What to do when the light turns yellow?


yellow-light.jpeg The answer is simple: STOP. According to the law, every driver has to stop at a yellow light unless he or she is too close to the intersection to stop safely. So, how do you define “too close” to the intersection?

The point of no return

One rule of thumb is that if you are 100 feet or less from the intersection, you have passed the “point of no return” and cannot stop safely before the intersection. Therefore, it is best to continue at your current speed through the intersection, but be cautious as you pass through.

Another rule of thumb involves a little math as well as an understanding of braking. Let’s explore the following situation: You’re driving at 30mph and the traffic light turns yellow. You’re approximately 125 feet from the intersection. Have you reached the point of no return?

Here comes the math: It’s going to take you (a seasoned driver) approximately 1.5 seconds to recognize the need to brake and to begin applying the brake. Your car will travel 66 feet during those 1.5 seconds. Once the brake is applied, it will take your car another 43 feet to stop. Therefore, your total stopping distance is 109 feet. Therefore, you have not yet reached the point of no return and you should stop.

Obviously, you can’t perform that kind of math while driving. So, as you approach an intersection, you need to pick out a reference point along the side of the road that will represent the point of no return. So, if the traffic light turns yellow, you can instantly make the decision to continue or to stop.

Be aware of cars behind you

As a good driver, you should always know if you’re being tailgated. As you approach an intersection, use your brakes to get a tailgater to back off a little bit. You don’t want them to slam into you if you must stop quickly at a yellow light.

The higher the speed limit, the longer the yellow light

Based upon the math we were doing earlier, it would make sense for yellow lights to last longer if the posted speed limits are higher. A common rule of thumb is that for every 10 miles per hour of speed, the yellow light will last 1 second longer. However, don’t count on this. You should always err on the side of safety. If you run a red light, a police officer is not going to care that you crossed the point of no return. His response will be that you clearly need to work on determining its location.

Green = go. Red = stop. Yellow does not equal “gun it”!

Many drivers see a yellow light and start driving like they stole something. Don’t do that. Remember, if you’re crossing into an intersection and the light becomes red, you’re breaking the law. You’re also creating a dangerous situation for cross traffic.

When teaching your teenager how to safely negotiate an intersection controlled by a traffic signal, consider the speed at which you are traveling as well as the distance between your car and the intersection. If you’re following other cars, it’s a good idea to use cover braking in case the traffic light turns yellow and you need to stop.

Running a red light is incredibly dangerous

Although the purpose of this article is how to determine the point of no return, it’s worthwhile to mention (again) how you should always err on the side of safety. Think about it: If your light is red, that means someone else’s light is green. You’re basically playing chicken (or, more accurately, Frogger) with a 3,000 lb missile. What I’m saying is simple: If you’re within the vicinity of your point of no return, stop.

Okay, you’re invincible. But, is it worth the ticket?

Many new drivers, due to their age, are invincible. As we all know, teenagers are immortal. They’re also the smartest of all humans. Therefore, my arguments regarding danger are, admittedly, irrelevant.

However, teenagers are not independently wealthy. Nor are they immune to tickets and jail. So, is running the red light worth getting the ticket? As you are well aware, many municipalities across the United States have started to install red light cameras. These cameras take pictures when the signal switches from yellow to red in order to catch red light runners. Shortly thereafter, the red light runner receives a ticket in the mail.

I hope that the next time you see a yellow traffic light, you don’t think about this article. Rather, I hope you simply stop and enjoy the rest of your drive.


3 Responses to “What to do when the light turns yellow?”

  1. bevoost on May 1st, 2009 3:27 am

    How many times has a traffic light turned yellow as you approach an intersection, and you are uncertain if you can make the light or not? For me this is a daily occurrence. My typical route to/from work is along a highly-trafficked boulevard traversing through northeast Philadelphia. Traffic lights break up the long stretch of boulevard every quarter mile or so. One day during my commute home, I discovered a systematic way to determine if I can go through or should slow down for the yellow traffic light.

