[Vik1ng]

Just funny that the 40% from Autosteer seem to exactly match with the general AEB safety improvement rate also mentioned in the report...

    IIHS research shows that AEB systems meeting the commitment would reduce rear-end crashes[emphasis added] by 40 percent. IIHS estimates that by 2025 – the earliest NHTSA believes it could realistically implement a regulatory requirement for AEB – the commitment will prevent 28,000 crashes and 12,000 injuries.

[GrantS]

Here is some of that IIHS research [1] from Jan 2016 that gives lots of raw crash numbers broken down by manufacturer, type of system (AEB/FCW), injuries involved, etc. Really informative.

Some excerpts from "Effectiveness of Forward Collision Warning Systems with and without Autonomous Emergency Braking in Reducing Police-Reported Crash Rates", January 2016:

"FCW alone and FCW with AEB reduced rear-end striking crash involvement rates by 23% and 39%, respectively. "

"Among the 15,802 injury crash involvements in these states, the percentage of injury crash involvements that were rear-end striking crashes was larger among vehicles without front crash prevention (15%) than among vehicles with FCW alone (12%) or FCW with AEB (9%). Only 4% of rear- end injury crashes involved fatalities or serious (A-level) injuries."

"Approximately 700,000 U.S. police-reported rear-end crashes in 2013 and 300,000 injuries in such crashes could have been prevented if all vehicles were equipped with FCW with AEB that performs similarly as it did for study vehicles."

[1] http://orfe.princeton.edu/~alaink/SmartDrivingCars/Papers/II...

[yohui]

For those unaware, "AEB" stands for "Autonomous Emergency Braking". See: https://en.wikipedia.org/wiki/Collision_avoidance_system

Did Tesla cars have AEB prior to Autopilot installation? If not, then this suggests the 40% reduction in crashes may simply be due to the installation of an AEB system. What effect Autopilot's other features may have would remain uncertain.

[greglindahl]

Yes, Tesla cars had AEB since March 2015. Autopilot (with autosteer) came out in October 2015. Presumably Tesla's AEB gets improved a little with every firmware release.

[yohui]

Thanks. But the NHTSA report looks at data starting with "MY 2014" (i.e. calendar year 2013) cars.

If AEB did lead to a 40% reduction in crash rates for Tesla cars, as it did for other car models, I suspect that moving the dividing line by five months later wouldn't change the figures much: you would still have a lot more crashes prior to AEB and fewer after.

[greglindahl]

Tesla was growing rapidly in that era, and the sensors weren't even available at the start of calendar year 2013. All cars shipped with sensors starting in October 2014. It'd be nice if the NHTSA report quantified this a bit, but they didn't. I don't think your suspicion is correct: some of the AEB benefit is in the earlier figure, and the number of airbag deployments is not small.

[yohui]

> Tesla was growing rapidly in that era, and the sensors weren't even available at the start of calendar year 2013. All cars shipped with sensors starting in October 2014.

I don't follow the statement about sensor availability. That doesn't seem to change the fact that all the miles driven "after Autosteer" benefited from AEB, while at most a small fraction of the miles driven "before Autosteer" would have had AEB available.

Given that we know AEB systems do reduce frontal collision rates by 40% for all cars, as the NHTSA report stresses, that implies we cannot attribute the reduction in crashes "after Autosteer" to Autosteer alone.

(Which matters because articles such as the one posted are claiming a cause-and-effect relationship between the introduction of Tesla Autopilot and a reduction in crashes, but if a significant portion or even all of the reduction is due to AEB systems that other cars have also started to adopt then we're mistaking correlation for cause.)

[greglindahl]

I don't believe they counted cars without the sensors, either before or after. Your statement about "at most a small fraction" has no evidence.

Finally, who said the reduction in crashes is Autosteer alone? Not me. It appears to be a combination of AEB and autosteer. That's what "some of the AEB benefit is in the earlier figure" means.

(Edit: note that the above comment was edited without marking the edit. See below.)

[mikeash]

Tesla model years match the year of production. 2014 Teslas were built in 2014.

Tesla rolled out AEB in March 2015 as a software update for all cars with the appropriate hardware. All Teslas produced starting in mid-September 2014 have the appropriate hardware, so several thousand MY 2014 Teslas have AEB as of early 2015.

[celticninja]

I don't think it suggests it as much as it can be inferred from looking at both sets of data.

[mannykannot]

Exactly - this is a significant weakness of the study.

[guelo]

Yea, it really doesn't seem like autosteer would avoid that many crashes. All that autosteer does is keep you in your lane on a marked highway. Human errors that autosteer would correct are probably relatively rare, things like distractedly drifting into another lane or falling asleep at the wheel. AEB, on the other hand, helps avoid the most common type of crash, rear end collisions.

[JoshTriplett]

Autosteer can also change lanes, and would avoid crashes caused by missing a vehicle in a blind spot. Seems particularly useful on a busy highway, with vehicles in adjacent lanes leaving far too little following distance between each other.

[mikeash]

If the car can detect something in the adjacent lane, then it'll give you a warning if you try to change lanes into it manually too.

[bluGill]

My car has that - there are too many false positives for it to be useful. I most commonly hear get the warning when there are two left turn lanes and I'm in the right one (because I need to turn right at the next road). Sure there is a car to my left, if it doesn't turn left I'll hit it, but the other car would be at fault in that case.

I will admit that there have been a couple times it saw the car I was about to merge into before I did. It is not clear if I would have seen the car a moment latter anyway or not.

[mikeash]

Mine has never had a false positive. I've yet to accidentally merge into anybody with it, so I don't know how it behaves in the situation it's supposed to handle.

[jessriedel]

"Number of crashes" is not as important as "crashes weighted by severity". "Distracted driver" is the number 1 root cause of accidents, and "failure to stay in lane" is the number 1 proximate cause of fatal accidents in most states.

http://www.businessinsider.com/the-cause-of-the-most-fatal-c...

[guelo]

OK but the cited 40% figure is just for crash rates, not for severity weighted crash rates.

[__derek__]

A stylistic note: putting quotes in code format like that makes them unreadable on mobile browsers. It's a single-line side-scrolling element with three words in frame at a time that I can only see after lifting my thumb.