3 ms·

When I cross-reference the lane lines at 0:03 with google maps[1], I get an estimate of the car being about 60ft-70ft away from the victim when I was first able

by lhorie 9y ago

When I cross-reference the lane lines at 0:03 with google maps[1], I get an estimate of the car being about 60ft-70ft away from the victim when I was first able to spot her shoe in the video. Some googling[2] says human reaction at 40mph would've taken 59ft, with an additional 80ft of actual stopping time. This seems in line with the police report that "it would have been difficult to avoid this collision in any kind of mode (autonomous or human-driven)" Maybe a SDV with superhuman reaction time should've been able to stop some 10ft after hitting her, and maybe if it had night vision-like sensors, it should've been able to see her from farther away, but my impression is that it would've been impossible for a regular human driver to avoid this accident. Given that the SDV didn't attempt to reduce speed before she was visible under regular light, I'm forced to assume the sensors do require light in order to detect obstacles and that there wasn't enough light to activate the sensor before the headlights illuminated her. [1](https://www.google.com/maps/@33.4369852,-111.9436199,113m/data=!3m1!1e3 https://www.google.com/maps/@33.4369852,-111.9436199,113m/da...) [2]https://www.google.com/search?q=stopping+distance+40mph&rlz=1C5CHFA_enUS746US746&oq=stopping+distance+40mph&aqs=chrome..69i57j0l5.5503j0j7&sourceid=chrome&ie=UTF-8 https://www.google.com/search?q=stopping+distance+40mph&rlz=...

deleted 9y ago
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burger_moon 9y ago
The speed limit is only 35 not 40 on that road unless we're looking at different roads? If the driver is paying attention they could turn the wheel a bit and split the left lane (there doesn't appear to be anyone else on the road) and avoid the person who was half way through the lane at time of impact. Might not clear the person but clipping the back of the bike would certainly be better than a direct impact. You wouldn't even have to jerk the wheel and swerve at such a slow speed and on a dry road with modern tcs even over-correcting is handled by tcs to limit what your input does. Of course all this is just playing arm chair quarterback so who knows if someone including myself would have been able to react in time. More of a thought experiment to how an alternative could have occurred. I'm curious how the visibility differs between what we see on this camera and what a human actually sees in person.
- deleted 9y ago
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- lhorie 9y ago
  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.
jcranmer 9y ago
There are two caveats to interpreting the video: 1. Human eyes have a better dynamic range than cameras do. The camera is thus displaying a worse contrast than a human eye can see. 2. Motion is preattentive in the visual system. (When you think about it, panicking about subtle motion in the corner of your eye tends to be evolutionarily advantageous). So the time we have to identify the pedestrian using the video is a minimum bound of the time, not necessarily an accurate reflection of the time. It is not clear how much extra time (if any) a reasonable driver would have in this incident.
- ThrustVectoring 9y ago
  On a collision course, there's zero relative motion of the object you're about to collide with. It's one of the quirks of the human vision system that makes it particularly ill-suited to operating motor vehicles.

by lhorie 9y ago

deleted 9y ago

[deleted]

burger_moon 9y ago

The speed limit is only 35 not 40 on that road unless we're looking at different roads? If the driver is paying attention they could turn the wheel a bit and split the left lane (there doesn't appear to be anyone else on the road) and avoid the person who was half way through the lane at time of impact. Might not clear the person but clipping the back of the bike would certainly be better than a direct impact. You wouldn't even have to jerk the wheel and swerve at such a slow speed and on a dry road with modern tcs even over-correcting is handled by tcs to limit what your input does. Of course all this is just playing arm chair quarterback so who knows if someone including myself would have been able to react in time. More of a thought experiment to how an alternative could have occurred. I'm curious how the visibility differs between what we see on this camera and what a human actually sees in person.

deleted 9y ago
[deleted]
lhorie 9y ago
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.

jcranmer 9y ago

There are two caveats to interpreting the video: 1. Human eyes have a better dynamic range than cameras do. The camera is thus displaying a worse contrast than a human eye can see. 2. Motion is preattentive in the visual system. (When you think about it, panicking about subtle motion in the corner of your eye tends to be evolutionarily advantageous). So the time we have to identify the pedestrian using the video is a minimum bound of the time, not necessarily an accurate reflection of the time. It is not clear how much extra time (if any) a reasonable driver would have in this incident.

ThrustVectoring 9y ago
On a collision course, there's zero relative motion of the object you're about to collide with. It's one of the quirks of the human vision system that makes it particularly ill-suited to operating motor vehicles.