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Stages of a side-impact accident.

Crispin

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Oldish info now but always found it a fascinating read:

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.
 

Paul

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There is an even faster unit of time measurement........

Its the time taken from the traffic light going green to the driver behind you beepng his horn :cool:
 

Chris

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Well that's women drivers for you.

Oh come on - it's a joke. Who wasn't thinking that as a punch line? But surely, 300ms is not right? It could be weeks.

"What dent - I didn't do that. It was like that already. I've never loved you, I've been seeing your brother..."

Sorry got confused for a moment. Was this really a technical question? :roll:



Chris
 

Crispin

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I was reading an article in Car (SA Magazine) which was also telling about some new tech which, IIRC Toyota was introducing, which tightens up the seat belt, moves the head-rest and other bits and pieces when it decides, based on external senors, that it's about have a crash. Pretty nifty....

So, if you are driving along and the seat-belt tightens, pinch!
 

Chris

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How far in advance can it detect that and does it contact your insurance provider and up your premium and deduct the payment from your account all before the crash? Obviously there would be no refund if you managed to steer away and avoid the collision.

Chris
 

chadr

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Crispin said:
I was reading an article in Car (SA Magazine) which was also telling about some new tech which, IIRC Toyota was introducing, which tightens up the seat belt, moves the head-rest and other bits and pieces when it decides, based on external senors, that it's about have a crash. Pretty nifty....

So, if you are driving along and the seat-belt tightens, pinch!

MB have a system called "Neck-Pro Active" head restraints, which are available on S-CLASS and perhaps other models. They basically support the head in the event of an accident to avoid whip-lash.
With the new NECK-PRO head restraints, Mercedes-Benz is making a further important contribution to driver and passenger safety. The crash-responsive head restraints are now standard specification in the C-Class, CLK-Class, CLS-Class and E-Class.

The NECK-PRO head restraints are linked to an electronic control unit: if the sensor system detects a rear-end collision of a predefined degree of severity, it releases pre-tensioned springs inside the head restraints, causing it to move forward 40 millimetres and upwards by 30 millimetres. This happens in a split-second and has the effect of providing support for the heads of front seat occupants during the early stages of an accident. In this way, Mercedes-Benz has again improved the level of protection for the occupants in a rear-end collision and as a result, reduced the risk of whiplash injuries.
 
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Andrew Prince

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The sort of people that drive those Mercs are more prone to accidents and neck injuries (i.e. OLD) :lol: :lol: :lol:
 

pugwash

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i think you might find the real events with an 80 series go like:

0 milliseconds - An external object touches the driver’s door.
15 ms - Door begins to absorb part of the impact.
20 ms - External object begins to contact rock/tree slider .
27 ms - Impact velocity Reduced from 50km/h to 0km/h
30 ms - The Landcruiser has absorbed all crash energy. Occupant experiences maximum force equal to 1/2 times the force of gravity as the cruiser moves 1cm sideways.
Engineers classify crash as “complete”.
150-300 ms - Occupant becomes aware of collision.
500ms landcruiser drives off, little euro box turned into a little box of bits
 

Jon Wildsmith

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We noticed the noise rather than feeling any impact when a clio or something similar bounced off the side of my old 80 cutting through some back streets in Swindon a couple of years ago. The young girl driving had failed to notice she should have stopped at the end of the side street and just carried on. She was very lucky she ran into the side of me though because Ray was just a cars length behind so if she'd made the gap she'd have been flattened. The front seat passenger looked a bit white looking up at the front of Ray's 80 looming over them :mrgreen:
 

Rob

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pugwash said:
Occupant experiences maximum force equal to 1/2 times the force of gravity as the cruiser moves 1cm sideways.
sorry to get dull and technical but if the 80 comes to a halt faster than the eurobox from the same speed the g force which the occupants experience would be in the same order of magnitude greater than the eurobox (approximately) :ugeek:

EDIT: ah forgot about the mass of the object hitting the 80, so the deceleration is less than the above statement if the mass of the object hitting the 80 is the same as the eurobox.... like jons experience with the clio
 

pugwash

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ahh yes but you are not taking into account Mass

800kg v 4tonnes makes quite a big difference in F=MA!

although the A should be Decelreration!
 

Jon Wildsmith

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My very first accident was much more like the 1st post description but without the air bags bit because it was a while ago :lol: I think that's why I like cars with plenty of mass and width - to deal with side impacts so I don't get squashed again!
 

