How well do cars do in crash tests they're not optimized for? • Hacker News Board

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

#181

Post by Bartweiss » Tue, Jun 30, 2020, 6:42 PM UTC

dharmab wrote: post #155

ryanianian wrote: post #52

Earlier quoted context omitted.

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 angle…

Crash test dummies have basically this problem also. They're designed for realism in certain very narrow ways, and then the very small number of approved dummies are used for testing car safety.

The industry has made a bit of progress, surprisingly unprompted by regulations - female and child dummies came into circulation before they were required in tests. But overall, testing is still run against a tiny handful of body types which move 'realistically' in only a few regulation-guided respects.

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

#182

Post by csours » Tue, Jun 30, 2020, 6:48 PM UTC

x87678r wrote: post #37

There must be stats for injuries or deaths by car. Is it public?

Must there be? One would imagine that there should be, but comparing over time and from different jurisdictions is quite difficult. What is the baseline? Many car accidents never get reported to any official body (single car accidents, fender benders). How do you classify an injury? I was involved in an incident that looked quite horrifying if you looked at the cars, but no injuries were reported at the time.

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

#183

Post by tpmx » Tue, Jun 30, 2020, 6:52 PM UTC

globular-toast wrote: post #161

jbay808 wrote: post #77

Earlier quoted context omitted.

It's the "let's defect in a prisoner's dilemma" strategy that works great until others use it too.

It is not the prisoner's dilemma at all. If everyone gets big cars then everyone is equally as safe. They don't all die. For crying out loud, people, I know it's stupid, I know it's wrong, but it's the truth. It's an uncomfortable truth that your downvoting will not change.

I think you're on to something.

First: there's vehicle-to-barrier crashes (think trees, etc):

Having a vehicle with a large well-designed crumple zone seems obviously good from a survivability POV.

Second: there's vehicle-to-vehicle crashes:

Is it really a zero-sum game? If a small car crashes head on with a large car, will the people in the small car suffer worse than if they crashed into another small car? To what degree?

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

#184

Post by sokoloff » Tue, Jun 30, 2020, 7:00 PM UTC

hansvm wrote: post #159

kcolford wrote: post #32

Earlier quoted context omitted.

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 t…

The likelihood to oversteer depends on whether the 2WD alternative is front or rear wheel drive. RWD is more likely to oversteer on acceleration in slippery, turning conditions.

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

#185

Post by throwaway0a5e » Tue, Jun 30, 2020, 7:01 PM UTC

BurningFrog wrote: post #174

andykellr wrote: post #26

Earlier quoted context omitted.

This reminds me of the fact that my grandmother who recently passed away at 96 refused to make left turns. She stopped driving years ago, but before she did, my father would always help her find a way to get to the pharmacy, the grocery store, church, and family and friends houses making only right turns. Sometimes she went miles out of her way.

Transgender icon J Edgar Hoover did the same. If it was for safety or because he hated lefties is not clear. https://www.nytimes.com/1975/05/27/archives/exagent-says-hoo...

>Transgender icon J Edgar Hoover

Citation please. This is the first time I've ever heard him called that. There was some speculation he was gay but nothing conclusive AFAIK. In any case he's one of the last people anyone should pick as a positive representation of their group.

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

#186

Post by zip1234 » Tue, Jun 30, 2020, 7:01 PM UTC

YetAnotherMatt wrote: post #83

dublinben wrote: post #12

Earlier quoted context omitted.

You're right that there aren't meaningfully significant differences between car brands. Driving itself is just very dangerous. Other forms of transportation like buses, trains, and airplanes are orders of magnitude safer.[0] If you want to make yourself safer, avoid driving as much as possible. [0] https://injuryfacts.nsc.org/home-and-community/safety-topics...

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".

   Motorcycling, cycling, and walking are all significantly worse than traveling by car.

Is this because of the chance of getting hit by a car?

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

#187

Post by JoeAltmaier » Tue, Jun 30, 2020, 7:02 PM UTC

tpmx wrote: post #183

globular-toast wrote: post #161

Earlier quoted context omitted.

It is not the prisoner's dilemma at all. If everyone gets big cars then everyone is equally as safe. They don't all die. For crying out loud, people, I know it's stupid, I know it's wrong, but it's the truth. It's an uncomfortable truth that your downvoting will not change.

I think you're on to something. First: there's vehicle-to-barrier crashes (think trees, etc): Having a vehicle with a large well-designed crumple zone seems obviously good from a survivability POV. Second: there's vehicle-to-vehicle crashes: Is it really a zero-sum game? If a small car crashes head on with a large car, will the people in the small car suffer worse than if they crashed into another small car? To what…

To an amazing degree. In the limit, the large vehicle proceeds nearly unimpeded and the small one is a ball of tinfoil.

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

#188

Post by spott » Tue, Jun 30, 2020, 7:03 PM UTC

nitrogen wrote: post #125

spott wrote: post #66

Earlier quoted context omitted.

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.

Hidden metrics help, but it is pretty frustrating as an individual to be evaluated based on hidden criteria.

Yea, and no metric stays hidden forever if there is enough money in it getting unhidden.

Statistical metrics have some of the benefits of hidden metrics while staying "hidden" forever, but they also can be much more time consuming to do right and are even more frustrating to be evaluated by.

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

#189

Post by Bartweiss » Tue, Jun 30, 2020, 7:06 PM UTC

ebg13 wrote: post #99

ivanbakel wrote: post #93

Earlier quoted context omitted.

What was more heinous about the VW case IIRC is that the cleanliness gains the cars made on the treadmill setup were enough to push them into compliance with regulations, which the engines normally didn't meet. "Cheating" a better efficiency rating is significantly less reprehensible than cheating a legal obligation which was legislated for public health and environmental reasons.

But the efficiency ratings also exist for public health and environmental reasons. Why does it matter to you that one is a mandate? They're both intentionally deceiving regulators and consumers (vs accidentally acing the test without cheating). Both are fraud.

I do think that manipulating a purely instructive measure is less extreme than manipulating a compliance test; consumers can seek alternate tests and reviews, but the state emissions test has special status even if a dozen other tests give a different result. That said, I believe Energy Star ratings affect tax rebates and electric bills, and they're required to be printed on products - so that's not really an arbitrary test.

There are other differences here too, I think. The water heater trick is passive manipulation that stays in place at all times, which limits how far from "real" performance it can get. And per the story, it seems more like "teaching to the test" than "cheating". That is, Volkswagen consciously moved away from the mandate outside of testing. The water heater was (potentially) as energy-efficient as they could design, with the test score manipulated on top of that.

None of that makes it harmless - if "as good as you can make" doesn't hit standards without manipulating them, that's still a problem. But I do find it less galling than "intentionally worsens emissions outside the test bench".

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

#190

Post by zip1234 » Tue, Jun 30, 2020, 7:07 PM UTC

bcrosby95 wrote: post #25

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…

Driving is already incredibly safe. Yes, it's the leading cause of death in those age categories, but there are 3-4 trillion miles driven each year in the USA. That comes out to 1 death every 100 million miles.

It might be safe personally, but not necessarily for others. I'm guessing the death statistics don't count the deaths caused by cars such as running into pedestrians or cyclists or air pollution deaths as driving deaths?