What is a Blind Spot?

Jeremy Laukkonen

In the automotive sense of the term, a blind spot is the area outside the normal field of vision that can't be seen without turning around or turning the head. Blind spots generally occur due to the inability of side and rear view mirrors to show everything to the sides and behind a vehicle. Larger vehicles, such as semi-trucks and motor homes, typically have larger blind spots, but even cars, trucks, SUVs and boats usually have a blind spot or two.

Teenage drivers should be particularly aware of blind spots before driving a vehicle.
Teenage drivers should be particularly aware of blind spots before driving a vehicle.

To be as safe as possible out on the road, it's important to determine where the blind spots are in any particular vehicle before driving it. The easiest way to do this is to sit in the driver's seat, look in the mirrors, and then turn around and compare the two views. Anything that's visible by turning around but doesn't appear in the mirrors is considered to be in a blind spot.

It's important to find the blind spot of a vehicle before driving it.
It's important to find the blind spot of a vehicle before driving it.

The blind spot can become especially dangerous when doing things such as changing lanes or parallel parking. If there is a blind spot on either side of a vehicle, it becomes possible to accidentally merge into a space already occupied by another vehicle, with costly and sometimes dangerous consequences. If the blind spot is known, a quick look over the shoulder can alleviate all possible chance of an accident. Similarly, blind spots can make it difficult or impossible to parallel park without hitting the other vehicles. Turning around to assess the situation can fill in the missing information from the blind spots, allowing for a safe parking job.

It is also important to consider the blind spots of other drivers when out on the road. Many people don't think to look over their shoulders when turning or changing lanes, so when driving in another driver's blind spot, it is always safest to assume they don't know anyone is there. This is especially important when considering larger vehicles, as their blind spots might cause an entire vehicle to virtually disappear while alongside it. It is generally safe to assume that if the mirrors on a large vehicle can't be seen, that driver doesn't know another vehicle is present. If their mirrors are adjusted incorrectly, however, they might not be able to see even if their mirrors are visible to another driver.

Driving large vehicles also presents several unique problems. With semi-trucks and some larger motor homes, it's simply impossible to see everything in a blind spot by a simple turn of the head. Large mirrors can sometimes minimize blind spots, and rear and side view cameras can allow drivers of very long vehicles to see into their blind spots. Measures such as these can make the roads much safer for everyone by virtually eliminating blind spots altogether.

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Discussion Comments


My new car has some driving aids that are supposed to help eliminate blind spots while on the road. I think it uses laser light or something to detect objects I can's see in my mirrors. I was glad I had it when I tried to change lanes in traffic and I didn't see a car coming up fast on my left. He was in my blind spot, but the driving aid system still "saw" the car before I did.

I've heard there are conventional car mirrors available that are better about blind spots. They can be angled to provide a better blind spot visual field. I've never tried them, and I'm not even sure they exist, but if they do, I'd get my son and daughter a set for their cars tomorrow.


There's also the blind spot in a person's eyes that will make things disappear for a second or two. I remember looking at two dots on a piece of paper and seeing one completely disappear when I closed an eye.


I remember my drivers' education instructor had a rule for us to remember while driving on major highways and Interstates. He said if you are behind a truck and you can't see the driver's face in his rearview mirror, you are in one of his blind spots.

Whenever I encounter a large truck on the highway now, I make a point of staying back a few car lengths in case he decides to change lanes and can't see me. If I really need to get past him, I will drive as fast as I can until I'm clearly in a position where he can see me again. I hate being caught right next to a truck like that in heavy traffic.

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