If Tesla's autopilot can't detect upcoming stationary objects, it should in the very least keep enough distance between itself and the vehicle ahead in order to allow the human at the wheel to have an unobscured view of the road ahead.
Does Tesla's system have no optical sensors?
Why is it unrealistic, besides the fact that you're following too close behind? If your line-of-sight is shorter than your braking distance, you are driving wrong.
Google shows two-second rule when looking for "safe following distance" - I was taught 3 seconds and it seems more reasonable assuming slightly over a second reaction time.
That changes the story a lot, do you know where you got that information?
It is entirely possible for the vehicle ahead to have an escape path to another lane but you to be pinned in your lane.
Our traffic laws don’t provide for a zero accident environment. They just reduce the damage and suffering to a level society will tolerate.
Suggested by tailgaters?
1) A two-second rule is insufficient.
2) You need more time if you can't see around or through the vehicle ahead of you (and various other reasons, like weather, road conditions, being followed by a tailgater, etc.)
California driver handbook: """ Most rear end collisions are caused by tailgating. To avoid tailgating, use the “3 second rule”: ...
You should allow for 4 or more seconds or when:...
Following large vehicles that block your view ahead. The extra space allows you to see around the vehicle. """
Does this happen frequently enough for you to ignore safety concerns? If so, you should be able to live(or not) with the tradeoff you are making.
Traffic flows best when drivers allow merges, not when they try to close gaps to prevent merges. Most aggressive mergers will quickly merge out as well.
You may even get some "thank you" waves...
Out here in the relaxed midwest most drivers in 60mph traffic seem to follow about 1.5 seconds.
It looks like highway planners expect to get 1900 vehicles per lane per hour at saturation, that averages 1.9 seconds between cars.
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† https://en.wikipedia.org/wiki/Two-second_rule (wherein it proclaims sleep impaired drivers in bad conditions should leave 6 seconds). If you think you need a six second reaction time, pull over and get out of the car.
And in any case, the 2 seconds is not the "suggested follow distance" it's the legal MINIMUM. That is, "You're clearly unsafe if following at any less than this," rather than, "Close up any gaps more than this."
This is different from what happened in the tesla case. What happened here is that the vehicle in front of the car was moving and in view of the tesla's radar sensor obstructing the view of the firetruck. That car then moved and now a stationary object was suddenly in front of the car. From the Tesl's view point, an object just magically appeared somewhere in front of the car.
I'm not familiar with radar systems, but I imagine in this scenario the system isn't precise enough to know that this stationary object that suddenly appeared isn't an overhead sign or some other similar object that pops into the field of view of the radar system. It probably has something to do with radar not being extremely directional, constantly having stationary things pop up due to reflections and various objects in the periphery, having a limited sampling rate, and needing to do a filtering or other sorts of magic to make sure there aren't constant false alarms etc. I can see how cruising along at 50mph, the system doesn't have enough time to figure all this out and stop (e.g. not enough samples or there being a noise floor on stationary object data). It appears the correct way to solve this is with 3d lidar systems combined with sort of of mapping technology, but those are still too expensive/difficult to put into every day vehicles.
I'd had my Subaru slow due to a vehicle bumper sitting in the lane (from a crash that happened shortly before).
>Radar knows the speed of any object it sees, and is also simple, cheap, robust, and easy to build into a front bumper. But it also detects lots of things a car rolling down the highway needn't worry about, like overhead highway signs, loose hubcaps, or speed limit signs. So engineers make a choice, telling the car to ignore these things and keep its eyes on the other cars on the road: They program the system to focus on the stuff that's moving.
https://www.youtube.com/watch?v=FadR7ETT_1k
I guess this was in ideal conditions or maybe the Tesla in the firetruck accident doesn't have this software update.
1. Autopilot didn't leave a big enough gap in front of the Tesla. Presumably because the radar has limited range, or maybe it was a big enough gap but the guy just wasn't paying enough attention.
2. Autopilot ignores stationary objects. This is a deliberate decision - apparently if you don't ignore stationary objects there are too many false positives from stationary objects you aren't driving into (signs, bridges, etc).
The root cause of 2. is that the radar doesn't have good enough angular resolution to say whether something is in your path or not - it can just detect things vaguely in front of you. The solution is probably LIDAR (which everyone except Tesla uses) or maybe some camera-radar data fusion, but obviously it doesn't do that at the moment.
Not being able to tell if a stationary object is something you're going to hit or not (like LiDAR or stereo cameras might do) is more relevant to this case than maps.
Basically, I rear ended somebody - but the details of why that happened are interesting to me.
I was going down a road I usually travelled to go to work that morning; two lanes each direction with a middle "suicide" lane.
Traffic was fairly heavy, as it always is in the area during morning traffic; there's a school not too far ahead in the direction I was travelling, and traffic "bunches up" and slows in the area, thanks to a crosswalk, people dropping kids off, and a "radar speed limit sign" that tells drivers how fast they are going in relation to the speed limit when school is in session (causes people to hit their brakes). Furthermore, not too far after the school is a stoplight for an intersection with another similar road.
Where I was at just before the accident was crossing a neighborhood street at a controlled intersection; also at that intersection, the suicide lane changes to an unprotected left turn lane.
So there I am, tooling along at my normal 40-45 mph (appropriate speed for the street I was on). Coming up on the intersection, a tractor-trailer semi was in front of me; the driver decided to make a left hand turn at the intersection, and got into the suicide-turning-into-a-left-turn lane. I decided to accelerate a bit to go around him. Now - I was kinda in an "autopilot" mode, not paying as much attention as I should have.
The traffic in front of me - thanks to the conditions I mentioned - which were typical of the morning time period, should have clued me in to "slow down" (which I have since taken to heart). That area, due to the traffic and conditions - is a "stop and go" situational nightmare. Traffic moves a bit, slows, maybe stops, starts again - and people do the typical: They don't keep their foot on the brake, so while they are "going slow" or even "stopped" (idling, not enough power to move) - their brake lights aren't "on".
So there I am - going around the truck - and "traffic ahead of me" registers, but I didn't see any brake lights, so while in my "autopilot" morning haste/haze/whathaveyou, I made the incorrect assumption that traffic ahead of me was moving; accelerating, maybe not going as fast as I was, but getting there. Which was the wrong assumption, of course.
The next thing I knew, I recall that the car in my lane ahead of me didn't have his brakes applied enough to turn his brake lights on, but wasn't moving anywhere near my speed; then he hit his brakes full (causing his lights to go on), and I slammed on my brakes just a bit too late in my realization. My speed dropped instantly, but not quick enough - I was probably going 15 mph or so when I rear ended him.
I was driving my 1996 C1500 pickup, his was a small crossover-like vehicle. Not much damage on my end; his bumper was mashed, lights broken, etc. We pulled over, exchanged insurance info, no cops involved, and went on our way. I called my insurance immediately, of course, and let them know what happened.
So it was a combo of things; my "autopilot" inattention, my speed, the traffic situation, the way people were "braking", going around a semi truck that was blocking my view then "road clear" ahead - it all came together in a "perfect storm", ending up with me rear-ending someone.
I tend to think that an autonomous car, or one with automatic braking (features not to be found on my truck at the time), would have been paying "more attention" and would have seen the car ahead of me not moving as fast (never mind the lack of brake lights), and would have hit the brakes and came to a stop much sooner. Indeed, had I been paying better attention, and going a bit slower (perhaps only going 30 or 35 mph), I could have applied my brakes much sooner, and avoided the accident.
Lesson learned, I guess.