By on August 8, 2019

lincoln-continental-2017-iihs-crash-test

It’s likely your average new car buyer can’t come close to guessing the number of airbags poised to deploy in their new ride. Gone are the days when Lee Iacocca would hit the airwaves, bragging about his company’s standard driver’s side airbags. New vehicles are festooned with then.

However, one particular airbag could be doing more harm than good, according to a study by the Insurance Institute for Highway Safety.

After looking at recorded “injuries” in more than 400 small- and moderate-overlap front crash tests, researchers at the institute turned the spotlight on a seldom-thought-of safety device: the knee airbag. While these types of crashes are most likely to lead to lower-leg injuries (read up on the Dodge Challenger if walking away from a crash is something you value), the presence of a cushion for that all-important leg joint didn’t do much to alleviate the risk of injury.

Surprisingly, the presence of knee airbags in some cases actually upped the risk of leg injury. The IIHS researchers then pored over real-world data to see if the same outcomes showed up in actual crashes.

From the IIHS:

Knee airbags had only a small effect on injury measures recorded by dummies in IIHS driver-side small overlap front and moderate overlap front crash tests. In the small overlap test, knee airbags were associated with increased injury risk for lower leg injuries and right femur injuries, though head injury risk was slightly reduced. The airbags had no effect on injury measures in the moderate overlap test.

In the analysis of real-world crashes, knee airbags reduced overall injury risk by half a percentage point, from 7.9 percent to 7.4 percent, but this result wasn’t statistically significant.

The institute suggests the proliferation of knee airbags is primarily aimed at helping manufacturers pass tests conducted with unbelted crash test dummies. In collisions where the occupant is not restrained, such an airbag might provale valuable. When you’re a loose pebble in a tin can, everything helps.

For secure front seat occupants, the value in having a knee airbag is much less clear.

“There are many different design strategies for protecting against the kind of leg and foot injuries that knee airbags are meant to address,” said Becky Mueller, IIHS senior research engineer and the study’s co-author, in a statement. “Other options may be just as, if not more, effective.”

[Image: IIHS]

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46 Comments on “The Airbag You Don’t Want? IIHS Cuts a Popular Safety Device Off at the Knees...”


  • avatar
    sgeffe

    I hope to heck that knee airbag in my new Accord doesn’t fire when I’m wearing shorts! Probably’ll end up with a nasty burn.

  • avatar
    thejohnnycanuck

    “When you’re a loose pebble in a tin can, everything helps.”

    Are there still that many idiots out there who don’t wear their seat belts?

    I guess it’s true, you really can’t fix stupid.

    • 0 avatar
      APaGttH

      I believe the last stat I saw on US seatbelt compliance was around 85%. Seatbelt laws interfere with Darwin and enable stupid people to breed, creating more stupid people. Those stupid people grow up to vote.

      If someone thinks it is their God-given right to go through the windshield in an accident, why should the government get in the way of culling the herd?

    • 0 avatar
      jmo

      “Are there still that many idiots out there who don’t wear their seat belts?”

      I don’t know where you live but if your area has a local newspaper web site it’s shocking how many times you’ll read, “The unbelted occupant was ejected from the vehicle and killed.” The saddest part is that a lot of the time it’s teens being stupid. You mean you didn’t think to belt up when you’re idiot friend was doing 100mph on a country road drunk as a skunk?

    • 0 avatar

      “Are there still that many idiots out there who don’t wear their seat belts?”

      No, their numbers are going down over time because of the law of natural selection.

      • 0 avatar
        -Nate

        “Are there still that many idiots out there who don’t wear their seat belts?”

        I still hear the old canard : ‘I’d rather be thrown clear in any crash’ ~ proving that stupid is clear to the bone .

        Those old horror filled driver’s ed films ? . I never got to see any, instead I worked on wrecked vehicles, cleaning them out before scavenging parts or rebuilding for resale .

        A grim task every new or stupid driver should be forced to endure .

        As far as Motocycles, the _only_ reason I’m still here is because my helmet, gloves, jacket and sturdy shoes .

