4-5-6 pt belts and roll bars for street cars

[Andrie Hartanto]

I found this in one of the mailing list.
Which support what I've been saying about running a harness without a roll bar or cage.

http://www.nsxprime.com/forums/showthread.php?s=&threadid=2337&highlight=harness





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I faithfully transcribed one part of a 4 part document that Joe Marko
distributed at Tech Fest West in LA earlier this year. He did say that
he would like to put it up on his website. I have yet to see it. When
reading this it is apparent to me that there are some sentences that
don't make sense. And, I don't want to editorialize to correct them.
The few things in brackets are my comments.

Regards,
Marc

[Begin Joe Marko's document]

#2-Myth - Aftermarket 4-5-6-point harness belts should not be used in
cars
without roll bars.

A world-renowned panel of SAE vehicle safety experts from GM,
Daimler-Chrysler, Ford, University of Michigan, and a leading harness
belt manufacturer, were posed this question at the PRI show in
December 2002. They unanimously suggested that a properly installed
4-5-6-point harness belt system would significantly reduce the
likelihood of injury in a rollover accident when compared to a stock
factory 3-point system in vehicles without roll bars. In addition they
suggested that use of roll bars in primarily street driven cars could
greatly increase risk to driver and passengers in daily driving. Their
explanation for this is clear:

Most serious driver injury or fatality in rollover accidents (where
3-point factory systems are worn properly) occurs from head contact
with the door frame resulting when a car flips over and crashes on the
left edge of the roof. (Passenger injury occurs when to the right edge
of the roof).

Such rollovers result in loads of 10g to 35g deceleration to the body
eliminating the possibility of controlled "escape" by an occupant to
"duck" from the collapsing roof.

Such deceleration will typically eject the occupant partially from a
3-point factory belt.

The endless loop of webbing from the factory 3-point system will allow
a combination of released webbing from the endless loop of the webbing
at the shoulder that passes through the lap, and webbing elongation
that [when] combined will allow the body to move 50 to 100 mm upwards
in the seat. This can allow significant contact with the doorframe.

Deceleration forces to the head in contact with the door frame can
easily
exceed 300g. Properly installed "static" 4-5-6-point systems installed
to factory provided D and E, or C points [??] will significantly reduce
degree of contact with the door frame or even eliminate contact, as
there is minimal upper torso rotation. This configuration however
allows sufficient lateral movement to be moved as allowed by external
applied forces [??]. Factory seatbacks will flex a significant amount
under load giving more occupant headspace as the seatback is pushed
rearward.

4-5-6-point harness belts generally use 6% elongation webbing in the
lap belt
as opposed to 10-12% webbing in factory belts. This holds the occupant
much
tighter to the seat.

EMTs will confirm that very few serious injuries result from properly
restrained individuals in rollover accidents. Greater injury occurs
when occupants are not restrained properly and have fully or partially
come out of their harness. Schroth has had reports of several rollover
incidents where customers have contacted us and stated that the EMTs
credit the harness belts to [for] the lack of serious injury.

All vehicle safety systems are designed for 99 percentile accidents.
Properly
certified and installed 4-5-6-point harness belts significantly
increase
vehicle safety in 99% of likely accidents including rollovers. Any
safety system
including factory 3-point belts, airbags, traction control, etc. could
result
in greater injury in a 1% incident. The 99% rule is the best guideline
for all
safety equipment.

INSTALLING A ROLLBAR IN A VEHICLE THAT IS REGULARLY DRIVEN ON THE
STREET (A
DAILY DRIVER) SIGNIFICANTLY INCREASES THE LIKELIHOOD OF SEVERE HEAD
INJURY IN
EVEN A MINOR ACCIDENT FOR THE 99% OF THE TIME THAT THE CAR IS NOT ON
THE TRACK.
SINCE ROLLBARS ARE TYPICALLY INSTALLED WITHIN 6" OF THE BACK OF THE
HEADREST
THERE IS A HIGH LIKELIHOOD OF HEAD CONTACT WITH THE ROLLBAR IN EVEN A
MINOR
TRAFFIC ACCIDENT AS THE SEAT BACK FLEXES WHEN THE BODY REBOUNDS INTO
THE SEAT
BACK. ROLLBAR PADDING - EVEN HIGH DENSITY PADDING IS DESIGNED ONLY TO
WORK WITH
HELMETS AND PROVIDES VERY LITTLE PROTECTION TO AN UN-HELMETED HEAD.

