You are about to be rear-ended. Is it better to open the door?
May 18, 2013 5:17 AM   Subscribe

You are about to be rear-ended. Is it better to open the door?

I was once in a fairly significant accident where I was rear-ended.
What sticks in my mind is that I saw the guy coming from behind as I was stopped.

I keep wondering if it's better to open your door when you think you are about to be hit from behind or to keep it closed.
An open door can't be jammed shut and thus enables rescuers to get to you faster but does it weaken the structure of the car as well?
posted by krautland to Travel & Transportation (26 answers total) 2 users marked this as a favorite
 
I would think it would be better to take the impact square across your back, rather than potentially be caught sideways as I was messing around with the door, etc.

I think the best course of action would be to start hitting the horn as hard as possible.
posted by jenkinsEar at 5:30 AM on May 18, 2013 [1 favorite]


This happened to me a few years ago. I was stopped in traffic on the highway, and the guy behind me wasn't paying attention enough to realize that traffic was coming to a standstill. Whenever I come to a stop, my instinct is to look in the rear-view mirror, so I saw the guy coming. I remember thinking "oh, he's going to hit me" and deliberately decided to brace myself by putting my arms across my chest and ducking my head in them. Whether this was the right thing to do at the time, I have no idea - but I ended up with just a few minor bruises on my arms, after the momentum of the guy in back pushed me into the car in front of me.

Being wedged between the two cars crunched my car (obviously totaled), and I remember the door taking some shimmying between me and someone outside.

My guess is, when you're watching an accident about to happen, time slows down tremendously. The time between realizing an accident is about to happen and the moment of impact is not more than a second or two - but feels so much longer. If it was longer, I think a lot of people would have the foresight to drive out of the way or get out altogether. I think it's difficult to put together a plan of action in such a small amount of time, other than quick instinct (which could include opening the door depending on the person). But a lot of newer cars also have side airbags that could prove to be beneficial, even life-saving.

FWIW my airbags didn't open in my accident, and I've heard that airbags opening is not always a good thing. But despite the severity of the accident, I walked out completely fine (and bought the same car from the insurance payout).
posted by raztaj at 5:33 AM on May 18, 2013 [1 favorite]


No, you shouldn't open your door. Rescuers know how to get through doors pretty quick these days. By opening your door I suspect you would be increasing your risk of additional injury. Following a hard collision from behind, your car will be driven forward and potentially at an angle depending on the point of impact. I suspect that in the absence of other entities for your car to collide into, that much moment will slam the door open and then potentially back against the car. In the meantime, you will be slammed forward, and depending on your position (you have now leaned left assuming U.S.) how your seat belt and air bag react, there's a reasonable chance you, your head, or your flailing left arm will be slammed into either the door itself as it recoils, or out of the car before it recoils. That doesn't sound good to me. If the first collision leads to a secondary collision or further, having your door open only makes matters even worse.

In other words, if you like your left arm or your head, keep the door shut. No science though, just speculating.
posted by drpynchon at 5:34 AM on May 18, 2013 [2 favorites]


say you've pushed open the car door before being rear ended, what happens when you're hit? your car is shoved forward and the door slams back shut. so now there's a car door slamming shut next to you as you're being thrown around in the impact. depending whether you've managed to pull your arm back in after opening the door, you could be losing some fingers there.
posted by russm at 5:34 AM on May 18, 2013 [1 favorite]


The more collision energy is used to deform the door, the less collision energy gets imparted into you.

Modern safety engineering in cars is to let the (replaceable) car take the brunt of the impact and get destroyed, diverting energy away from the soft, squishy passengers inside. The door is part of the structure of the car that absorbs the energy.
posted by chengjih at 5:38 AM on May 18, 2013 [35 favorites]


Sure, if you can hop out and safely escape.
When I stop quickly and worry that folks behind may not follow suit, I often click on my hazard lights for a few seconds. When people in front of me do that it helps knock me out of my driving trance and alert me that something is up. Honking the horn isn't a bad idea, either. Don't open the door. The car is engineered to receive impacts and crumple in a way that won't squash you. Opening the door could negate that.
posted by bonheur at 5:40 AM on May 18, 2013 [1 favorite]


