I used to wear a helmet while commuting in the DC area. I think I was the only one. I do wonder whether it might increase my risk of neck injury, because it's difficult to find a helmet that doesn't push your head too far forward, especially with the new car seat designs that all put the whiplash backrest too far forward for comfort.
In a small town, it's more of an issue, because people will recognize you. But on the beltway of a major city, who cares? If they think I'm crazy, they'll just give me more space.
I stopped because I decided it was more important to wear a painter's respirator when driving on the DC beltway. This greatly reduced the number of headaches I got while driving. It's a little awkward to wear both.
I sent the Crasche folks an email asking for data documenting the performance of their product. I received the following results as part of a brochure:
LACROSSE CROSS-IMPACT TEST RESULTS (these appear to be stick-to-head):
Sample # Impact Location Cross Velocity (MPH) Severity Index Peak G
Bare Headform Side 38.19 1051 188
Size Small Side 39.94 68 49
Size Large Side 38.64 8 24
LACROSSE BALL IMPACT TEST RESULTS (these appear to be ball-to-head):
Sample # Impact Location Ball Velocity (MPH) Severity Index Peak G
Crosse BXX 1 68.34 278 179
Crosse BXX 2 69.3 208 146
Crosse BXX 3 70.75 294 186
The following sentence was also included in the reply: "Note - these tests are for impact coming onto the head. In a drop test, which simulates a head on collision, a 9 mph event showed an impact reduction of about 25 %."
For reference, I remember reading somewhere that football helmets tend to increase impact duration from about 3 ms to about 8 ms. Assuming uniform force distribution over the duration of the impact, this amounts to ~60% reduction in peak acceleration (over whatever force domain that acceleration is correct for.) Crasche seems to guard effectively against forces similar to that of ...
I've looked up a few studies over the past few months in an attempt to understand direct causes of TBI and what kind of accelerations are "safe" - those under which a TBI (or diffuse axonal injury, DAI) is unlikely to occur, and to get a sense of what types of activities different accelerations correspond to. I'm dumping some info below without many citations as it's much lower effort than the alternative. If there's anything in particular that one is interested in, I may be able to find the relevant article. if you see anything that is wrong, please let me know.
TBIs appear to be caused by a combination of linear and rotational acceleration; these appear to cause injury via different mechanisms. Linear force/acceleration appears to create a high-pressure volume on the side of impact and a low-pressure volume on the opposite side of the head, with injuries possibly resulting from either. Rotational acceleration can, broadly speaking, cause brain tissues to stretch and twist in a way that they're not resilient to. However, this only appears to cause direct damage in the most severe of cases. In most cases, the majority of damage appears to be caused by a chemical cascade
Hmm.. wait a tic. Helmets absorb shock if your head hits something. On the motorcycle that's pretty much anything around me. But in the car, what exactly can my head hit?
I drive a recent model vehicle, and there's at least two* airbags around the driver. I can't think of any unprotected objects that my head could strike, that a helmet would help deal with. Plus if I wear a helmet, the added mass my neck supports is going to make it more likely to suffer whiplash, surely?
Not to mention that helmets seem to be designed to stop large accelerations over very short distances (i.e. soft-ish foam a couple of cm thick) whereas airbags are designed to act gently over much longer distances (a pre-perforated membrane that absorbs the blow and deforms over, I'm guessing like 20cm?)
I'm guessing that racing drivers wear helmets because in racing conditions debris is more likely to enter the car, the driver be thrown out of the vehicle, or the car will be deformed/destroyed when struck by another race car at 200km/h. Also the balaclava has a role to mitigating fire/burn risk from fuel spills.
I'm also sign(ing) up for cryonics, and want to make darn sure the lump of tissue between my ears isn't...
OK, so 42k injuries/9k deaths is sobering, but does it justify wearing a driving helmet? I've been curious about this topic and also walking helmets for a while and now that I have my own car again (ironically, given the datasets here, an old 2000 car), the topic of reducing car risks is also of some personal relevance. I'm going to give a stab at a quick and dirty decision analysis here to get an idea of how the case for driving helmets look.
First, we want to convert the absolute numbers to a probability of injury/death per mile driven:
in 2001, the American population was 284,970,000 (note that injuries/deaths also happen to people who are not the driver, and most people spend a fair amount of time in a car, one way or another), so that's an average annual mileage of 9,018 which sounds pretty reasonable So:
deaths: 8819 / 2569980000000 = mortality risk of 3.431544214e-09 per mile driven
How much do these helmets reduce risk and how much do they cost to buy & use? That's tricky to answer, but maybe some bounds will be helpful.