        -Nate

        • 0 avatar
          Garak

          “As far as Motocycles, the _only_ reason I’m still here is because my helmet, gloves, jacket and sturdy shoes.”

          I’d have torn up my face, shattered my right foot, and gotten horrible road rash without proper protective gear. The crash happened at like 40 km/h. Never ride in regular clothes, kids, you’ll eventually regret it.

          • 0 avatar
            -Nate

            Those paper thin nazi ‘coal scuttle’ fake helmets aren’t much good either…..

            One of our 12 Y.O. Foster boys came it yesterday and began berating me for still riding Motos……

            He made up a joke :

            ‘Why did the man fly over the handlebars ?’

            A.: because he didn’t listen .

            -Nate

  • avatar
    Detroit-X

    AIRBAG TESTS AND RESULTS ARE FOR AN UNBELTED OCCUPANT.

    UNBELTED UNBELTED UNBELTED UNBELTED UNBELTED UNBELTED

    • 0 avatar
      Lorenzo

      Easy now! The tests are for BOTH belted and unbelted occupants, for comparison purposes.

      • 0 avatar
        Detroit-X

        In 25y I have never heard of belted occupants in a crash test. Do you have any links to read up on that?

        • 0 avatar
          PeriSoft

          Detroit-X

          youtube – watch?v=nnRIwQn9SA8

          …and every other IIHS and NCAP crash test video? They’re all belted.

          • 0 avatar
            Detroit-X

            I stand corrected corrected corrected corrected!

            In the industry, I’ve seen tests where the dummy is unbelted, but perhaps that is not standardized, and for is development, or some other purpose.

            So … for a belted dummy, I don’t see why knee airbags are needed, since if a person is belted, they should never move that far forward. Perhaps the knee airbags are for that special case of an unbelted occupant?

  • avatar
    Urlik

    Get rid of the testing requirement for unbelted occupants and let Darwin reign.

    • 0 avatar
      Detroit-X

      Agree completely, unless stupid adults are in charge of kids.

      • 0 avatar
        Lorenzo

        Having kids, or being responsible for kids, increases adult stupidity by an amazing amount. Just ask any 8-10 year old. By the second grade, any kid with normal intelligence realizes adults are irrational when it comes to kids.

        • 0 avatar
          Detroit-X

          Yep. I clearly remember expecting to die one night on M-52 south of Adrian because my father was driving drunk to the liquor store, for more. We came upon a T-bone accident that night in the pitch black. The first people at the scene asked if we had a flashlight. A year later, the Michigan State Police allowed my father to driver drunk, even after stopping him (custody issue). What a time it was.

      • 0 avatar
        cdotson

        Kids of stupid adults are likely to be stupid in their own time. Let’s not encourage stupid.

    • 0 avatar
      APaGttH

      I would generally agree – BUT.

      An unbelted rear-seat passenger can kill a belted front passenger if the seats are strong enough to take 250 pounds of human flesh slamming into the back of the seat.

      • 0 avatar
        Urlik

        No airbags for that in the back as of now APaGttH. Where as there are bags in the front as well as dual force bags only for unbelted occupants.

      • 0 avatar
        sgeffe

        I think I’ve heard of front-seat occupants being decapitated by unbelted rear-seat occupants during a crash. That true, or urban legend?

      • 0 avatar
        redgolf

        “An unbelted rear-seat passenger can kill a belted front passenger if the seats are strong enough to take 250 pounds of human flesh slamming into the back of the seat.”
        Also this – Defective seat backs. Sometimes a seat back cannot withstand the forces of an occupant’s pressing against it in a crash, and the seat will bend or break rearward into a reclined position. If a seat collapses backwards during a collision, the seat’s occupant is no longer protected by his seat belt or his air bag, and can be thrown into the back seat or even ejected through the rear of the vehicle. Therefore, a front seat occupant whose seat back fails during a collision is at risk of head injury, spinal injury (including paralysis) or even death. Front seat occupants are not the only passengers at risk of injury when a seat back fails. Children, even when properly riding in car seats, can be injured or killed when a failed front seat back or a front seat passenger slams into them during a collision. When a driver’s seat back fails, the driver can lose control of the vehicle and cause a multi-vehicle collision.

