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.
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.
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.
You're massively underestimating human response time to visual cues and also the distance needed to stop a vehicle traveling at 35-40mph. It takes a full quarter of a second to respond to a visual stimulus on average, and more than that to also move your foot and depress a brake pedal. By that time the car was less than 50 feet from the pedestrian. At 40mph braking distance is about 80 feet in good conditions. There is absolutely no way a human driver could have avoided this accident assuming the same visual distance and dynamic range as the camera. Best case, the car may have slowed down a bit before impact.
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).
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.
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.
>It's likely that the accident still would have been fatal, or at least the pedestrian would have been seriously injured if the safety driver was driving. Based on the video there was only a second or two to react from the time the pedestrian stepped out of the shadows, and human reaction time varies from 0.7 to 3 seconds [1]. One study found the average driver's reaction time is 2.3 seconds.
Yes, but it is difficult to state that it would have been "likely" fatal, and even sevral fractures are IMHO a big improvement over death, the whole point is not about the "average" braking time (BTW that same study gives 1.64 seconds average for "steering away" which is probably what most human drivers would have done in a similar situation, instead of braking or instead of only braking), it is the peaks that count.
I mean, it is about the (rightful) expectation that an automated system is safer (faster, more reactive) than the best you can find (not the average, the best) "in nature" among a random set of drivers, just like the state codes (correctly) take the worse case in the sample or however incereases the recommendation to three seconds.
If you play the game suggested on the same site you gave a link to and deliberately count up to three before clicking, you get:
Reaction time: 2916.00ms
Reaction speed age: 89 years old
Playing fairly, you are likely to get values in the range 300-500 ms.
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.
Human reaction time to unexpected events is at least 400 mS. Autonomous car reaction time can be as low as 40 mS. You can slow down a lot in those 360 mS (about 6 mph) which can turn a fatal accident into a moderate one.
The vast majority of accidents are due to sloppy, aggressive, or distracted driving, which autonomous vehicles will completely eliminate.
exactly this. what's the response time of software? it ought to be close to zero and significantly faster than human's. let's say it's a generous 0.5s - no brakes where applied at all, and even with the crappy darkened video we got (place isn't that dark https://www.youtube.com/watch?v=1XOVxSCG8u0 ) the pedestrian was in view for 2 to 3 seconds.
car didn't see it at all even in those last moments.
I didn't say you can't drive a car without being cautious.
I said you can't drive it without constantly braking the moment you detect an object, irrespective of what the object is doing. (e.g. moving into or away from the driving path).
i.e., just because an object was detected 6 seconds before impact did not mean the car ought to have started braking at that moment. It could be that the object was 200 feet away and moving away from the car's driving path, 6 seconds before impact. It'd be absolutely ridiculous to brake in that situation.
We have no information about this context, e.g. the car's data or determinations within the 6 second window. We only know it detected an object 6 seconds before impact.
It appears like the person I was replying to implied 'the braking distance was 180 feet, but the person was 380 feet away, thus uber could have prevented killing this woman had it not shut off the brakes'. In reality, the 6 second figure isn't relevant. What is relevant is the context that allowed a reasonable driver/AI to determine at a particular point in time, that the car should have slowed/braked. And we don't have that information yet. That's what I'm interested in.
e=mv2, whether or not the driver is a superhuman robot or a human.
This means that there's a fixed distance from which the optimal driver can stop a car doing xmph. Yes, an autonomous vehicle has a faster reaction time* to begin the stop, but no matter the reaction time, a stop cannot be instantaneous from any substantial amount of speed.
If it takes 20 feet to stop a car doing 20MPH, it will take 80 feet to stop a car doing 40mph. If there's a human between the initial brake point and 80 feet from it, that human will be hit, no matter who or what the driver is.
If the driver of car 3 could not see past car 2, and car 2 hadn't realised the Tesla had stopped, and instead swerved out the say 1 second / 90 feet (assume 60mph) before collision, that would give car 2 traveling at a reasonable gap no more than 3 seconds / 270 feet to recognise what was going on and stop.
Should have recognised something odd (a broken down car) within 1.5 seconds, leaving 1.5 seconds to slow down.
Applying brakes from 60mph would mean you'd still be traveling over 40mph when you hit the back of the car.
Thus you need to give more than 2 seconds if you can't see beyond the car in front
Even so, I count a full second from when a human paying attention would have seen something just using this video as eyes, until impact. The stopping distance at 35mph is 136ft, which is 2.65 seconds at 35mph, so the accident would still happen but the impact speed could be lower.
At 40 mph 1.3 seconds is 76 feet, right around the threshold of stopping distance if the computer slammed on the brakes at that moment. At the very least, it's the difference between an ER visit and a fatality. Far too short a time for a human to react to a warning, though.
And at a moderate sprint, like most adults do when they try to cross a roadway with vehicular traffic, that is 4-5 m/s, giving the vehicle 0.4 - 0.5 seconds to stop. 40 MPH ~ 18 m/s that gives the vehicle 7-9 meters to stop.
No human could brake that well, and simply jamming the brakes would engage the ABS leading to a longer stopping distance. Not to mention the human reaction time of 0.5 - 0.75 seconds would have prevented most people from even lifting the foot off the accelerator pedal before the collision, even if they were perfectly focused on driving.
According to google maps, the speed limit is 45 northbound (which is the way the car was going), 35 southbound. The report was that the car was going at 38, but I could not find stopping ranges estimates for that exact number. So give or take a little.
Looking at the video, it seemed like the driver reacted (facially) about a second after she shifted her gaze from some device to the road. It took me several runs of replaying the video to narrow down the time between when I first saw her shoe and collision to about 2 seconds. Also, recall this was at 10pm. In my opinion, swerving or braking with a 1-2 second notice is extremely hard, especially if it's late and you're tired. To be perfectly honest, if it was me, I don't think I would've been able to react at all before the collision.
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.
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.
https://en.wikipedia.org/wiki/Death_of_Elaine_Herzberg
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.
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