\$685 in present value is roughly equivalent to \$27 spent each year over the next 50 years, discounting at 3% (sum(sapply(1:50, function(t) { 27 * 0.97^t }))). So even something which reduced your car TBI risk to zero would not be worth paying more than \$27 each year for the rest of your life.
The mentioned helmets all sound like they only reduce acceleration or energy somewhat, and Crasche is quoted by Dorikka as estimating a 25% reduction in impact (which translates to an unknown reduction in TBI risk); another quote claims seatbelts reduce death/injury by ~50%. Let's be extremely optimistic and go with the latter, that our TBI risk falls by 50% using a Crasche helmet.
Then the gain from a Crasche helmet is 685 * 0.5 = \$342.
The cost of the Crasche helmet is ~\$30, leaving \$312. Let's assume there's never any replacements and we just need to consider the annual hassle of wearing it. Working backwards again, that leaves room for an annual cost of no more than ~\$12.3, which is small. I drive maybe thrice a week, so the per-trip cost of...
Good suggestion. I'm a cyclist and sometimes I walk around wearing my bike helmet. Some people give me funny looks, but I don't care. To regularly wear helmets, you have to recognize that avoiding TBI is more important than looking slightly silly or messing up your hair. Unfortunately most people don't get this. I think if helmets become more popular people will find that they don't actually mind the look, as you suggested in another comment.
Risk compensation is one potential problem with wearing a helmet. An example was mentioned in the original post: drivers passing cyclists who wear helmets closer. Also concerning is that cyclists ride more dangerously if they wear helmets (here's an article which I haven't read in full, but it discusses this issue). I imagine seat belts have a similar effect, as might drivers wearing helmets. Based on this idea backwards, I've read a proposal to add a spike to steering wheels to reduce dangerous driving.
Also worth noting is that avoiding long commutes and drives improves safety. Risk (probably) increases monotonically with duration.
One last suggestion would be to drive with a dashcam to make yourself slightly safer. I ride my bike with a very obvious helmet cam and I have observed that some drivers seem to drive safer around me when they notice it. I'm recording them, so if they make a bad move they'll be much worse off in court. I also think the camera makes me ride safer for the same reasons.
When I looked into this a few years ago I turned up Prevention of Head Injuries to Car Occupants: An Investigation of Interior Padding Options (McLean et. al. 1997). The improvement in interior padding and airbags since 1997 is probably enough to bring the benefit of a bicycle-style helmet down to just a few percent injury reduction.
But even assuming its as high as 10%, Nick Beckstead wrote:
...You allegedly get 1 micromort from driving 230 miles. Say that takes 4 hours, and say you get to reduce 10% of that by wearing the helmet. Then wearing a helmet for
I don't believe Nick's introspection here. $1/hour may sound plausible considered as a single choice for 1 hour, but not repeated, as it would be, over a lifetime: if you spend 3 hours a day in a car (which I have for a large period of my life), then he's willing to pay 3 * 365 = $1.1k a year or easily $50k over a lifetime to not wear a helmet? To put this in further perspective, the median American household's income is around that; so by claiming $1/hr, he is implicitly claiming other things like 'if a law were passed mandating wearing a helmet, I and my household would gladly labor like a slave for a year in exchange for an exemption', and so on and so forth. (You can quibble about things like discounting and Nick's probable above-median income and how many hours he actually spends in a car but still - $1/hr is actually quite a bit!)
Further, realistically, habituation and the hedonic treadmill means he would very quickly get used to it as a habit and eventually even come to expect it - like people get used to yarmulkes or old-timey men felt naked without their hats or the deaf/hearing-impaired get so used to their hearing-aids that they forget they are wearing them or how orthod...
1) I get the impression that most people do most of their driving alone. And of the people in the car with you, it's mostly pretty close friends/family, whom you presumably are pretty comfortable around. As for random people seeing you through the window, I wouldn't think that that'd be too embarrassing, given that it's so fleeting and that you'll never see them again. So all in all, I don't see that there's too big a downside. Maybe it's just because it leads to the self-narrative of "I'm a weirdo"?
I happen to take great joy in being contrarian in rational ways haha. So if I drove I'd totally do this!
2) Different way of looking at it (for parents) - would you chose to put a helmet on your child?
The numbers of traumatic brain injury (TBI) cases caused by falls are of about the same magnitude as TBI caused by motor vehicle accidents (CDC data, the relative frequency depends on age).
