E91 - low speed crash and its consequence

[Toad]

Hi folks.

Just a small post regarding a low speed crash involving my 06 E91, but none the less somewhat more damaging than I would expect with a relatively new car.

Situation: Two lane elevated ramp heading towards a roundabout, outside temperature about -1 degrees Celsius, wet/icy/salted road (this happened in Norway and a lot of salt is used to prevent ice/slippery roads during the winter period) and traffic suddenly coming to a halt up front due to a car changing lanes abruptly without using blinkers.

Well, the two cars right in front of me managed to came to a halt and had just touched barely, and I unfortunately slid head on (breaking and swearing in approx 35 kmh – approx 22 mph) into the VW Polo in front (who in turn was pushed into a Saab 9-5).

Result: In my E91 both driver and passenger airbags was released, belt tensioners activated, windscreen smashed due to the passenger airbag lid being blown up, and one very scared Dalmatian in the back not knowing what the blast (airbags) and vicious smoke was all about.

My girlfriend and I can't even tell if we had contact the airbags - due to the low speed, as none of us were thrown much forward. But the loud noise from the airbags and the smoke filled compartment put us in a haze for a second or two, so we can’t really be sure…

OK, so the front bumper naturally got some punishment (and some small marks on the grille), but as far as I could see both headlights and bonnet were unharmed.

And the strangest thing, the frame/fittings on the large sunroof on the E91 broke! In trying to vent out the smoke and fumes from the airbags the whole front part of the sunroof slid out of its frame. It is solid glass and quite heavy, so a small shock is presumably enough to break the support - not very reassuring.

I'm I alone in thinking that the relatively large damage due to a crash in 35 km/h (22 mph) on the E91 is a bit on the heavy side here?

What puzzles me is the low threshold for the airbags to be released. The BMW dealer that took the car in couldn’t really answer that question, but thought that a crash in a lower speed like this shouldn’t call for the airbags to be activated.

And one other thing that is not well thought out in my opinion: After a small incident like this the car is still fully drivable, but due to the airbags being released the system goes into a safety mode and won’t allow the driver to start the engine. So we had to push the car as far as we could towards the concrete walls (this was an elevated road, ie not any curbs) and get a towing vehicle to get it to the dealer/workshop. I would feel much safer if I did not have to stand in the middle of rush hour traffic pushing a car, and then hang on and wait for the road assistance to arrive.

Well, the result from this low speed head-on crash is that the whole dash needs to be changed (I have the I-drive version), new steering wheel airbag, a new wind screen, a new sunroof frame, and of course the front bumper, grille and very likely some underlying parts in the front part of the car.

So, hadn’t the airbags been released (and we certainly did not need them at this low speed) all the interior and glass damage would have been history.
No word yet on the time it will take to get my BMW back, but I presume at least 3 or 4 weeks – perhaps more…

On the bright side, no damage to any living creature (two or four legged versions) and still having my trustworthy old E30 320i still around manage to get the transportation needs covered for the time being.

Regards
John

[Bandit335]

Hi folks.


On the bright side, no damage to any living creature (two or four legged versions) and still having my trustworthy old E30 320i still around manage to get the transportation needs covered for the time being.

Regards
John


Your last sentence is very telling an answers your question. While 22mph may not seem like a lot, I am sure that BMW and its legal team decided to be on the safe side. There have been posts like this before and you are probably correct in your assessment. In my opinion it's just a safety thing and it outweighed possibilities of a lawsuit in case you did get hurt. So this is purely a legal motive.

To give you an example: My friend while driving a small sedan rear ended a large SUV at only 5MPH! Supposedly the SUV driver's knee hit the steering wheel. The guy declined an ambulance and said he was fine. Two years later, the guy has since had multiple surgeries on his knees and has not been working. My friend's insurance settled the law suit on the first day of trial in the hundreds of thousands of dollars. That's the world we live in. BTW, the guy had preexisting injuries to that knee and they were the true cause of his injuries. Yet, the insurance company was worried that a jury might give the guy much more because the cop wrote in the accident report that he smelled some alcohol from my friend. No DUI involved.