The doors and roof of your car are structural elements that contribute to the car's rigidity. Opening the door is reducing the strength of your car at the moment you need it most. Leave the door closed.
posted by workerant at 5:40 AM on May 18, 2013 [6 favorites]


Also, you could be thrown from the car (even if you're wearing a seatbelt) and get run over by another car or be slammed and trapped by wreckage...would be my guess.
posted by vitabellosi at 5:52 AM on May 18, 2013


Cars are designed to crash with the best outcome for the occupants when the doors are closed and they are in a normal seating position.
posted by BenPens at 6:15 AM on May 18, 2013


//I often click on my hazard lights for a few seconds.//

It seems like it would be relatively trivial to design the hazards to do this automatically when braking with more than normal force. It also seems like it might not be a bad idea as I can believe that would avoid a few rear end collisions.
posted by COD at 6:42 AM on May 18, 2013 [3 favorites]


Brace for impact. Sit yourself firmly back in the seat, and wait for it.

This happened to me years ago. I was sitting at a light and saw a truck coming up from behind quickly. I thought he was going to stop, but I didn't see any indication that he was slowing. It quickly became obvious that he was going to hit me, and I quickly braced myself back into my seat just before he hit.

Added excitement bonus: I had a backseat full of fireworks.
posted by Thorzdad at 7:14 AM on May 18, 2013 [12 favorites]


Don't open your door for the reasons laid out already: the door increase the structural stiffness of your car and a closed door keeps you in the car. Ideally a modern car is so stiff that the occupant area is unaffected and the door will operate easily. It is especially important to keep the door closed if you have door mounted seat belts.

raztaj: " I remember thinking "oh, he's going to hit me" and deliberately decided to brace myself by putting my arms across my chest and ducking my head in them. Whether this was the right thing to do at the time, I have no idea - but I ended up with just a few minor bruises on my arms, after the momentum of the guy in back pushed me into the car in front of me. "

Ideally one wants to be pressed firmly against the seat in a rear end collision to reduce the amount your head flails around; to allow seat belt tensioners to do their job and to keep your head away from a potentially activating airbag.
posted by Mitheral at 7:25 AM on May 18, 2013


Yes, you should keep the door closed. If you've ever looked inside the door of a modern car, you'd see why. There are relatively giant steel pipes in there that serve to absorb and deflect force around you.

And yes, your first reaction should be to place your head firmly against the headrest. The impact will want to propel your head backwards, and there will be less damage if your head doesn't crash into the headrest. I suppose crossing your arms is a good idea, but I'm not sure.
posted by gjc at 7:41 AM on May 18, 2013 [1 favorite]


COD, check out the Voevodsky Cyberlight.
posted by jet_silver at 7:45 AM on May 18, 2013 [1 favorite]


Impossible to rate it as a strategy without data.

What you can say is that the impact will move the car. The designers have spent a lot of time thinking about occupants and what happens and they have data on highly choreographed test collisions. In the unlikely event your exact scenario has been assessed, it wasn't assessed with an open door, which would constitute a random variable and a random configuration and yield test results of no use whatsoever.

If you have enough time to open the door, you have enough time to accelerate and reduce the relative speeds of collision. It's a good idea not to stop too close to people in front of you so you can have some escape route flexibility, but the thing about accidents is that they happen when you don't expect them. I had a friend rear ended at the end of an interstate exit ramp by a big car going 70. in the hospital for weeks. bad scenario and i think of it when i exit, often.
posted by FauxScot at 7:51 AM on May 18, 2013


We'd have to assume that all safety testing is done with several premises in mind, one of them being that the doors are shut, which means that the safety equipment was designed around that idea. Remove it and you might remove how well some of it works, whether it be crumple zones or side curtain airbags.
posted by Brian Puccio at 9:07 AM on May 18, 2013


I was just considering a cardboard box.

When I push against a wall of the box while it's sealed up, it stays a lot more rigid and carries more of the force evenly around the wall I'm pushing on. But if I open the box and push on that wall, then the box is a lot more flexible and actually deforms the most where it's open.