Would you recommend putting on a helmet as soon as you get out of bed in the morning for people in their 40s and older?
Per unit of time, I suspect you are much more likely to get a TBI while in a car than when awake but not in a car. I intend to wear my helmet in the winter when I go on long walks. I suspect that we would be better off if there was a social norm of everyone wearing helmets all the time. I have considered whether I should wear my helmet when I'm at home. (I'm over 40.) If the helmet was invisible I would wear it all the time.
why are bathtubs made of ceramic, instead of rubber or something soft?
My guess would be maintenance -- cleaning soft surfaces is difficult. Moreover, wet rubber is very slippery so it will have to be textured and that will make it basically impossible to get clean.
An alternative might be removable soft bumpers.
Was looking at this in the past, a couple of thoughts. 1. Some articles seem to indicate that repetitive impacts as small as 10g may have cumulative effect. By increasing the effective diameter of the skull, helmets may increase thr likelihood of impact by reducing the necessary angular displacement for the head ro collide with back of seat. As materials of many helmets are tuned for more severe impacts, they may not offer meaningful protection in this domain. 2. Do helmets reduce peripheral vision?
There are so many variables here. I think most people underestimate the violence involved in a high speed motor vehicle crash. Years ago, I was involved in EMS and responded to a lot of crashes. If we eliminate a) crashes without seatbelts worn (1), and b) crashes without frontal airbags (cars without frontal airbags are relatively uncommon these days, I'd say that most survivable TBIs were caused by either a) side impacts, with the head hitting the window glass, or b) the airbag itself (2). Of those two, the low-to-intermediate-speed side impact is the on...
The Crasche hat (at least the version I got, medium of the normal version) was only partly-assembled.
With the inserts in, how heavy is this and how small does it fold up? I cycle, and one thing keeping me from wearing a helmet is that I have no easy way to carry one. If I could just keep this in my jacket pocket, there's a decent chance I'd usually wear it.
Would it be too much trouble to ask you to update the top post with some of the information in the comments? Thanks.
How about wearing a massage vest while walking around. The obvious thing is, it's weird. From experience, actually, the helmet may scrape the roof of your car.
Are there any good massage clothing? The cochrane review on spinal manipulation says it's not better than exercise therapy or massage for chronic lower back pain. Massage costs add up, so I'm wondering what some good options are. Suppose I can solve my 'I'm cold' problem and 'I want a massage problem at once' without adding a 'where do I store this massage item' problem since I already have a wardrob...
I'm curious about liability risks that may accrue to the very lonely trendsetters who try it.
In my imagination, there's a terrible accident that leaves someone other than the helmet-wearer paralyzed or dead, and investigators are surprised to see that one driver was wearing... a helmet?? It's almost like he knew he was going to get into an accident -- perhaps even intended to. Certainly, that's what people would think reading the articles about it. Perhaps a jury would, as well.
Even a weaker version of that argument could be damaging; anti-lock breaks ar...
Thanks for posting this - I'm in a cold climate and have been looking for a beanie with head protection built in. One question - is there a noticeable hard shell under the fabric to the touch?
I've been wanting to get a hat with d3o in it, but I haven't been able to find anything after their announcement a few years ago. Anyone know anything about that?
Given that wearing a helmet likely makes you engage in more dangerous driven habits just as wearing a seatbelt does. It's an effect worth to keep in mind. I also don't know how much added benefit this provides over a simple airbag.
Bulletproof vests have anecdotally saved police officers from car accidents as well.
Seems like the sort of thing you might successfully convince new teen drivers to do despite the weird factor (since they're the highest risk demographic).
Edit: If the hats aren't extremely uncomfortable, might also be good fall protection for the elderly...
A 2006 study showed that “280,000 people in the U.S. receive a motor vehicle induced traumatic brain injury every year” so you would think that wearing a helmet while driving would be commonplace. Race car drivers wear helmets. But since almost no one wears a helmet while driving a regular car, you probably fear that if you wore one you would look silly, attract the notice of the police for driving while weird, or the attention of another driver who took your safety attire as a challenge. (Car drivers are more likely to hit bicyclists who wear helmets.)
The $30+shipping Crasche hat is designed for people who should wear a helmet but don’t. It looks like a ski cap, but contains concealed lightweight protective material. People who have signed up for cryonics, such as myself, would get an especially high expected benefit from using a driving helmet because we very much want our brains to “survive” even a “fatal” crash. I have been using a Crasche hat for about a week.