Changing lanes is something most of us do every day, so it’s easy to get blasé about the dangers. We’ve done it so many times that we think nothing about moving from one lane to another.

factors that contribute to collisions, from defensive driving

#8 Changing Lanes
When Unsafe

But the dangers are very real and need to be taken seriously. If it weren’t dangerous, it wouldn’t be the 8th most common factor contributing to auto collisions, a factor involved in almost 23,000 car crashes in Texas in 2008.

Let’s look at the process from beginning to end and see how to make changing lanes safer.

This is a bigger deal than you might realize. When behind the wheel of a car, you shouldn’t do anything without a good reason, and that includes moving from one lane of traffic to another.

So why do you want to change lanes?

If you need to get over to exit, make sure that you decide well ahead of time so that can change lanes safely. If you know your exit is coming but you don’t know exactly when, stay in or next to the exit lane so you won’t have to make a mad dash at the last second.

And don’t let yourself get surprised at the last second. Pay attention to where you are and what exits are coming up. If that means putting down the cell phone or asking your passengers to hold the conversation for a bit, do it: no conversation is worth your safety, and your passengers should understand. After all they’re only as safe as your driving.

If you’re changing lanes to pass someone, why do you want to do that? Are they really going that much slower than everyone else, or are you just being impatient?

One of the most dangerous aspects of changing lanes is when you move into a lane where traffic is going the opposite direction, such as passing someone on a two-lane road. This is where many of these lane-change collisions take place. You really need to know the road ahead is clear for a safe enough distance. If there’s even a small chance that you don’t have enough clear space, don’t try it.

When it comes to passing, remember what Comedy Guys teaches in our defensive driving classes: you should only try to pass someone if it is safe, legal, and necessary. Don’t take foolish risks; don’t break the law, and don’t do it unless the car you’re passing is going at least 10mph under the limit. Any less than that, and you won’t be able to pass them without breaking the speed limit yourself.

You need to know your vehicle, too. How fast can it accelerate? Can it get around that other car in plenty of time? Is it running smoothly? When you in the other lane with a truck headed toward you is definitely not the time for your engine to stall.

This isn’t just for politeness, though that is important. It’s for safety. We’re safest when we know what the other drivers around us are going to do, and until we get vehicular telepathy worked out, turn signals are the best things we’ve got to work with.

And – as if we needed it – here’s another reason to not drive with a cell phone pressed to your head: with one hand on the wheel, you’ll need the other hand to work the turn signal. How many times have you been surprised by another driver who couldn’t signal because they were yacking away on their cell phone? Well, don’t be that person to someone else.

Put the signal on at least 100 feet before you change lanes. If you’re on a highway, just count the number of painted stripes on the road: four stripes and the spaces between them is safely more than 100 feet.

Here in Dallas (and probably in other big cities, too), there are many drivers who treat driving like a competitive sport. As soon as they know someone is trying to pull in front of them, their petty little egos get offended and they’re determined to shut that car out. To drivers like these, a turn signal is just an invitation to be a jerk.

But you can’t stop other drivers from being jerks, so don’t even bother. Signal your intentions anyway because it is safest for you and courteous to others. If one driver sees it and speeds up, you’re probably better off not driving in front of someone like that anyway. And for every ego-case who deliberately cuts you off, there’s another generous driver who’ll let you in.

(By the way, this is a good time to remind you to be one of the generous drivers. When you see someone signaling a lane change, give them some room and let them in. It’ll cost you maybe a second or two on your drive time and may prevent a lot of trouble for them and you if you contribute to a crash.)


  • Look forward, backward, and all around.
  • Check your car’s blind spots. Don’t just glance in your side mirrors: physically turn your head for a split second.
  • Check out other drivers. Are they maybe planning to pull into the same opening you want? Is anyone signaling? Does anyone look like they’re about to move without signaling?
  • Check your car’s blind spots again. Seriously. They’re called “blind spots” because the danger is hard to see. It’s worth looking again.

And if you have passengers, ask them to help you look. People in the back seat can see spots you can’t and they have more freedom to take their eyes off of the road ahead than you do.

sure that changing lanes is necessary and safe, and having signaled clearly to the other cars, and having checked and re-checked that the way is clear, change lanes.

And make sure to turn your signal off, ’cause that’s just annoying.