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Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

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Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#421

Post by lhorie »

Tepix wrote: post #363
cthalupa wrote: post #344

Earlier quoted context omitted.

>Oh, and they speed. 3mph variance is perfectly normal even on modern cruise control. And even on most modern cards, what you see on the speedometer is often off by ~1 mph at low speeds, and even more at higher speeds. (This is the reason you will often see people talk about 'GPS verified' speeds when it comes to talking about the top speed they have achieved in a car). Federal law in the US only requires they be acc…

3 mph is almost 5km/h. If their technology is unable to stay within 3mph of a certain speed (which is laughable), they should drive 3mph slower than the speed limit.

In Toronto, if a sign says 60 (km/h), the driving instructor will tell you that you're supposed to go at about 65. In Sao Paulo, a 50 sign often means the radar is calibrated to ticket you at 50.1. We can't really make any judgment about being off a few miles unless we know what's the prevailing interpretation of speed signs in Tempe.

Besides, some commenters already pointed out that the google maps of the road in question says that the speed limit is actually 45 northbound (which was the direction the car was going), whereas the 35 number is the speed limit southbound.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#422

Post by Balgair »

sol_remmy wrote: post #415
Cybiote wrote: post #289

Earlier quoted context omitted.

An important observation is that the probability of death drops very rapidly with drops in speed. A rough calculation shows that at 38 mph and a near instant reaction (as a robot should) would within ~1 second of applied breaking force, allow going from a ~70% chance of death to ~5%. A very rough calculation: v(t) = -μgt + v_0. To reach 32 kph or 20 mph, t ~= 0.82/μ, guessing a fair μ=0.8 and the chart here https://e…

Except if the speed limit is 35, you need to drive 35. You can't drive 25 just to be more "defensive", that will get you a ticket.

Typically, no. There are some municipalities and areas of road where there is a minimum speed limit, but in the US, those are very rare. Granted, a law enforcement officer has wide jurisdiction to determine if you are 'safe' to drive and a low speed may become unsafe. But they are unlikely to ticket you and are more likely to try to help you out. Driving under the speed limit may be annoying, but it is nearly-universally not illegal.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#423

Post by Balgair »

Cybiote wrote: post #289
isaachier wrote: post #234

Earlier quoted context omitted.

I think you might be confusing "defensively" with perfectly. There are situations even defensive driving cannot prevent. For example, any car going 35 mph will need a few feet to brake if something jumps directly in front of it. Defensive driving just accounts for one's surroundings and likely outcomes. Seeing as the cars have been on the road in Arizona for a while, and this is the first we are hearing about a pedes…

An important observation is that the probability of death drops very rapidly with drops in speed. A rough calculation shows that at 38 mph and a near instant reaction (as a robot should) would within ~1 second of applied breaking force, allow going from a ~70% chance of death to ~5%. A very rough calculation: v(t) = -μgt + v_0. To reach 32 kph or 20 mph, t ~= 0.82/μ, guessing a fair μ=0.8 and the chart here https://e…

For the people that practice street-math, Kinetic Energy goes as (velocity)^2. So halving the speed reduces the energy to 1/4. A third of the speed is 1/9th the energy. etc.

As you go faster, your energy goes up exponentially. This is why there are bitter fights about increasing the speed limit on roads; they become exponentially less safe (big caveats apply, naturally).

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#424

Post by rripken »

Balgair wrote: post #423
Cybiote wrote: post #289

Earlier quoted context omitted.

An important observation is that the probability of death drops very rapidly with drops in speed. A rough calculation shows that at 38 mph and a near instant reaction (as a robot should) would within ~1 second of applied breaking force, allow going from a ~70% chance of death to ~5%. A very rough calculation: v(t) = -μgt + v_0. To reach 32 kph or 20 mph, t ~= 0.82/μ, guessing a fair μ=0.8 and the chart here https://e…

For the people that practice street-math, Kinetic Energy goes as (velocity)^2. So halving the speed reduces the energy to 1/4. A third of the speed is 1/9th the energy. etc. As you go faster, your energy goes up exponentially. This is why there are bitter fights about increasing the speed limit on roads; they become exponentially less safe (big caveats apply, naturally).

So if you are going 10% faster (38 vs 35) you have 121% the kinetic energy.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#425

Post by lhorie »

cpncrunch wrote: post #419
lhorie wrote: post #414

Earlier quoted context omitted.

You are ranting about reckless speeding, which I agree 100% with you that it's a stupid thing to do. But the comment you replied to was talking about following traffic flow, which is about minimizing speed differentials between vehicles so as to minimize triggering fits of impatience in drivers around you.

My point is that: [1] It's not my problem if others get irate because I'm at the speed limit. [2] It's not dangerous to be at the speed limit, it's dangerous to be over it. And you're not likely to hit someone going at the speed limit if you're dangerously speeding, you're likely to hit the median or an oncoming car, and more likely to get killed doing so (much greater speed differential than between the speeder and…

> It's not my problem if others get irate

It's not like in kindergarten where kids point at each other yelling it was the other who started it. If someone does something dangerous around me, it absolutely concerns my family's safety, regardless of what triggered the dangerous situation. Thinking two steps ahead to prevent these situations from occurring in the first place is at the core of defensive driving philosophy and it's why it's often recommended that one pick going with traffic flow instead of going at the posted speed limit if forced to choose given traffic conditions.