      • 0 avatar
        Detroit-X

        I ran across an accident scene in Colorado, where I later learned cargo from the rear killed the front seat occupants. A GMC Acadia.

  • avatar
    ToolGuy

    It is time to:

    – Optimize the occupant protection system for belted occupants.

    – Make non-use of the seat belt admissible in court.

    – Further optimize the belt system.

    – Add a Corvette-style cinch feature for the lap portion of the belt.

    • 0 avatar
      JoeBrick

      I traded my Datsun 280-Z because I couldn’t stand the automatic seat belt tighteners. In retro-spect, I should have just taken those damn things off and kept the car. And actually, it is my business whether or not I wear a seatbelt. BFYTW.

      • 0 avatar
        ToolGuy

        JoeBrick,

        The cinch feature I reference is optional – you can choose whether to engage it or not.

        You may also choose whether or not to wear your seatbelt. But if you expect society to cover part of the cost of your injuries, the fact that you were unbelted should be admissible in court.

        (Paging the moderator – LOL.)

      • 0 avatar
        dal20402

        “And actually, it is my business whether or not I wear a seatbelt. BFYTW.”

        It will also be your insurer’s business, when they deny your claim after your accident and you are stuck with a six-figure medical bill.

        • 0 avatar
          ajla

          “when they deny your claim after your accident”

          As I’m sure you are aware, that would depend on the state and situation involved.

          • 0 avatar
            dal20402

            Yes, and in places and with insurers where such a claim is not denied, the result is higher premiums for the rest of us.

      • 0 avatar
        bunkie

        Why does the expression “brick through a windshield” come to mind…

    • 0 avatar
      Sceptic

      If not using a seat belt is an offense. If it is a reason to deny insurance payment. Then it will be just as valid to apply the same logic to other cases.
      You like hamburgers, high fat diet? Offense. High risk of heart disease. No medical coverage for you.
      Multiple sex partners, promiscuous sex, homosexual? High risk of STD. No medical coverage.
      A female, can get pregnant(a choice!)? High cost to society in missed work, medical costs. No employment, high insurance premium for you.

      Where does this stop? These are serious constitutional issues and majority of
      passive complacent Americans just don’t care. Just observe how easily people gave up their rights after 9/11!

      PS I wear seat belts I feel more comfortable while driving in my seat that way.

      • 0 avatar
        BrentinWA

        This! Finally a comment from a thinking person. So many in our society are unaware of the “slippery slope” that comes with knee jerk reaction and applied legislation. I also find it ironic that most people who will state that seatbelt use be required for insurance payment on medical bills would flip their opinion if someone was seeking treatment for lung cancer after smoking marijuana for years.

  • avatar
    GMat

    Kilted by our own life saving devices

  • avatar
    dukeisduke

    I’ve wondered about the usefulness of knee airbags, especially if you’re restrained. I started wearing seatbelts when I was eleven, almost 50 years ago now. They’ve definitely saved my bacon a few times, like when I t-boned a full-size Chevy with a Fiat 124 sedan. I just put on the lap belt (was test driving it for a friend), but it made a difference.

  • avatar
    MRF 95 T-Bird

    The first generation 96-02 Kia Sportage two door convertible had a drivers side knee airbag. Considering that it wasn’t the safest vehicle I guess it helped in a crash or rollover.

    • 0 avatar
      slavuta

      I guess, you need to read a manual again. It has all the situations when airbag wouldn’t deploy. And rollover would definitely NOT deploy a knee airbag

  • avatar
    NeilM

    Never mind the knee airbag effectiveness; what I can get out of my head is where the left front wheel is ending up in the Lincoln pic at the top of this article. No airbag is going to save you from that.

  • avatar
    tankinbeans

    What kinds of injuries can occur when occupants have had knee replacement surgery? Does the force profile create its own possibility für injury?

    I know traditional airbags can cause issues for young children and people of short stature.


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