Chet Skwarcan is an award-winning engineer, writer, and industry innovator in the field of traffic engineering. He is known for leveraging his creativity, logic, and technology to solve today’s engineering challenges.

Traffic Falsehoods

Some of the Things We Believe about Traffic are Counterfactual

Here are a few beliefs we have about traffic that are not true…

Cars coming toward me at a traffic signal are still moving but the light is red so they are running a red light. More likely they have a green light. “Smart” traffic signals are programmed to adjust directional green times based on the physical presence of vehicles and historical traffic volumes for each direction by time of day, day of the week, and color of your car (I recommend black and white).

When turning left at a traffic signal, wait in the intersection until a gap appears in traffic (or until the light changes).Unless you are very familiar with the intersection, this could be a bad idea. In some cases, your light can turn yellow and then red without a gap appearing in oncoming traffic (see above). This might be a good time to mention the “yellow trap” (see below).

I just heard about something called the “yellow trap.” What is it? Glad you asked. As recently discussed, it’s possible while waiting to turn left, the light turns yellow and then red but oncoming traffic continues. Next thing you know, sidestreet traffic starts to move. You’re trapped. To reduce the instances of this happening, many DOT’s are installing flashing yellow arrows to extend the time allowed for turning left (but remember, you must continue to yield to oncoming traffic).

We have a speeding problem in our neighborhood so we need more stop signs. Installing stop signs to control speed is a bad idea. Studies have shown drivers speed up between “unwarranted” stop signs to make up for the lost time. Of course, if stop signs are actually warranted, they should certainly be installed. But if they are not warranted there are ways to reduce speeding.

Bicycles are like pedestrians. Not true — bicycles are considered vehicles and subject to Indiana traffic laws. The only time a bicycle is considered a pedestrian is if the rider dismounts and walks the bike (like in a pedestrian crosswalk).

Traffic signals prevent accidents. Traffic signals can only reduce accidents (I’m assuming we are talking about traffic signals that are actually warranted). Signals reduce accidents but may increase certain types of accidents such as yellow-trap and rear-end.

In summary, traffic is complicated. And although you just became a little bit smarter, keep in mind not everyone reads about traffic (go figure). And because not everybody reads about traffic, please drive defensively. Someday, when you least expect it, that car waiting to turn will pull out in front of you. But you’ll be ready.

Chet Skwarcan (traffic engineer, author, unique insights) with over 25 years of traffic engineering experience — online ideas available at