same!
Most signaled intersections have a permanently lit ->. You continue your right turn and traffic from your left helps you merge right in!

But at many in-town intersections, drivers often create a gridlock with eveyone getting in everyonelse’s way.
As a former (AAA) driver instructor, I have videoed their driving.

I’ve seen videos, and they were scary. Lanes? Never seen them. The striping seemed to go all over the place, so of course they’re ignored. Signals are just pretty colored lights. Given how willing the Chinese are to take on big projects I’m surprised they haven’t cracked down on unsafe driving. Maybe the number of new cars and drivers has overwhelmed them. Local government there seems weak and often corrupt, so maybe there is no one able to police driving honestly. Or they are using it as population control with survival of the fittest as the goal. Or at least those with the quickest reflexes.

I have seen a few videos depicting the most significant hazard on Chinese expressways, namely drivers who stop their cars in traffic lanes in order to run over to the side of the road to buy food or other items from vendors stationed there. Only in a country where people have little understanding of both the laws of physics and basic concepts of safe driving would you have a phenomenon of people simply “parking” their cars in traffic lanes of high-speed expressways.