[mryakan]

35kph is now low speed when it comes to a head on impact. There is a lot of intertia with the e91 mass at that speed. The whole idea is to prevent injury to you, something more important than preventing damage to the car, so the chasis and cage are made to deform as to suck in the most impact possible. Also airbags must deploy at around 14 mph or 23kph (http://en.wikipedia.org/wiki/Airbag), that is the US regulation, EU regulations are probably similar. If the car didn't sustain this damage, then you would have taken the full brunt of the impact and would have been in a hospital now instead of talking to us. Also the car not starting is a safety measure to ensure it doesn't catch fire. I believe it is some sort of relay switch that disconnects the battery and I am not sure if you can reset it yourself, but I suspect it is possible.
I'd say be glad no one gets hurt and maybe think about Snow tires if you didn't already have them. At 1C the summer tires take almost 50-60% more to stop and that would have saved you all that trouble. Sorry for your troubles and hopefully all will be ok soon and that's what insurance is for anyway, right?

[Critter7r]

If you don't think 22mph is a very "high speed" impact, try this... run as fast as your legs will allow straight into a brick wall (the the back of a car, whatever). My guess is that you'll be travelling less than 15mph and still break several bones. Or jump out of a car going 22mph, see how slow you think it is then! :D

P.S. What were you doing watching the speedo anyhow? You were supposed to be looking for a spot to swerve into!

[Toad]

35kph is now low speed when it comes to a head on impact. There is a lot of intertia with the e91 mass at that speed. The whole idea is to prevent injury to you, something more important than preventing damage to the car, so the chasis and cage are made to deform as to suck in the most impact possible. Also airbags must deploy at around 14 mph or 23kph (en.wikipedia.org/wiki/Airbag), that is the US regulation, EU regulations are probably similar. If the car didn't sustain this damage, then you would have taken the full brunt of the impact and would have been in a hospital now instead of talking to us. Also the car not starting is a safety measure to ensure it doesn't catch fire. I believe it is some sort of relay switch that disconnects the battery and I am not sure if you can reset it yourself, but I suspect it is possible.
I'd say be glad no one gets hurt and maybe think about Snow tires if you didn't already have them. At 1C the summer tires take almost 50-60% more to stop and that would have saved you all that trouble. Sorry for your troubles and hopefully all will be ok soon and that's what insurance is for anyway, right?

Well, interesting read on the history and facts behind airbags!

I'm not questioning whether airbags are good or not, or if a car should be deformed in crash - of course it should. The post was to point out the total damage of a to me a small crash in a not to high speed.

But to say that a 22mph crash without airbags would result in me being in hospital instead of here, is beyond me. With a belt on, an impact like this should not result in major injuries.

Of course I had winter/snow tires on. All Norwegians have a full set of winter/summer tires, and switch accordingly with the seasons.
(Or most do, its always the same every winter when the first snow has fallen during the night - hundreds of morons trying to get to work on summer tires and ending up in the ditch or sliding sideways into each other...)

And, no the battery was not disconnected, I had full power to all things electric. The start/stop button was just not responding, due to the "safety mode". I still don't think it's very safe to immobilize a car in the middle of traffic, no matter what caused it. Not being able to move a car out of the way is simply not my idea of progress safety-wise.



If you don't think 22mph is a very "high speed" impact, try this... run as fast as your legs will allow straight into a brick wall (the the back of a car, whatever). My guess is that you'll be travelling less than 15mph and still break several bones. Or jump out of a car going 22mph, see how slow you think it is then!

P.S. What were you doing watching the speedo anyhow? You were supposed to be looking for a spot to swerve into!

Right! And 3mph is enough to break an egg, but that doesn't really tell us much in this matter? We are strapped in a seat within a deformable cage, our body is not the first thing that hits this "wall".
I for one do not regard 22 mph as a high speed impact with a car, when people are normally travelling between 40-70 on most roads. Whether you agree or not, to me 20 mph is not very fast in a car...

