Disturbing RF crashtest videos

lenats31

New member
It looks like a good amount of the "research" cited on that page is that ISOFIX means that the seat is more likely to be installed correctly. The vast majority of users on the site can install car seats correctly with a seat belt. I've seen LATCH just as misused at a seat belt, so simply saying it's more likely to be used correctly doesn't hold any value IMHO.

There is proof of this statement about isofix. Isofix is a rigid system whereas LATCH is flexiable with belts. rate of incorrect fitment of isofix seats in Europe is 2-4%. That means 96-98% get fitted correctly. So isofix does add safety. However if you meassure a correctly installed beltfitted seat with an isofix seat - there is no difference other than perhaps some in side impacts.
 
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lenats31

New member
Your so-called expert seems to be neglecting the fact that the vehicle designers included seat belt stretch when they designed the vehicle. Seat belts are supposed to stretch, as it does increase ride down time. By bracing against a rigid structure such as the dash, you are all but eliminating that component of the vehicle's designed safety system.

Seat belts are supposed to stretch. They could make them with no stretch, or much less stretch, but they don't for a reason. If you look closely at a seat belt, you will see that it is made up of diagonally woven fibers. It is this diagonal weave that gives the seat belt its stretch. If the fibers ran the length of the belt, it would have much less stretch and the passenger would be more tightly coupled to the vehicle chassis. Coupling to the chassis is beneficial to a degree, but there comes a point where there needs to be some give. Seat belt design has accommodated this, by balancing tightly restraining the occupant and also stretching to allow more ride down time.

LATCH/UAS/ISOFIX belts and the internal harnesses on child restraints are also designed the same way. Some stretch is good.

Your expert mentions that many/most forward facing seats exceed the 550 mm standard limit for forward motion. If this is true, how are these seats legal? I know that in the US and Canada, any seat that is found to not comply with the standard would be recalled.

It is also worth noting that the child is NOT "cruis[ing], motion unchecked, forward in space" unless the seat and/or harness were too loose to begin with. If the seat was properly installed with a tight belt, and the harness was properly tightened, the motion is being checked by the seat belt and harness, which are stretching as designed to give the child more time to slow down.

Your expert also touts the tighter attachment of rigid ISOFIX. Again, he is neglecting that many seat manufacturers have designed a crumple zone of sorts into their rigid ISOFIX, because some give is desirable. The stretch of the webbing that was lost is replaced by a crumple zone. If the best performance was to be had by coupling the dummy to the chassis as tightly as possible, why would they intentionally partially de-couple them?

In the US, historically our seats have been made out of flexible plastics. Now we are seeing a trend towards metal frames and metal reinforcement, and at the same time we are hearing from the manufacturers that they are having to add other design components to the seat because the seat is too rigid. Too rigid, no flex, transfers too much energy to the child. And that is exactly what I was talking about earlier, when I said that watching a video doesn't tell the whole story - what were the injury measures experienced by these dummies? I'm sure that in the prototype stage, when these metal-reinforced seats were too stiff and were passing too much energy to the child, the crash test looked just fine but yet the dummies had extreme injuries.

I would be a lot more carefull with making such a statement, because you have NO IDEA who he is. I do.
 

Admin

Admin - Webmaster
This is a quote from a very knowlegable professional, named Robert Bell who has been working in the field for 30 + years. Questioned by a blogger which child seat configuration is the safest here's what he says:

"Content Removed by Admin".

I have received a complaint that this material may be copyrighted. If you prefer, you may quote a snipped of relevant content accompanied by a reference to the source or a link. If you would like to copy the entire work, please obtain permission from the author.

If you believe this work is in the public domain, you may contact me via private message before re-posting. Thank you!

Relevant to the conversation, I note that similar threads on this topic have referred to "experts". Not all claimed experts are actually experts. Even if someone is an expert with credentials to prove it, that doesn't mean they are always right or even that they always agree with other experts in the same field. Plus, it's quite easy to take the comments of an expert out-of-context or to extrapolate things that may not be true, even when citing peer-reviewed studies in legitimate journals and publications. Compounding these issues are language and cultural impediments when discussing international issues that may apply to one region, but not directly to another. Without having the actual expert available to contribute to this debate, I suggest that it is very difficult to determine their opinion on topics that vary, even slightly, from the topic they may have discussed in public (or private) elsewhere.
 

snowbird25ca

Moderator - CPST Instructor
I would be a lot more carefull with making such a statement, because you have NO IDEA who he is. I do.

Knowing an expert doesn't make them right about everything. Nobody ever knows everything and the thing about science is it's constantly evolving and changing - understanding crash dynamics is very much a science because as vehicle designs continue to change it will continue to influence how a seat interacts with the vehicle.

Nothing is set in stone other than basic physics - you can't change physics, but as car seats change and vehicles change, so too does knowledge and experience. Experts don't know everything no matter who they are - and they should know it.

I heard a quote from someone once who is considered an expert on the human brain. He stated that he knew everything that was known about the human brain, but that he only knew 1% of what there was to know.

People can speak based on current knowledge and past experience, but that doesn't mean things are universally true when you change variables - experts are humans and fallible too and discussion only benefits people. And knowing someone really doesn't change the nature of their training or expertise - it simply creates more loyalty to their point of view and perhaps hesitation to consider other information and viewpoints. Not saying this is the case with you - just saying it can happen with some people. :shrug-shoulders:
 
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lenats31

New member
Please consider this:


There are people who have been working in the child car safety business for many years - incl. "The So-Called Expert" mentioned here. These people do most likely have way more knowledge about the subject than any of us inhere.
I personally would not rip their advice ans information apart, which often happens

Also the user who has provided the info has spent time and effort doing it because someone else asked for it.
 

Pixels

New member
I would be a lot more carefull with making such a statement, because you have NO IDEA who he is. I do.

Are you threatening me???

Frankly, I don't care who he is. Nor do I care that you know who he is. I looked at his arguments and found many of them seriously lacking. I rebutted using logic. If you don't agree, then fine, that's your opinion and you are entitled to it. Feel free to rebut my arguments using logic or additional sources.

I have received a complaint that this material may be copyrighted. If you prefer, you may quote a snipped of relevant content accompanied by a reference to the source or a link. If you would like to copy the entire work, please obtain permission from the author.

If you believe this work is in the public domain, you may contact me via private message before re-posting. Thank you!

The removed content is viewable at http://www.sikkerautostol.dk/2010/09/isofix-vs-bilseleseatbelt/ for anyone who would like to read it.
 

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