that is a bold statement to make from the video information we got, at least in my opinion. I would estimate the speed to be at least 50 km/h which gives 25 m as a very rough estimate for the stopping distance without reaction time. It's probably better than that but not 8 m.
But I do agree that the car doesn't seem to have stopped at all and missed the victim completely.
A X,000lb car going 38mph takes a certain amount of time and distance to stop, even with a perfect reaction time. If she really did step out in front of the car with less than that distance to spare, than there wasn’t much to be done, sadly.
The woman cannot go from being "not in path" to "in path" instantaneously unless you believe in teleportation. Supposing the woman got about 1 foot into the path of the car before being struck, the car would have had a minimum of 1 ft / <woman's speed in ft/s> seconds to react, assuming total blindness until the woman was "in path" (I can't think of a real world scenario where this assumption would be strictly true). Suppose a speed of 12 ft/s (~8mph), the car would have had a minimum of 8/100ths of a second to react. Supposing 3 ft of visibility before in path (about the distance from edge of car to lane), the car would have a minimum of ~1/3 second to react. That's assuming the woman was biking along at a good clip already, which is unlikely given that she was crossing a road. So, in all likelihood, the car had over 1/3 of a second to do something. That's just above the typical reaction time of a human (~1/4 second), but I don't think it's an unreasonable expectation for an autonomous vehicle.
Yes, I see. So she walked maybe 2 meters into the lane before being hit. At a slow walk (1 meter/second) that's 2 seconds. At 17 meters/second, that's 34 meters. And it's about twice nominal disengagement time. So yes, it's iffy.
Police concluded that given the same conditions, Herzberg would have been visible to 85% of motorists at a distance of 143 feet (44 m), 5.7 seconds before the car struck Herzberg.
A vehicle traveling 43 mph (69 km/h) can generally stop within 89 feet (27 m) once the brakes are applied.
The police explanation of Herzberg's path meant she had already crossed two lanes of traffic before she was struck by the autonomous vehicle.
I was also misled by the poorly exposed "official" video. Given the numbers above there was time for a human driver to see her and even come to a complete stop. Further since she was moving from one side of the road to the other and only entered directly into the vehicle's path in the last 1.3 seconds (image in "Software issues" section of wikipedia article) it is likely that all that would have been needed to avoid the collision would have been a minor slow down and she would have completed her crossing safely.
> which part of the fatalities happened > 130kmph?
Usually (not always) you realize that something bad is going to happen so you are going to brake. Let's assume there is an obstacle in front of you that is 150m away. After a reaction time of 1 second, and with continuous braking over 100m you are able to get from 180kmh to 100kmh at time of impact, but if you had started from the generally suggested 130kmh, you would have stopped 40m before the target (assuming -8.83m/s^2 braking acceleration).
Whoa hold on, table 1 of stopping distances is calculated for 2.5 second reaction time which is 10x longer than conventional human reaction time. Then the stopping distances are compared to radar/lidar/camera to argue that AVs can struggle to stop within detection range.
It's possible a computer might need 2.5s to make a decision to stop. But the current analysis isn't based on that.
This analysis seems really suspect to me. Any clarification would be appreciated.
> In other words, these drivers did not leave enough distance to react and brake.
Again, recommended following distance is ~250-300 feet when stopping & reaction time can be 350-400 feet. This is OK when the car in front of you brakes, because you'll both be decelerating with a similar profile and you'll have more than 250-300 feet to stop. It is not OK when the car in front of you stops substantially faster than braking with no warning because it has hit an unknown obstacle.
At 45mph the car is traveling at 66 feet per second, so 1 second before impact means it was spotted at approx. distance of 66 feet. The volvo XC90 breaking distance at 62mph is 112 feet. Dividing by the square of the speeds gives us a 45mph stopping distance ~62 feet. So not only would it have saved her life, it could possibly have prevented the car even touching her. (The XC90 has excellent breaking, btw, better than a range rover sport or an audi Q9).
> When the vehicle ahead emergency brakes or stops you have the growth of size of the target to gauge by. That's not much movement, until the last moment when it's far too late to evade.
You see the brake lights up, and as long as you're alert and keep some distance you're going to be alright. If you're not alert and/or driving too close you hit it.
That's a really good point that many (myself included) aren't mentioning. Stopping distance is a universal, reaction times be damned. Would be curious to see if that played a part.
We know the car was going roughly 40mph, so that puts some constraints on the minimum response time that was available. Unless this woman literally catapulted in front of the car, there were at least 4’ of lateral walking pace worth of 40mph time to react. You do need to make assumptions about how fast she was moving, of course, and as has been noted elsewhere in the thread you have to assume that the driver was in the left lane for this scenario to even be remotely plausible. Even in this sequence, the car should have been able to substantially decelerate but, looking at the pictures, that doesn’t seem to have happened.
The detection at 6 seconds was just of an object though, not an object moving in to the car's path. You couldn't drive a car if you had to constantly break because objects (such as people standing by the road) were being detected.
It's not clear at what point the car ascertained a collision would occur between detection 6s before and the determination that emergency breaking was necessary 1.3 seconds before.
Was there any other determination in between, and when? What I'd like to see is Uber's modelling of the woman's trajectory and the likeliness of collision across the 6 second window. That's completely left unsaid.
The average braking distance of a car is about 24m at 40mph, which is approximately the distance between the woman and the car at 1.3 seconds out. So perhaps the 1.3s figure wasn't the first moment the car determined a brake was necessary, but rather, the last moment the car could have braked to prevent a substantial collision. I want to know the first moment the car determined a brake was necessary at all. It's likely not 6s, but it's also likely not 1.3 seconds. It seems this was entirely preventable, or at least the collision impact could have been mitigated severely, had there been a braking and/or warning system in place.
Shutting off brakes on literally the only driving agent tasked with full attention is inexcusable. But that's what they did. To me that's murder. They used to have two passengers, one for tagging circumstantial data, the other to override the car when necessary and keep eyes on the road at all times. Either keep that and shut off emergency brakes from the car and put a warning system in place for the 'driver'. Or do not shut off emergency brakes. Instead they put a single person in the car, tasked to do things that kept her eyes off the road half of the time, and shut off brakes for the AI. That's insane.
But the point is, she was well within the field of detection at that range.
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