Use of hazard lights


On freeways or interstates - as soon as I notice traffic ahead slowing down suddenly, I put my hazard lights on to grab the attention of people behind me.

I also use hazards for parallel parking as I stop to back up; and also as I back out of spaces in parking lots. [I figure it’s a visual signal of a reverse maneuver - like those beeping noises trucks make].

A friend told me that these lights should only be used when at a standstill.

I figure it’s not hurting anything, and could actually prevent a problem; but am I using my hazard lights excessively or illegally?


I know of no state law regarding the use of hazard lights. There is only the federal law requiring they be presnt on all new cars. After that everyone is on his own. State inspections don’t even check. (Someone can correct me on this.)

So you are not illegal. Excessive? Certainly not. I see them used all the time on slow-moving vehicles. A conscientious driver is giving everyone a sensible warning. Keep on doing what you are doing. Ignore your friend. He knoweth not.


Excessively. Your turn signal and reverse lights should be enough when parallel parking. And for sudden slow-downs, it may be OK, but turn them off once the car behind you has also slowed. Leaving them on is a nuisance, and besides, it already did the job you wanted, so please, turn them off. I believe brake lights with the third brake light should be enough. But I drive an SUV. I only use hazard lights when I’m stopped on the side of a busy road, or limping my car home much slower than surrounding traffic. If I’m going near legal speed, even if driving carefully, I leave them off.

My pet peeve is people that will turn them on, and continue to drive at legal speed or better. If your driving that fast, what is the damn hazard? It grates my nerves, and I find it very distracting and annoying. Also, the people that will turn them on when it is raining hard, slow down, but do not move the the right lanes. Just stay in the left like they are scared to move. Then it just becomes dangerous.


I also use my hazard lights if it is necessary to come to a sudden stop on a highway or even to slow down a lot, as it gives any inattentive drivers behind you an extra warning that you have slowed or stopped. After all, with so many self-absorbed people yakking endlessly on cell phones, it has become important to give as much warning as you possibly can. But, as was said, once it is clear that traffic behind you has slowed down sufficiently, it is a good idea to turn the hazard lights off.

I think that double-parking is also a good time to use these lights, as is parking on the shoulder of a road, but apparently most people do not agree with you and me. Every day, I observe cars parked on interstate highway shoulders (extremely close to the travel lane) with either no lights illuminated or only a directional signal illuminated. But, since so many of them can’t figure out that it is not a great idea to park 2 inches away from vehicles traveling at 70 mph, I don’t think that you should use these people as role models.

My advice? Continue to use the hazards as you are and you are likely to avoid some accidents that might occur without the use of them. While I never thought to use them when backing out of a parking space in a mall parking lot, given the number of collisions that I have observed in parking lots, this might be a good idea. Perhaps a bit excessive, but if you avoid an accident in this manner, then your instincts were correct.


Your friend is nuts. It is sometimes required (or maybe it is just urged?) to use hazards below certain speeds on, e.g. interstates.

I always think that the use of hazards as an attention grabber for unusual things (like sudden slowdowns or excessively slow speed) is a really wise thing to do. Though as BustedKnuckles says - turn them off once the situation is settled down.

I personally don’t use them for parallel parking or backing out of a parking spaces because to me those don’t count as “unusual” situations - they are perfectly routine.

I will mention one potential problem w/ regards to parallel parking - your intention in parallel parking is to stop next to a line of parked cars and then back up into a space. The best way to signal that is with your turn signal. Your reverse lights then come on, and that is how people know what you are trying to do. If I see a car ahead of me pull over to do this, the correct thing to do is stop and yield the right of way for the driver to park.

 BUT, if I see a car pull over next to a line of parked cars and turn on their hazards I am going to assume that they are going to temporarily double-park.  So now, instead of yielding the right of way, I will go around them.  I would say NOT to use the hazards for parallel parking.


Agreed on all points!

To expand on the interstate thing, I believe NY has a law that if you’re going more than 20 mph below the posted speed limit, you must use your flashers. On the other hand, I believe that in certain states, like Florida, it may be illegal to use your flashers while moving.

I would stop by your local police department or check your DMV’s website and figure out what the law is in your state.


As truck drivers we are trained to use our hazard lights whenever traffic slows below 45 MPH on a highway and whenever we are pulled over on the side of the road. I have recently read that if you pull over in the fog that you should not use your hazard lights because someone might see them and assume your vehicle is moving. If you pull over in the fog, I guess the best thing to do is get as far off the road as possible, possibly getting behind a sign or the side of an overpass for protection, and turning off all lights so that other cars won’t be attracted to follow your path.


I agree with you Jeremy. Can you explain to me why so many people seem to think that it is a good idea to park on the shoulder literally right on the line between the shoulder and the right lane?

Because they are so close to the right lane, I have seen people actually squatting in the right lane in order to change a tire. And, this is despite the existence of at least 3 or 4 feet of shoulder to the right of where the car was stopped.

If I have to pull off of the road, I actually will pull at least partially onto the grass, so that I am as far off of the road as possible. If I need to jack the car up, I have a small piece of 3/4 inch plywood to put underneath the jack, so that it doesn’t sink into the soft ground.


Do what you are doing.


I am in Mexico, and spend a lot of time here. The driving culture is sort of insane. But, one thing I do like is the heavy use of hazard lights. They tend to use it like the truck driver said, any time they are driving below the flow of traffic. Backing up; in some cases turning left across oncoming traffic. A major bus line uses hazard blinkers every time they slow down for the ubiquitous speed bumps. Once one gets used to their use, it really does help a lot.

When you see blinkers, you know you need to look out for something. Not just slowing down. I take blinkers as a sign also of “I am going to do something really stupid.” :slight_smile:

A few years ago, having learned this, I was going east through Des Moines on the Interstate. It was somewhat icy. Cars ahead had their brake lights on, but it was not easy to tell in the gloom just how slow they were going, so in the end, I had to use some fast maneuvers to avoid a close call.

Looking in my rear mirror, there was a large group of cars coming up fast. I popped the hazard lights, and almost instantly they were slowing down as fast as they could. They thus had a lot of time to get down to our speed with no close call.

This is one thing we could learn from Mexico.

The stupidest thing I see in Mexico is using the left turn signal to let someone behind you know it may be safe to pass – or not, good luck.

Note that this makes it dangerous to use your left turn signal to turn left on the highway. Sigh. So, when you plan on turning left you have to do something like wave an arm out the window. when I am turning left when that left turn signal could mean pass me buddy, I put on the hazard blinkers, and if traffic is going fast, also wave the arm out the window.


I also do this. You’re using them to warn others of a hazard, and that’s the best and most appropriate use of them. Preventing accidents is the most important part of safe driving, and warning others of a hazard is preventing accidents.