Near death experience

February 19, 2009 9:01 PM

Australian auto website offers anatomy of a crash-- a point by point account of what happens during an accident, up to and including the moment you realize it's happening.

"One way to appreciate the slowness of your perception is to compare it to the speed of mechanical devices. Take this incredible, sobering "anatomy of a crash"....With fine-grained temporal resolution, it analyzes what happens when a stationary Ford Falcon XT sedan is struck in the driver’s door by another vehicle traveling at 50 kilometers per hour" (via 3quarksdaily)

Of related interest: David Eagleman on whether our perception of time slows down during terrifying events (short answer: no) and how you would test this in the first place (short answer: strap a chronometer to your test subject and throw him off a building)

posted by puckish (15 comments total)

Very neat, thanks!
posted by turgid dahlia at 9:29 PM on February 19, 2009

"All this results in a crash where the occupants walk away."

I still remember a similar breakdown of events in drivers' ed back when crash protection was little more than as much metal as drivers could afford to put around themselves. That description ended with the steering column in your heart about the time you became aware of a collision....
posted by Kronos_to_Earth at 10:37 PM on February 19, 2009

Been there, done that. More than once.

The first time I don't remember anything except for what occurred several minutes after the fact.

The second time I remember hearing the front end crumple and watching the windshield spider exquisitely in what seemed like slow motion.

I guess it depends on how fast you are going, and if you can see it coming.

I rarely drive any more.
posted by moonbiter at 11:11 PM on February 19, 2009

Here's a video of the side impact crash test the anatomy of a crash is based on. Impressive when compared to not-so-safe cars like the Brilliant BS6 or this one.
posted by JonB at 11:30 PM on February 19, 2009

Very cool, I like this bit (emphasis mine):

30 ms - The Falcon has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.

The previous point was 3 ms before, and the subsequent event occurs 15 ms later. Must be bloody brief!
posted by kisch mokusch at 1:32 AM on February 20, 2009

So much for my "ducking out of the way" crash strategy.
posted by orme at 4:46 AM on February 20, 2009 [1 favorite]

With fine-grained temporal resolution, it analyzes what happens when a stationary Ford Falcon XT 1966 Beetle sedan is struck in the driver’s door by another vehicle traveling at 50 kilometers per hour:

0 milliseconds - An external object touches the driver’s door.
1 ms - The car’s door pressure sensor detects a pressure wave.
2 ms - An acceleration sensor in the C-pillar behind the rear door also detects a crash event.
2.5 ms - A sensor in the car’s centre detects crash vibrations.
5 ms - Car’s crash computer checks for insignificant crash events, such as a shopping trolley impact or incidental contact. It is still working out the severity of the crash. Door intrusion structure begins to absorb energy.
6.5 ms - Door pressure sensor registers peak pressures.
7 ms - Crash computer confirms a serious crash and calculates its actions.
8 ms - Computer sends a “fire” signal to side airbag. Meanwhile, B-pillar begins to crumple inwards and energy begins to transfer into cross-car load path beneath the occupant.
8.5 ms - Side airbag system fires.
15 ms - Roof begins to absorb part of the impact. Airbag bursts through seat foam and begins to fill.
17 ms - Cross-car load path and structure under rear seat reach maximum load.
Airbag covers occupant’s chest and begins to push the shoulder away from impact zone.
20 ms - Door and B-pillar begin to push on front seat. Airbag begins to push occupant’s chest away from the impact.
27 ms - Impact velocity has halved from 50 km/h to 23.5 km/h. A “pusher block” in the seat moves occupant’s pelvis away from impact zone. Airbag starts controlled deflation.
30 ms - The Falcon has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.
45 ms - Occupant and airbag move together with deforming side structure.
50 ms - Crash computer unlocks car’s doors. Passenger safety cell begins to rebound, pushing doors away from occupant.
70 ms - Airbag continues to deflate. Occupant moves back towards middle of car.
Engineers classify crash as “complete”.
150-300 ms - Occupant becomes aware of collision, or maybe dies.
posted by UbuRoivas at 4:52 AM on February 20, 2009 [3 favorites]

I hit a wall head on at ~40mph. I remember vividly seeing the wall in front of me, realizing that I was going to hit it and had just enough time to think "This is going to hurt."

And then I was sitting in the seat with the airbag already deflated thinking "that's it?" The crash itself was so fast it didn't even register. I was fine, only a little bruising where I hadn't taken my hand off the stick shift like an idiot but the speed of the thing was incredible.

Of course my first, critical instinct was to find my glasses, which had been knocked into the back seat intact. Obviously this was more important than little things like turning the engine off and getting out of the car. The violence of even that minor collision was startling in ways the driver safety videos tried but failed to convey. It just happened, inexorably.
posted by Skorgu at 4:53 AM on February 20, 2009

All I recall when my Honda Accord was t-boned by a Mack truck doing 60mph was a loud explosion.

I woke up in the ditch across the highway somewhere between 300,000ms and 600,000ms later.
posted by bwg at 4:57 AM on February 20, 2009

Note to self: don't buy a Chinese car. Jeez, I've seen accordions pack up less quickly. I least now I know where my recycled tin foil has gone.
posted by MuffinMan at 5:37 AM on February 20, 2009

When I had a head-on collision 15 years ago I felt I experienced everything .. I still vividly remember the roof crumpling up and seeing the other guy's airbag deploy (mine didn''t have one). Time really slowed down and I went from doing 60k to going backwards all in slow motion.
posted by saucysault at 8:36 AM on February 20, 2009

the last accident i was in involved a very large douglas fir tree. my friend was driving his mother's pickup truck, i in the passenger seat.

the first thing i remember was my friend looking at me and saying, "tell her you were driving!"
posted by klanawa at 9:00 AM on February 20, 2009

I remember seeing something like this in U.S. DOD Defensive Driving Course. IIRC, it said that somewhere around 1/2 second that the chrome has peeled from the front bumper and has started to embed iteslf 1/16" into the bark of a tree. Imagine that!
posted by winks007 at 9:43 AM on February 20, 2009

This seems accurate.

What I remember from having flipped my truck is:
1. Driving down hill at 45.
2. Glance to right to verify no one pulling out in front of me.
3. Glance to left to make sure nothing stupid is happening.
OMFG!
STUPID!
4. Brake, Steer, "Wow, that's a big SUV. And very white."
5. BANG
6. WTF? Weird...
7. Why is the dog laying on the ceiling?
8. Oh crap. Truck is upside down. I smell smoke. Must get out. Now.
9. (At this point someone poked their head under the tailgate and asked if I was alive - in retrospect, that's a pretty bad question to hear.) "Can I have a knife? I'm stuck."

1 to 2 took about 2 seconds. 3 - 6 took in total about another second. That includes me slamming the brakes, hitting the side of the SUV, and flipping into the air. 7 is about when the truck stopped sliding - after that time returned to normal.
posted by krisak at 7:26 PM on February 21, 2009

I feel sort of bad about how funny I found that Chinese car crashing.
posted by Uppity Pigeon #2 at 7:59 PM on February 21, 2009