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Thread: Timeline of a Car Crash

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    wittycranium's Avatar
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    Default Timeline of a Car Crash

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    h3Car crash over before consciousness kicks in:/h3

    Timeline of a Car Crash - falcon crash testThis 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.





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