MOST ACCIDENTS OCCUR ON THE STREET WITHIN 5 MILES OF HOME!

[End of Joe Marko's document]

 

[Taj]

I’ve been thinking about installing harness bar and belts. Are roll/harness bar and 4-5-6 point belts acceptable? You are still running into the possibility of a collapsed roof.

 

[sjs]

I’ve been thinking about installing harness bar and belts. Are roll/harness bar and 4-5-6 point belts acceptable? You are still running into the possibility of a collapsed roof.

Based on the above one would conclude that your best/safest overall choice is just that, a harness (not roll) bar and 4 or more point harness.

Thanks for sharing this Andrie. It is an interesting (and IMO logical) perspective on a topic about which some very credible people have long been adamant to the contrary.

 

[kenjiMR]

This is a very good post.

I wonder if the 99% theory will also applies on situations at the track as well assuming no projectiles are launched directly into the car but only rollover or front/side impact accidents.

Thanks Andrie.

I'll keep using my 3 point on the street and 4 point at the track.

 

[Lud]

There are a couple different messages in that post.

First there is the claim that a roll cage in a street car increases your chance of head injury on the street. This makes sense since you're not wearing a helmet and now have a big strong metal tubes running around your head. I don't think there is much debate on this point.

Second is the claim that 4-5-6 point belts increase safetly on the street in a car with no roll bar. This is the point that is argued. This message contains at best a fourth hand report of a discussion panel of people who are not even named. Specifically, it is a repost of something from a mailing list that is allegedly a typed version of a document handed out at "Tech Fest West" which was allegedly based on some guy named Joe Marko's recollection of a panel discussion by some unnamed people at the 2002 PRI show who it is claimed are automotive safety experts working for major auto manufacturers. Joe Marko, who Google suggests is president of the Boston chapter of BMWCCA, has yet to even post this document on his own website.

There are also problems with the contents of the document. First they discount the anecdotal crashes where not having a harness saved someone's life. Then they turn around and point out that Schroth had reports of several rollovers where the EMTs said the harnesses saved the driver. So anecdotal evidence in support of the claim is worthwhile, but anecdotal evidence against it is not?

At one point the articles says that a crash happens too fast for someone to "duck" a collapsing roof. This makes me question the whole document. Nobody "ducks" a collapsing roof in a roll-over. But if your body has some room to move laterally, your head can be pushed to the side by the collapsing roof instead of held in place by the harness.

The article ignores the difficulty of properly installing 4-5-6 point harnesses in many street cars, including the NSX. On the NSX you really need a racing seat in the car. With stock seats (even with a harness bar), the side bolsters make it virtually impossible to get a proper fit from the side belts, and you have to cut the seat bottom, drill the bottom of your car and use a backing plate to properly mount the 5th/6th point.

It also ignores aspects of using a harness on the street other than the actual crash. If you are wearing a racing harness correctly you cannot turn to look behind you. Your clothes will be wrinkled. Most people won't be able to reach a lot of stuff in your car, such as the stereo, heat or AC, etc. Stuff that doesn't matter at the track, but causes people to tend to wear harnesses too loose on the street in favor of comfort and convenience. Many people wear their stock 3-point belts too loosely as well, but the reduced stretch in the harness belts makes it that much more important to wear them tight.

And on the other side of the issue, it does not address other benefits you might get from a harness. For example, since harnesses hold you in the seat better, how often would they help you maintain control of a vehicle after it has gone off road in cases you might be too tossed around with a 3-point belt to keep control?

I am certainly not a safety expert or engineer and I am open to the idea that racing harnesses may be safer than stock belts on the street, but I would like to see a little more actual evidence supporting that idea. These are simply questions I have and my ideas may be completely wrong. I am not trying to give anyone advice here, just get answers to my own questions and (perhaps unfounded) concerns.

P.S. Thanks for the ride around Infineon Andrie! You are fast! Sorry to hear about the spun bearing at the end of the day, that sucks.

 

[Soichiro]

Joe Marko owns HMS Motorsports which distributes Schroth harness products in the northeast section of this country.

CAVEAT - HMS is also a HANS device dealer. I work at HANS.

 

[Andrie Hartanto]

Gary,

how bout posting HANS device video that they distributed with the purchase of the device. such as crash test numbers and forces and so forth.

 

[Taj]

Does anyone know if Schroth or any manufacturer makes any DOT approved 5 or 6 point harness?

 

[Soichiro]

Andrie please contact me. [email protected] or 770.457.1046