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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?

#61

Post by komali2 »

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…

Riding motorcycles means I'm often playing the percentages game. When we turn we're sacrificing our finite amount of traction for either more speed or a more aggressive turn. If I lean off the bike, I get some traction back. So how much am I willing to sacrifice in the name of fun, while still leaving wiggle room for suddenly encountering a tar snake or something in the middle of my turn?

Little things. Motorcyclists in white helmets get hit slightly less, so I wear a white helmet. 50% of Motorcycle fatalities involved dwi level BACs, so I obviously don't drink, but then another 40%ish of the remainder involve any amount of alcohol at all, so I simply don't get on the bike if I've even one drink in the past several hours.

Rain adds risk, night adds risk. Choose one and I'll ride. Both, no.

Majority of accidents happen at intersections, so every single green light has me slowing to look both ways. I watch behind me at reds. I don't get in the middle of intersections to make a left turn, I wait in the turning lane.

The first person I bought a bike from gave me fantastic advice: if you have to think about it for a second, just don't do it. Thinking about that narrow pass on the freeway? Let it go, you can pass in a couple seconds after the gap widens. Thinking about gunning through the yellow? Relax. Just stop. Etc.

I can't speak for cars but so many things are measured for motorcycles. Where our heads hit the ground, what our gear does for us, where we crash. There's also tons of videos from GoPro mounts of many kinds of crashes we get into. Over time you can build a sort of risk management software inside your brain I think.

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

#62

Post by kevin_thibedeau »

dangus wrote: post #21
blakesterz wrote: post #6

Earlier quoted context omitted.

I just took a quick look at Consumer Reports for Vovlo's reliability and they're not great. A couple were even bad. If my memory is right, this has been the case for a while. It looks like maybe Volvos are safe, but not super reliable I guess?

On the other hand, all car makes have become much more reliable than they were in the past. Mostly, what you're looking out for is cost of parts and difficulty of labor. For example, a lot of Audi/Volkswagen products suffer from simple repairs being made more complicated by the need to pull things apart for the mechanic to reach them.

Look at the replacement costs of the mirrors. Anything over $300 is excessive.

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

#63

Post by sjwright »

andrewzah wrote: post #8
amelius wrote: post #7

How about F1 cars?

Has there ever been a full or partial head-on collision with an f1 car?

Colliding with a rigid stationary object is generally just as bad as a head on collision with a similar vehicle. The shortest short hand for why this is so is because each car brings its own momentum and it’s own crumple zone.

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

#64

Post by m12k »

In my university physics course, we did a project where we made our own physics models of car crashes and compared with crash tests and statistical data about real-life crashes. Our conclusion at the time was that crash test results matched our models of collisions with identical vehicles of opposite velocity (i.e. a head-on collision - the most complex case we could solve analytically), which, if you work it out, should come out the same as the normal force when hitting something stationary like a concrete pillar. In this case crumple zones are the most important factor, as they allow you to decelerate over a longer distance. The real life data crash reports though matched the result we got from simulations (which is what we resorted to when the models got to complex to solve analytically), in which case by far the most important factor was the weight of the cars involved in a given crash. Whoever is in the heaviest car will tend to win the game of conservation of momentum. Kind of a sobering conclusion tbh.

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

#65

Post by gok »

One thing I appreciate in supervised machine learning is that it's widely acknowledged that one should not test on training/tuning data. For both computer benchmarks and car crash tests, this is not the case. Both fields routinely work to optimize for a test, which leads to dramatic overfitting. This would be like passing out a standardized test years before students take it.

This seems solvable. For benchmarks, there should be held out tests that don't get distributed to (say) compiler authors until after the results are published. For crash tests, parameters like overlap and speed should be randomized each year so that manufacturers are forced to optimize for a range of possible crash scenarios.

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

#66

Post by spott »

strict9 wrote: post #58

Whenever metrics are instrumented that measure productivity, safety, quality, or efficiency, the metrics and metrics alone are what matter, not the over arching goal. Whether it's car crashes, fuel efficiency, lines of code, completed tickets, OKRs, or anything else, players in the system adjust to optimize output for the evaluated metric. A tale as old as time.

Unfortunately, there isn't really a solution to this problem. Metrics are the only way to measure some things reliably and consistently across users, testers and subjects.

The goal is to have performance on the metric be as close as possible to the desired characteristic. This isn't always possible (and gets really hard when people are involved), but there isn't really any other solution.

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

#67

Post by komali2 »

JoeAltmaier wrote: post #17
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…

Drive the largest vehicle you can. When in a collision the momentum is converted to crushing force, you want to be in the less-crushable vehicle. Hey this may be an unpopular choice, but it is the one with the biggest safety impact! And that was the question.

My buddies and I all subscribed to this theory as young kids in Texas, then one time some of us did a trip to the junkyard to get some parts and it was a graveyard of absolutely demolished pickup trucks. Shook us pretty good. The junkyard guy knew what happened to some of them, too, like this one where the passenger compartment was just a block of near solid steel apparently got in a crash with a Camry.

So I'm not sure "big car safe" is necessarily true.

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

#68

Post by itpwang »

Merrill wrote: post #53

>For a long time, adult NHSTA and IIHS tests used a 1970s 50%-ile male dummy, which is 5'9" and 171lbs. ... >For reference, in 2019, the average weight of a U.S. adult male was 198 lbs and the average weight of a U.S. adult female was 171 lbs. So the average mass of the American male has increased 15% in 50 years! No data on whether he is taller, but I'd bet the BMI has gone up.

Referencing the same line, I remember seeing another article on HN somewhat recently about the downside to taking averages of a human to fit specs since the "average"(mathematical mean of measurements) human never existed in reality. Something about fitting pilots to a cockpit?

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

#69

Post by bluGill »

dangus wrote: post #27
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…

The way to make yourself safer is to move to one of the few American cities and towns with walking and transit-oriented development. Seriously! You'll spend a fewer hours in the car risking car accident death. A family can easily downsize to one car or less. You'll also spend more time getting light exercise by walking to the bus/train, walking to the store, walking for enjoyment. You'll also save from no longer buyi…

Easy to say. I live a long walk from work (normally I ride the bus), now they are talking about moving to a different building that isn't served by transit (20 minute walk to the nearest bus stop), since it isn't that far by car they aren't even thinking about offering relocation expenses so it would cost me more than a new car to move (after realtor fees and other moving expenses). There is no reason to believe that this is the last time they move us.

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

#70

Post by komali2 »

globular-toast wrote: post #45
ambicapter wrote: post #40

Earlier quoted context omitted.

> A 2700lb subcompact vehicle that scores Good may fare worse than a 5000lb SUV that scores Acceptable. This is because the small overlap tests involve driving the vehicle into a fixed obstacle, as opposed to a reference vehicle or vehicle-like obstacle of a specific weight. This is, in some sense, equivalent to crashing the vehicle into a vehicle of the same weight, so it's as if the 2700lb subcompact was tested by…

No.. that still shows it's the truth.

This isn't correcting for whether people can safely drive the biggest vehicles on the road, semi trucks.
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