On an elevated ramp there are no spots to swerve into I'm afraid - concrete rails on either side.
Ever tried turning quickly to either side on ice? Nothing much happens I'm afraid.

And of course I mostly have my eyes on the speedo when driving, it's such a nice red glowing dash in the new 3-series...

[Bandit335]

I'm not surprised that the airbags deployed as they did what they were designed to do. However, I agree with you that the moonroof thing is a bit odd and unexpected. I'm assuming you didn't have it opened at impact.

[cotmfk]

1st-as you said yourself-at least everyone is okay. I know I would be supremely pissed if I somehow caused harm to my wife or dog from driving.

2nd-it's a car. It will be replaced at some point.

So, since the 1st thing happened, life will be okay.

Sorry about you accident!

[Critter7r]

Mryakan is correct when he says the battery was disconnected as a result of the impact. But since there are more than one cable leading to/from the battery, the line that powers the interior electrics remains intact. The battery safety terminal physically severs the main battery cable feeding the fuel pump and starter by means of a pyrotechnic device similar to the seatbelt pretensioner. It fires a non-conductive piece of material to sever the cable and keep the two severed ends from contacting one another.





Right! And 3mph is enough to break an egg, but that doesn't really tell us much in this matter? We are strapped in a seat within a deformable cage, our body is not the first thing that hits this "wall".
I for one do not regard 22 mph as a high speed impact with a car, when people are normally travelling between 40-70 on most roads. Whether you agree or not, to me 20 mph is not very fast in a car...

On an elevated ramp there are no spots to swerve into I'm afraid - concrete rails on either side.
Ever tried turning quickly to either side on ice? Nothing much happens I'm afraid.

And of course I mostly have my eyes on the speedo when driving, it's such a nice red glowing dash in the new 3-series...


I was trying to make a parallel between the damage YOUR body would sustain by running into a wall vs. the damage the body of your car sustained in this "low speed" impact .... I wasn't comparing the damage your body would sustain running into a wall vs. the damage your body sustained while strapped into your car.

I agree with you that 22mph isn't really all that fast... until you start taking about hitting stuff. However, I think BMW (and other car mfr's) could raise the minimum airbag speed to 25 or 28 or so without suddenly starting to see carnage on the highway.

I've seen footage of the crash tests that are done with crash test dummies and all that, and those are typically done at 40mph. Those cars get F'ed up!!! And the dummies get all thrown around like, well like rag dolls.. anyhow, my point is just that by the time you get to 40mph, you really need those airbags. I'd guess that even at 30mph, they'd prove helpful. But at neaighborhood speeds of 25, maybe not so much.

[mryakan]

I agree with you that 22mph isn't really all that fast... until you start taking about hitting stuff. However, I think BMW (and other car mfr's) could raise the minimum airbag speed to 25 or 28 or so without suddenly starting to see carnage on the highway.

I've seen footage of the crash tests that are done with crash test dummies and all that, and those are typically done at 40mph. Those cars get F'ed up!!! And the dummies get all thrown around like, well like rag dolls.. anyhow, my point is just that by the time you get to 40mph, you really need those airbags. I'd guess that even at 30mph, they'd prove helpful. But at neaighborhood speeds of 25, maybe not so much.
Maybe we think not, but regulations state it has to be at a certain speed and for the US that speed is 14mph, probably similar regulation in EU. If BMW didn't comply, they wouldn't be able to homologate and sell the cars.

[Critter7r]

14?? Really, that low? I knew there were regulations, just not that overprotective! I really think that the seat belt and pretensioners would do the trick of keeping occupants safe up to 25mph. Blowing an airbag at 14mph seems like overkill.

