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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?

#321

Post by gsnedders »

dionidium wrote: post #305
dmurray wrote: post #301

Earlier quoted context omitted.

Is this still true for commercial flights? The most prominent airliner losses from the last 20 years were not close to takeoff nor to (scheduled) landing. I'm thinking of Air France off Brazil, the two Malaysian planes, all four 9/11 attacks, and the Germanwings crash. The exception is the Concorde crash on takeoff which just sneaks into the last 20 years (July 2000). Of course, part of the reason these crashes were…

My information may very well be out of date! This is one of those lines I've been repeating for 20 years and it might be time to update it.

On a per journey basis, in Europe/US/Canada, considering _only_ commercial aviation (i.e., excluding general aviation), the fatality/journey rate is comparable to both cars and walking.

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

#322

Post by jodrellblank »

sjwright wrote: post #55
octagonal wrote: post #14

Earlier quoted context omitted.

The only safe way to drive an F1 car is with remote control.

No, you could also safely drive an F1 car from the driver’s seat by limiting your speed to 40 km/h.

Could you? Here[1] is Richard Hammond driving an F1 car on Top Gear, and he says it can't go slowly, safely - no downforce, no heat in the tyres, no heat in the brakes. If you're coming off a lot of fast laps into the pit lane they will still be warm, if you try to drive it at 40km/h all the way they won't be.

[1] https://www.youtube.com/watch?v=EGUZJVY-sHo

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

#323

Post by Marsymars »

AgloeDreams wrote: post #260
Marsymars wrote: post #256

Earlier quoted context omitted.

> Oh and SUVs are markedly LESS safe. They are more prone to rollover, less likely to avoid an accident, stop slower, and generally have less safe body structure. But they're also heavier, and there exist cheap, heavy SUVs, while cheap cars are generally lighter.

Weight increases mortality in all accidents. Either by increasing the likelihood of the other driver being injured or by increasing the amount of force impacted on crumple-zones in single car accidents. All modern safety studies have shown this and only recently has any SUV gotten a pure 5 star award. SUVs are less safe than equally priced cars. Also most SUvs cost much more than cars with similar wheelbases.

Yes, but empirically, lots of people don't care about increasing the likelyhood of the other driver being injured.

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

#324

Post by titzer »

esrauch wrote: post #316
nwallin wrote: post #278

Earlier quoted context omitted.

The differences are not pedantic at all. The differences are extremely significant. The VW engineers designed the car to do different thing while being tested vs used by consumers. While being tested, the emissions system was on. While being used by consumers, the emission system was entirely disabled . The water heater engineers designed the water heater to do the same thing while being tested vs used by consumers.…

> If the water heater engineers designed the water heater to never turn on and keep the water at room temperature while being tested I think the difference between what they did and this is only a difference in degree and not kind though, right?

It is a difference in kind: VW dynamically detected and adapted behavior to the test. It would never operate in that way under normal conditions. The water heater example was completely static: it always behaved the same way, under test or not.

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

#325

Post by w-ll »

hinkley wrote: post #194

One of the more morbid yet profound aphorisms that I know is: Safety regulations are written in blood. FAA regulations are often based on finding a new way to break an airplane that they hadn't diagnosed before. Safety ratchets up as new failure modes are discovered. If cars keep showing up pancaked it a particular way, then guidelines change. Until those failure modes are regulatory capture, at least. In the 90's th…

The "pancaking" is designed, modern cars are made to "crush" and absorb the energy of an impact.

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

#326

Post by laegooose »

laegooose wrote: post #5

The whole car safety topic is very confusing. Car accidents is top1-top2 death reason in US for people in 20-40 age group [1]. Probably less in Europe but still one of the leading ones. I was thinking about how I can make myself safer. Which car brand/model is better? Which seat is better for passenger? How much riskier it is to drive during the night? In the rain? How dangerous is it to overtake on road with 1 lane…

[1] https://usafacts.org/articles/americans-causes-of-death-by-a...

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

#327

Post by Spooky23 »

ebg13 wrote: post #134
henryfjordan wrote: post #121

Earlier quoted context omitted.

Imagine the water heater company didn't know they were gaming the test. They first design a water heater and it gets a B- on the test. Being overachievers, they work hard and submit a second design that gets an A+. They might not realize that both heaters are basically the same with the only difference being some heating element spacing that works better for the test. Both times they submitted a legit design that was…

> Imagine the water heater company didn't know they were gaming the test. We don't have to. In this case we have clear admission of intent. The intent to deceive is what makes it fraud and not just being wrong.

There is no deception and no ethical issue. The nature of the test is known.

What placement of components would be ethical? Should engineers required to be separated from the test parameters by a Chinese wall? Do they need to build the system for the worst result? Some middle ground? If the engineers are unethical, where is the line?

The obvious answer to optimizations like this are for the testing body to tweak the test procedure based on what manufacturers do over time. That provides an incentive to be more conservative or accurate.

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

#328

Post by jacquesm »

nimih wrote: post #234
jacquesm wrote: post #149

Earlier quoted context omitted.

I knew a lot more people that died cycling than I knew people that died in car accidents. And all of the cyclists got hit by vehicles.

I'm in the opposite situation, personally. Irregardless, the point I meant to convey is that I'm able to talk myself into both the original claim and its converse, so it's probably better to actually point to a statistical study than try to provide a causal explanation, no matter how compelling.

I think it very much depends on where you live. Here cycling is super popular and so you can expect more deaths even if the deaths per distance number is likely quite low even when compared to places where cycling is less popular due to infrastructure differences.

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

#329

Post by Gibbon1 »

dmurray wrote: post #300
jodrellblank wrote: post #284

Earlier quoted context omitted.

> " water at the level of the heating elements gets hotter and hotter and the water away from it gets cold. " Eh? How come that temperature differential doesn't cause convection? The colder water being more dense and sinking down, the warmer water being less dense and rising up. If the heating elements aren't at the bottom, specifically for this reason, how come they aren't?

> If the heating elements aren't at the bottom, specifically for this reason, how come they aren't? There are typically two heating elements, one near the bottom and one further up. You can use the higher one if you only need a half-tank of hot water. I'm not sure if this is the complete answer to your other question, or if sometimes conditions are such that convection occurs extremely slowly despite a substantial te…

I think perversely it's not the density profile in the vertical dimension that drives convection but the horizontal dimension. A hotter thus lower density but perfectly flat homogeneous layer can't displace the colder denser layer above it because the pressure between the two layers is uniform.

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

#330

Post by nsgi »

dionidium wrote: post #282
PeterisP wrote: post #158

Earlier quoted context omitted.

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.

This is also why the safety of commercial air travel is (sometimes) overstated. Since most crashes happen on takeoff or landing, the risk profile of a 100-mile flight is about the same as for a 1000-mile flight, but on a per-mile basis the latter flight appears safer.

Also because when people are contemplating whether to fly the alternative often isn't using another form of transportation but not travelling at all and using video conferencing, or travelling a shorter distance (e.g. going on holiday more locally)
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