I agree that in many roads, going above the posted limit is a very accurate measure of recklessness, but that isn't the case everywhere and it isn't at all uncommon that the flow of traffic is 10 or even 20 km/h over the posted speed limit on many freeways or countryside roads.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#426

Post by Balgair »

rripken wrote: post #424
Balgair wrote: post #423

Earlier quoted context omitted.

For the people that practice street-math, Kinetic Energy goes as (velocity)^2. So halving the speed reduces the energy to 1/4. A third of the speed is 1/9th the energy. etc. As you go faster, your energy goes up exponentially. This is why there are bitter fights about increasing the speed limit on roads; they become exponentially less safe (big caveats apply, naturally).

So if you are going 10% faster (38 vs 35) you have 121% the kinetic energy.

My math says it's ~1.18 times more KE.

But yes, about 1/5th more KE with just a 3 mph difference.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#427

Post by cpncrunch »

lhorie wrote: post #425
cpncrunch wrote: post #419

Earlier quoted context omitted.

My point is that: [1] It's not my problem if others get irate because I'm at the speed limit. [2] It's not dangerous to be at the speed limit, it's dangerous to be over it. And you're not likely to hit someone going at the speed limit if you're dangerously speeding, you're likely to hit the median or an oncoming car, and more likely to get killed doing so (much greater speed differential than between the speeder and…

> It's not my problem if others get irate It's not like in kindergarten where kids point at each other yelling it was the other who started it. If someone does something dangerous around me, it absolutely concerns my family's safety, regardless of what triggered the dangerous situation. Thinking two steps ahead to prevent these situations from occurring in the first place is at the core of defensive driving philosoph…

I disagree that going at the posted speed limit when someone behind me is going faster is dangerous, or that the person going at the speed limit is at fault. If anyone in this scenario is creating danger it is the person speeding. Generally it is not "everyone" who is speeding, only a percentage. If everyone is going over the limit and it creates a dangerous situation if someone drives at the limit, then there is some serious problem with that road and it needs fixed urgently (either by increasing the limit, or by enforcing the existing limit). It's unhelpful and silly to suggest that people must break the law to be safe, and it completely defeats the point of speed limits and the rule of law, not to mention common sense.

Defensive driving means looking ahead and predicting when someone is going to do something stupid, not braking hard if someone is behind you, being very careful when changing lanes, driving in a parking lot, etc. It definitely doesn't mean driving above the speed limit to keep people behind you happy.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#428

Post by TheCoelacanth »

cthalupa wrote: post #387
Tepix wrote: post #377

Earlier quoted context omitted.

That's a lot of text for explaining why a car might go to 3mph too fast. There is a big difference between a cruise control and an autonomous car. In Germany you can get a ticket for going more than 3km/h (1.875 mph) too fast. It's not acceptable for a self driving car to go so fast that you can get a ticket. If that means going up to 6mph too slow, I guess that's the way it is. Also, going 5km/h means you will need…

It's an explanation of how cruise control works. It sounds like cruise control is dangerous to use in Germany, based on your description. My 2012 VW GLI certainly did not stay within 3km/h of the set speed when utilizing cruise control. >If that means going up to 6mph too slow, I guess that's the way it is. If you want to be in a situation that is more dangerous than going 3mph over the limit, sure. If everyone was g…

> It sounds like cruise control is dangerous to use in Germany, based on your description. My 2012 VW GLI certainly did not stay within 3km/h of the set speed when utilizing cruise control.

You don't need to stay within 3km/h of the speed limit to follow the law. You need to stay below 3km/h over the speed limit. So if your cruise control has a variance of 5km/h, you should set your cruise control at 2km/h below the speed limit.

> If you want to be in a situation that is more dangerous than going 3mph over the limit, sure. If everyone was going 6mph under the limit this would be fine, but staying closer to the speed of traffic around you is less likely to cause accidents than going significantly slower.

Unless your cruise control has a significantly larger variance than all of the other vehicles, you should be fine because everyone else should be setting their cruise control to roughly the same thing as you.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#429

Post by TheCoelacanth »

kwillets wrote: post #411
freyir wrote: post #379

Earlier quoted context omitted.

> any car going 35 mph will need a few feet to brake if something jumps directly in front of it. It seems like you're working pretty hard to justify this woman's death. She was apparently walking her bicycle through an intersection. Did she grab her bike and jump directly in front of the car? Maybe, but let's not jump to assumptions. > it seems the algorithm is pretty safe It ran at least six red lights in San Franci…

I agree but one nitpick: merging into the bike lane before a right turn is the correct maneuver.

At least in some jurisdictions. I remember seeing articles about Uber getting in trouble for doing this in jurisdictions where it is not the correct behavior and for not doing it in jurisdictions where it is the correct behavior.

Re: Police Say Uber Is Likely Not at Fault for Self-Driving Car Fatality in Arizona

#430

Post by TheCoelacanth »

URSpider94 wrote: post #393
chopin wrote: post #381

Earlier quoted context omitted.

As far as I understand your comment, driving at the speed limit is unsafe because everybody is speeding. Sounds like a self-fulfilling thing. Maybe it would be even safer if the majority would obey the speed limit?

Did you read the link I posted? Theres lots of empirical data out there that says that drivers drive the same speed on a road, regardless of the posted limit. That speed is based on their judgment of the road - sight lines, shoulder width, sharpness of curves, etc.

People speed because of poor road design and poor enforcement of speed limits.
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