Car crash over before consciousness kicks in

This is a fascinating run down of an ‘anatomy of a crash’ from Australian car magazine Drive suggesting that the accident can be over before we’re even consciously aware of it happening.

This is a reconstruction of a crash involving a stationary Ford Falcon XT sedan being struck in the driver’s door by another vehicle travelling at 50 km/h.

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.

The video of the crash test, from which is the above is taken, is also available online.

As you can see, it’s a lab-based crash test and so doesn’t capture the messiness of many real world impacts.

I checked out their figure for conscious awareness kicking in at 150-300ms and it seems to be accurate and mostly taken from the work of neuroscientist Benjamin Libet.

There’s a good 2004 review article from the Archives of Neurology that actually cites 300ms as the start of conscious awareness, some other reviews cite 200ms as a ‘rule of thumb’ figure.

Link to Drive on ‘Anatomy of a Crash’ (<a href="http://www.sentientdevelopments.com/2009/02/will-you-perceive-event-that-kills-you.html
“>via Sentient Developments).
Link to paper on ‘Neuronal Mechanisms of Conscious Awareness’.

2 Comments

  1. Tom Ackroyd
    Posted February 25, 2009 at 1:21 am | Permalink

    True, but surely this is trivial. We sense events 150-300ms late *all the time*. This means that, while the accident has already happened, it makes no difference to any observer of that event. What the article and your post suggests, probably unintentionally, is that in a high speed crash we are not aware of anything happening until it’s “too late”. But of course our “rate of experience” varies little in relation to the speed at which events unfold. Doesn’t it?

  2. Ritika
    Posted November 16, 2009 at 4:26 am | Permalink

    Road safety first. This should be the priority of all the drivers to avoid accidents. I have found best gadgets to keep you safe in terms of road safety. First is No Nap . If you are feeling drowsy but needed to keep yourself on the road and just want to make it to your destination as soon as possible without causing a major accident. And you have tried all the un-effective strategies to keep you awake just like drinking 10 cups of coffee, blasting some punk music, or drinking some old stuff like energy drink this is the best gadget for you. The No Nap is a small, easy to use, device that will keep you and others safe during a long, drowsy drive. All you need to do is turn the device on, adjust the wake up angle switch, and place it behind your ear. Then when your head slumps forward as you begin to doze off behind the wheel, the No Nap produces a loud, powerful beeping noise that will snap you out of your snooze. It runs on low battery consumption, and its ergonomic design fits comfortably behind your ear. This gadget has been popular with truckers who spend long hours on the road and it could be useful for keeping many others safe on the highway as well. So why take a risk in driving you might not just save your life but start caring for others too


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