[mryakan]

According to the Wikipedia link I posted:
Triggering conditions

Airbags are designed to deploy in frontal and near-frontal collisions more severe than a threshold defined by the regulations governing vehicle construction in whatever particular market the vehicle is intended for. U.S. regulations require deployment in crashes at least equivalent in deceleration to a 23 km/h (14 mph) barrier collision, or similarly, striking a parked car of similar size across the full front of each vehicle at about twice the speed. International ECE regulations are performance-based, rather than technology-based, so airbag deployment threshold is a function of overall vehicle design.

[LuvMyE92]

According to the Wikipedia link I posted:
U.S. regulations require deployment in crashes at least equivalent in deceleration to a 23 km/h (14 mph) barrier collision

Wow. I had no idea.

Saw a POS Taurus in a parking lot at lunch ... also a minor front-end collision, bumper and hood lightly damaged, but both airbags deployed and windshield broken on passenger side. No doubt it will be totalled, as one airbag costs more than that car is worth. I was wondering why the light damage, now I know why.

I'm all for having the car sacrifice itself for me, but if the seat belts are fastened, I would expect something closer to 35 MPH for deployment, not 14.

Hey - how was the doggie? Was he thrown forward by the impact, or did you have him properly restrained? And if so, how'd you manage that? :)

[Toad]

Hi folks.

Long time since I last was logged on, so Happy new year and so forth...

The doggie was fine, but of course a bit startled by the loud explosion from the airbags and all the fumes/smoke. Even though she (Its a 30kg two year old dalmation btw) has a dogcage in the rear compartment, the small impact pressed her forwards and shook her up a bit. She is now somewhat more reluctant getting into the car, and puts her tail between her legs to show this is not preferable. But after the hatch is down and we get the car moving, everything seems back to normal.

Thanks for your concern :-)

Regards John

BTW: I got the car back after a long 5 weeks as there was a lot of people bumping into each other in Norway that week, and therefore long waiting times on repairs. The total cost was about $14 000 (covered by insurance), which is a hefty amount considering a 22mph crash. But keep in mind that the parts and labour here are probably double the US price or thereabout.

[sor]

I'm not sure what to think. My instinct says that hitting an immobile object at 60mph is almost guaranteed death, and 35mph is a pretty major impact that everyone should survive if wearing seatbelts, maybe a broken bone or major bruising. Even though it's probably a log scale, I'd at least expect that ~25mph into an immobile object would be classified as 'about as fast as you can hit something and expect to walk away without any injuries'. Of course that other thing being a car absorbs some as well.

[markitzero]

Just a thought here but in trying to think about why the car would react that way the thought of brake pedal position came into my mind. Is it possible since you were on snow/ice and probably had your foot to the floor pressing down the brake trying to stop that that car thought you were stopping harder than you actually were? Just a thought.

[Critter7r]

The car doesn't "think" that much. It doesn't speculate that "since you're pushing really hard on the pedal, we must be trying to stop really fast, and since we're not slowing down as quickly as you pressing really hard on the pedal would suggest, then this is probably gonna be a really bad impact, so I'll just deploy my airbags just in case", even though they're only going 20mph and headed for a hay bale. It relies on wheel speeds, steering angle inputs and the inertia sensor to decide how to handle the impact.

Oh, and interesting bit... you can be going faster than 14mph and hit something and have the airbags not deploy. It's not a speed-dependent deplyment of the airbags, it's force-dependent. I know speed affect the force of a crash, but just wanted to throw out there that the deployment speed isn't etched in stone.

[mryakan]

The car doesn't "think" that much. It doesn't speculate that "since you're pushing really hard on the pedal, we must be trying to stop really fast, and since we're not slowing down as quickly as you pressing really hard on the pedal would suggest, then this is probably gonna be a really bad impact, so I'll just deploy my airbags just in case", even though they're only going 20mph and headed for a hay bale. It relies on wheel speeds, steering angle inputs and the inertia sensor to decide how to
Correct, but just to clarify a bit, the car does measure how hard you are braking but only uses that for the adaptive brake lights, i.e. to illuminate the additional brake lamps.