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How well do cars do in crash tests they're not optimized for?

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Re: How well do cars do in crash tests they're not optimized for?

#151

Post by colechristensen »

ryanianian wrote: post #52
wscott wrote: post #30

The article reminds me of a story from a friend that was an engineer at a major water heater company. Modern electric water heaters are already fairly efficient, but every model gets tested by the government to be given an efficiency rating. The test consists of replacing the anode with a rod that has a series of temperature probes to measure the water at different levels in the water heater. Since water would form l…

Isn't this a symptom of the exact testing procedure being a white box that rarely changes? Many students would score 100% on the ACT if the entire question and answer set were widely published. Also that seems like a silly test. Couldn't you just measure the differential after mixing? TFA also mentions it, but noise is also a factor. For the water-heater example, the limited number of probes introduces a known amount…

It means the test procedure has vulnerabilities which need to be patched.

Re: How well do cars do in crash tests they're not optimized for?

#153

Post by csours »

mumblemumble wrote: post #132

Somewhat related anecdote, related to me by an acquaintance who works at a major US crash testing facility: I don't know about now, but, once upon a time, not too long ago, US safety standards included crash tests where the dummies were not wearing seat belts. This naturally leads to cars sold in the US having air bags that are tuned slightly differently, so that they are less likely to cause injuries to people not w…

As far as I know, this is still the case. A significant minority of people in the US do not wear seat belts; thus the timing on airbags has to accommodate this, or the airbags themselves would cause injury.

Re: How well do cars do in crash tests they're not optimized for?

#154

Post by zodiac »

nimih wrote: post #139
Daneel_ wrote: post #117

Earlier quoted context omitted.

I would imagine that it’s not a typo. In a car you have a big shell around you to protect against the environment. While walking or cycling you’re far more prone to be injured by the world - a branch could fall on you, a car could hit you, another person could hit you, you could trip, slip or lose balance, etc. Being inside a big metal shell that can’t fall over and with active safety measures is a great place to be,…

On the other hand, when I'm cycling, I'm typically not moving at >15 mph or so. When I'm walking, reduce that to 3mph. That seems like it would do a lot to counteract the car's crumple zones and airbags in terms of severity of injury. In fact, once you take into account severity, the GP's claim seems extremely suspect: maybe the chance of any injury on a bike or by foot is higher, but I'd be skeptical of claims that…

You can cycle at 15mph and have a car crash into you at a much higher speed

Re: How well do cars do in crash tests they're not optimized for?

#155

Post by dharmab »

ryanianian wrote: post #52
wscott wrote: post #30

The article reminds me of a story from a friend that was an engineer at a major water heater company. Modern electric water heaters are already fairly efficient, but every model gets tested by the government to be given an efficiency rating. The test consists of replacing the anode with a rod that has a series of temperature probes to measure the water at different levels in the water heater. Since water would form l…

Isn't this a symptom of the exact testing procedure being a white box that rarely changes? Many students would score 100% on the ACT if the entire question and answer set were widely published. Also that seems like a silly test. Couldn't you just measure the differential after mixing? TFA also mentions it, but noise is also a factor. For the water-heater example, the limited number of probes introduces a known amount…

This phenomenon also appears in the testing of crash helmets. The DOT (US government) helmet standard is easy to game since it's very strict on how and where the helmets are tested. The Snell Foundation standard is a bit better since the humans testing the helmets are allowed to look for weak points to target for anvil drops. The new FIM standard adds more variability to the tests to better simulate the varying angles of crashes.

https://youtu.be/uLj9WfoWPSQ?t=413

Re: How well do cars do in crash tests they're not optimized for?

#156

Post by ummonk »

Is passenger side small overlap really a common form of collision? I would imagine since everyone drives on the right side of the road, most higher speed small overlap collisions would be on the driver side. Perhaps car manufacturers were right not to optimize for passenger side small overlap collisions?

Frankly though, this is an area where I don’t think it is all that harmful for the metric to become the target, since the metric itself can be modified to reflect common crash conditions, and signal to car manufacturers what kinds of collisions should be optimized for to improve real world safety.

One big feature missing from the current suite of crash testing though is small vehicles colliding with larger vehicles. Walls only simulate colliding with the same vehicle, but small vehicles are especially vulnerable in collisions with larger vehicles.

Re: How well do cars do in crash tests they're not optimized for?

#157

Post by GloriousKoji »

fractionalhare wrote: post #110
YetAnotherMatt wrote: post #83

Earlier quoted context omitted.

For almost everyone 18-40 year old, driving less is one of the healthiest decisions you can make. A little nitpick: Motorcycling, cycling, and walking are all significantly worse than traveling by car. If this interests you, it's possible to find a lot more interesting research by searching for "microlife" and "micromort".

Is that a typo, or do you teally mean cycling and walking are significantly worse than traveling by car? Are both of those activities actually more dangerous? I would have thought cycling and walking - even in urban settings! - are safer activities than driving, statistically.

It's a skew of metrics. Cycling has more fatalities per mile than driving. A higher percentage of cyclists die per year than motorists. In an accident with a car a cyclists has much much higher probability of death than the motorists. But are those really fair comparison?

Re: How well do cars do in crash tests they're not optimized for?

#158

Post by PeterisP »

hangonhn wrote: post #98
YetAnotherMatt wrote: post #83

Earlier quoted context omitted.

For almost everyone 18-40 year old, driving less is one of the healthiest decisions you can make. A little nitpick: Motorcycling, cycling, and walking are all significantly worse than traveling by car. If this interests you, it's possible to find a lot more interesting research by searching for "microlife" and "micromort".

Can you explain more about the walking part? Is it because pedestrians get hit by cars a lot? Otherwise it seems walking should be incredibly safe.

Transportation safety is generally measured on a distance basis. If you compare one hour of driving vs one hour of walking, then walking is safer, but if you compare the traffic risks of driving a hundred miles and walking a hundred miles, then that's a different story.

Re: How well do cars do in crash tests they're not optimized for?

#159

Post by hansvm »

kcolford wrote: post #32
nostrademons wrote: post #29

Earlier quoted context omitted.

An interesting instance of the self-selection problem seems to show up if you select small 4-door 2017 cars. The Nissan Juke 2WD has a death rate of 12; the 4WD version of the same car has a death rate of 65. I have trouble believing that there's a significant difference in the cars themselves, so it seems likely that people who would buy a 2WD small SUV are a significantly different demographic than those who would…

I think it's more relevant how much each group drives. Everyone I know who drives a lot espouses how important 4WD/AWD is, whereas the people who barely drive at all aren't willing to pay so much more for it.

I've always found it a bit amusing how common this belief is, especially in snowier areas. Most people would be safer without 4WD/AWD -- less likely to oversteer around a curve, and less likely to drive aggressively because of a false belief that AWD will help you stop faster or have better control of your vehicle in low-traction conditions.

It's still a really nice feature that has its uses, but most people I talk to about it (admittedly a small subset of people who use AWD) greatly overestimate its safety benefits.

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