Not saying car designers don't take open doors into account, or that a cardboard box is an adequate model of a car, but the physics of a car crash are a lot more violent than most people imagine and I'd want the car to have as much structural integrity as possible.
posted by Mercaptan at 10:03 AM on May 18, 2013


If you have a spring-loaded centre punch at hand (whether a regular one for crafts/woodworking, or one intended for window-breaking such as ResQMe), you will be equipped to get out the door whether or not you are able to take any action in advance of the crash. And you will be equipped to help others do the same when you're not involved in the crash.

(I keep a ResQMe on my keyring -- I have no other connection to the brand)
posted by winston at 12:04 PM on May 18, 2013


A couple of folks have suggested honking the horn; this is a bad idea because you don't want your hands near the center of the wheel if the airbag goes off.
posted by Johnny Wallflower at 12:05 PM on May 18, 2013


If you watch this video of the Paramus extrication team in competition, you'll see they start working on the driver's side door at 4:08 and lift the door away at 5:18. So, even if there were no concerns about the strength of the car, this is unnecessary. Modern rescue teams are really good at opening cars.
posted by d. z. wang at 12:15 PM on May 18, 2013


If one of your limbs ends up outside of the door during the collision, that same limb might be outside when the door slams shut again.

I've treated this injury. It's ugly. Don't open your door.
posted by kamikazegopher at 5:34 PM on May 18, 2013 [2 favorites]


The Insurance Institute Highway for Safety has a diagram that explains the forces on your body in a rear collision. It is very important to have the head rest adjusted properly, this diagram shows why.

By twisting to open the car door, you negate most of the safety features of your car. There are times when a patient needs to be extricated from the vehicle; as an EMT and Paramedic in training, I will climb in the car with you and begin medical care. Most of the times it is not necessary to wait for a patient to be fully extricated before starting care.
posted by JujuB at 5:51 PM on May 18, 2013


FWIW my airbags didn't open in my accident, and I've heard that airbags opening is not always a good thing.

Airbags keep you from hitting the wheel/dash, but if you're being hit from behind your reaction is going to be to sink back into your seat, not to rocket forward. (Also, having an airbag go off is a lot like being shot in the face with a 12 ga. shotgun loaded with a pillow. It's better than being shot in the face with a 12 ga. shotgun loaded with a steering column and windshield, but you won't confuse it with fun.)

To be honest, unless you're being hit from the side (where the door is the only piece of armor your have) I'm not sure how likely it is that you won't be able to open your door afterwards. I was able to open mine while my hood had something like a 60° bend in it.
posted by Kid Charlemagne at 7:39 PM on May 18, 2013


When I see someone coming up too fast in my rear-view when I'm stopped, I take my foot off the brake to make the collision (if it happens) more elastic. Of course, that means I might end up rear-ending the guy in front, or if at the head of the queue, I might wind up out in the middle of the intersection, but I figure that's all better than absorbing the full force of the impact.

No way would I open the door -- as Mitheral points out, I want its structural support locked into place.

And note the one time I did get rear-ended while waiting at a light, I saw the guy coming, even heard his brakes squealing. When he hit me it was just a tap, but when the light changed I pulled into the cross street like a good motorist, expecting him to follow so we could discuss the incident. Instead, he just took off.
posted by Rash at 9:48 PM on May 18, 2013


Definitely keep the door shut. But I wonder something similar (if I may widen your question a bit to "what should you do" more generally.) When this happened to me (I saw it coming for what seemed like forever,) I instinctively leaned back against the seat and headrest, but also I took my foot off the brake. I don't know why I did that - would that make any sort of difference at all if my car could roll freely or not? In that case, the result was: car behind me - totalled; car in front of me that I got pushed into - totalled; my car - minor scratch on the rear bumper. Weird.
posted by ctmf at 11:21 PM on May 18, 2013


Of course, that means I might end up rear-ending the guy in front, or if at the head of the queue, I might wind up out in the middle of the intersection, but I figure that's all better than absorbing the full force of the impact.

The extreme acceleration that your body undergoes when you get rear ended is particularly BAD for you. You would want to minimize the amount of this acceleration by doing things to reduce the speed you end up at. Fancy new Mercedeses even have a system that automatically gets on the brakes when it senses an imminent rear-end collision.

Getting on the brakes will also help reduce the chance of a follow-on accident.
posted by ftm at 10:38 AM on May 19, 2013


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