    First let’s go over the basic layout of an intersection. At the point of intersection, a traffic light facing drivers approaching the intersection is suspended above the road. A solid white lane line (SWLL) extends out from the intersection and eventually turns into a broken white lane line (BWLL). So, as drivers approach an intersection, the lane line changes from broken to solid and then ends at the traffic light.

    The length of the SWLL extending out from the intersection is curious, because there appears to be no standard length. Yet, it seems doubtful that the length is determined haphazardly by the steamroller operator. (I can just imagine him thinking to himself, “Let’s extend the solid white lane line to right about….here. Yeah, this looks good.”) My left brain mind presses me to believe that the length of the SWLL is not arbitrary and must be calculated.

    I vaguely recollect when studying for the written part of the driver’s examination (which, by the way, I failed…twice) that switching lanes is prohibited in the SWLL area, and is allowed only in the BWLL area. But could the SWLL also serve the purpose of indicating to the driver if it is safe to proceed through a yellow light or not? Thus arose the “Roosevelt Boulevard Experiment”, a two-week test of man against traffic light.

    The “Roosevelt Boulevard Experiment” had three basic rules. Rule #1 was to to drive as close as possible to the speed limit. Doing so allowed me to rule out the possibilities that driving too slowly was the reason for not making the light, and driving too fast was the reason for making the light. Rule #2 was to always wear a seatbelt. Afterall, the SWLL might have nothing at all to do with the traffic light. Rule #3 was to tell noone about the experiment. This would prevent other lunatics from trying this experiment too.

    The results were very surprising! About 95% of the time my hypothesis held true, i.e. if the light turned yellow when I was in the BWLL area, I would not make the light, AND if the light turned yellow when I was in the SWLL area, I would make the light. The remaining 5% resulted in some near-death expieriences I’d rather not elaborate upon.

    There are several factors at work here – Speed (i.e. speed limit), Time (i.e. yellow light’s duration), and Distance (i.e. SWLL’s length). Let’s see what happens when each of these factors is made a constant. Scenario 1: If the yellow light’s duration is constant, then the faster/slower the speed limit, the longer/shorter the SWLL’s length. I have not yet experienced two yellow lights that share the same duration. Scenario 2: If the SWLL’s length is constant, then the faster/slower the speed limit, the shorter/longer the yellow light’s duration. It is also my experience that no two SWLLs share the same length. This scenario is the most dangerous, especially as speed increases or the yellow light’s duration decreases. Scenario 3: If speed limit is constant, then the longer/shorter the SWLL’s length, the longer/shorter the yellow light’s duration. This scenario appears to be most reasonable, as both the yellow light’s duration and the SWLL’s length are both variable, and to represent reality most closely.

    Therefore, if we assign Speed and Time, we can solve for Distance using the following simple algebraic equation: Distance = Speed * Time, or SWLL’s Length (ft) = Speed Limit (ft/second) * Yellow Light’s Duration (seconds). For example, in a 30mph zone, and a 3-second yellow light, the SWLL would be 132 feet.

    In the end, my “Roosevelt Boulevard Experiment” yielded little more than empirical evidence and a few induced out-of-body experiences. My hypothesis remains unproven. This is really a shame, because I am certain my hypothesis, if proven, could be of interest to thousands of personal injury lawyers out there handling cases involving intersection-related accidents. And, more importantly, the anxiety a yellow light traffic incites in each of us each day might finally disappear…

  2. Earl on May 27th, 2009 8:14 pm

    Re: stopping on yellow. In which states is that the law ? At least in Calif the yellow is considered an extension of the green. It is legal to enter on yellow. Getting stuck in the intersection & blocking traffic is not legal.

  3. admin on August 17th, 2009 4:10 pm

    @ Earl – I’m not aware of any states in which stopping on a yellow is required. Stopping on red, obviously, is always required. Also, you do not want to be in the middle of the intersection when it turns red. Not only could this result in a ticket, but it can be extremely dangerous for cross-traffic that is entering the intersection.

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