Crispin

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pugwash said:
i think you might find the real events with an 80 series go like:

0 milliseconds - An external object touches the driver’s door.
15 ms - Door begins to absorb part of the impact.
20 ms - External object begins to contact rock/tree slider .
27 ms - Impact velocity Reduced from 50km/h to 0km/h
30 ms - The Landcruiser has absorbed all crash energy. Occupant experiences maximum force equal to 1/2 times the force of gravity as the cruiser moves 1cm sideways.
Engineers classify crash as “complete”.
150-300 ms - Occupant becomes aware of collision.
500ms landcruiser drives off, little euro box turned into a little box of bits
:lol: :lol: :lol:
 

Andrew Prince

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Jon Wildsmith said:
My very first accident was much more like the 1st post description but without the air bags bit because it was a while ago :lol: I think that's why I like cars with plenty of mass and width - to deal with side impacts so I don't get squashed again!
Sounds like you've had your share of driving misfortunes then, Jon :cool: I know this thread is about side impacts but tell us about the fiesta you ran over when you skidded on black ice - did your old 80 have air-bags and did that impact set them off?
What was the relative damage between the <1t fiesta and a 3.5t 80?
 

adrianr

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Not sure about Jon but in 1995 a pal of mine was driving my 80, i was in the passenger seat.

he "tapped" a Nissan Micra at about 10 mph, at least a tap is was what it felt like to us.

Damage to Cruiser:
- 3 broken clips in the chrome strip on the bumper. about £6 from memory.

Reason for the contact:
- he said was thinking about something else, which was sweet of him since he was the "I have no money" kind of mate so I had to stand for the rather more extensive damage to the Micra.

Damage to Micra:
- replace tailgate
- replace window in same
- replace driver seat (it collapsed)
- replace under tailgate
- replace rear lamp cluster (not just the lens)


about £400, and one very upset lady who was not well pleased about being shot down the road as if from a catapult. :shock:
thankfully she was fine, and i had a pal nearby and we had her car all fixed up and back with her within 3 days.


Lessons learned:
- Dont let dizzy mates drive cruiser. Includes mates who CAN afford to pay for accidental destruction of other vehicles.
- If you cant stop - exit left (in this case there was a really wide flat grass verge and a low kerb would have been ideal, and we could have jumped the queue that was forming ahead of us ;)
- no need to brace for impact, we felt nothing
- micras are no where near as strong as cruiser (still like them though and we have 2 in the family - drivers of both under strict instructions to watch out for Landcruisers, well actually anything bigger than them, so thats pretty much everything on the road save a Smart car and a few others)
 

Jon Wildsmith

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I hit the back of the fiesta at an angle with the front left corner of the cruiser and it pushed the front left tyre off the bead so I had to change the wheel :( It was about 5:50am and no one came out so I had to just put a note under the wiper on what was left of the Fiesta and carry on down to the ELCO gathering on the plain I'd been heading for :D The back of the fiesta was pretty crushed and wouldn't have been repaired but I've no idea what the cost outcome was, I just handed the details over to my ins company.

EDIT: my 80 was a 94 so no airbags to worry about.

Related to relative mass, once when joining the M54 motorway in Telford heading towards Shrewsbury, I had a sort of side impact incident - the slip road goes from 2 down to 1 lane like a lot of slip roads but then the 1 lane carries on alongside the motorway for 1 junction as the A5 where I was getting off again. At the last minute an old bloke in a newish honda accord decide to drive round the outside of me and then cut across the front of me. Problem being he hadn't got much more than half way past me when he suddenly cut across so there I am driving down the road at about 60mph with this blasted honda across the front of my 80 with the old bloke staring at me wide eyed for a few seconds before it finaly span off up the grass verge to my left out of the way :roll: When the police arrived it was sort of funny because the honda was in a real mess half way up the embankment but all we could find on the 80 was a 3" scuff on the front drivers side tyre wall :lol:

I've found trees and rocks are more of a challenge :mrgreen:
 

pugwash

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had an accident in france whilst a passenger in a very well prepped 110- driving in carcassonne and hear a screech, leant forward to look in the mirror and felt a bit of a bump and a very loud bang- kid in a citroen zx had been leering at the local totty and slammed into the back of us at about 35 mph

the 110 had a scratched nato hitch and a brake pipe that made been moved 3-4mm.

the citroen had torpeod under the rear of the 110- it had been stopped by the nato hitch which had speared INTO the engine block- the big band (we think) was the nato hitch hitting a moving piston! Both wheels forcibly removed, winscreen smashed etc etc etc

it was quite amazing seeing what happens when a light box hits a heavy brick!
 

Chas

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pugwash said:
it was quite amazing seeing what happens when a light box hits a heavy brick!
Or a heavy brick hits a light box, I once ran into the rear of a Metro with my first Cruiser in heavy rain with disasterous results, for the Metro :shock: , it opened up like a banana being peeled :lol: , the roof went up, each rear wing went out, the tailgate went inside, all the Cruiser suffered was a bent bull bar, straightened by attaching a rope to something solid and reversing slowly :cool:
Chas
 
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