Tesla safety report and the need for caution - July 2019 update
The latest figures are in the accident rate for cars with Autopilot have improved from 1 accident in 2.91 million miles to 1 in 3.27 million, a 12% improvement over 6 months and reversing the worsening of the accident rates we saw 3 months ago. This is probably statistical noise were the number of actual accidents is relatively low, coupled with some seasonal variation as the northern hemisphere, a region where Tesla are most popular, have been in spring for the last quarter and consequently less ice, less darkness, generally better weather. There's some conflicting reports however that says August is the worst month, we may seem an increase next quarter.
The surprising and most marked improvement is the passive safety results, an increase from 1.58M to 1.76M to 2.19M miles - a 30% improvement.
At the risk of giving the impression Tesla can't win, the improvements in passive safety have massively outperformed autopilot in use, and the ratio now suggests AP is 49% safer than passive safety measures, against the near 100% better performance it was 6 months ago. Both are safer, but the relative improvement of AP, especially when we look at the arguments in the original argument that highlight AP is only used on significantly safer road type and should be up to 4x safer, suggests there is still a long way to go and the advantage and relative safety of AP is falling behind. We'd need more data to be understand the relative numbers for different road types.
We'll rephrase the point. If you are thinking the use of AP is a safety benefit, we don't believe any of the numbers presented by Tesla prove it is, and if anything, the use of AP is now worse relative to simply relying on the passive safety systems.
Our original article
Teslas Vehicle Safety Report stated some interesting, and we use the word lightly, facts.
- "One accident for every 2.91 million miles driven in which drivers had Autopilot engaged."
- "For those driving without Autopilot, we registered one accident for every 1.58 million miles driven."
Lets break this down a bit.
- We have no deliniation between versions of Autopilot. Early cars up until late 2016 had the Mobileye system. It would be interesting to compoare and contrast the superiority (or not) of the Tesla developed system v the long established Mobileye system.
- Autopilot is used predominantly on Motorways/Freeways as this is the road type they were initially limited to and the most common location for use.
UK figures from 2017 state that there were 99 fatalities in 69 Billion miles on motorways v 1068 in 145 Billion rural roads and 626 in 117 Billion urban miles. The data also shows the number of causalities is also roughly in proportion to the number of fatalities. The data therefore suggests the relative fatality (which can be extrapolated for injuries) are 1 in 696M,135M and 186M miles driven on Motorway, Rural and Urban roads or motorways are approx 4x safer than other road types.
A reference to the above data can be found in this UK Goverment report.
- While casualty figures do not directly extrapolate to the number of accidents as one, not all accidents have a casualty and two, a single accident can have more than one casualty, due to the higher typical speeds involved in motorway/freeway accidents it would be reasonable to assume the likelihood of a casualty from a motorway accident is if anything higher than the other road types. This suggests that while motorways are 4x less likely to have a casualty per mile than other road types, the likelihood of an accident of any type per mile even less likely on motorways.
- Autopilot is intended for use on Motorways/Freeways. The capabilities have increasingly become available on other road types and while dismissing any inclusion is not ideal, it is believed the vast majority of autopilot miles will be driven on Motorways/freeways.
We can add in some additional data points. Teslas are expensive cars and its also not unreasonable to assume that the demographic of the typical driver is someone in their 30s and above. These are by far the safest class of drivers per mile with accident rates up to 4x safer than the worst age demographic according to AAAFoundation.
There's also an article on general safety features available on modern cars, some of these features only becoming more common place in recent years such as lane assist and so rare on many older cars. We saw material safety improvements when seatbelts became standard and general reduction in accident rates due to ABS and stability aids, we're now seeing a similar increase from these new features. Forbes top 7 car safety features goes into a little more detail.
Technology improving safety is far from new, the insurance industry for highway safety found a 40% reduction in single vehicle accident rates from the introduction of stability control, technology which some cars still don't have and are part of the baseline statistics, although admittedly the number without is increasingly small.
But lets conclude positivelyWe do not fully subscribe to any argument on the relative safety of Tesla and Autopilot as the data available is far to weak and any number of assumptions can be made. Through the addition of a small amount of additional data to add context, the picture becomes very different and the argument can be skewed to any political agenda you wish to portray.
It would be beneficial if Tesla put more information out there and allowed some impartial and detailed analysis. They should be mindful that when putting out incomplete data sets that give a superficial view on safety it can do more hard than good and potentially give a false sense of security. We have seen too many instances of people abusing Autopilot, and in a number of occasions with fatal consequences. The suggestion that Autopilot is twice as safe as without must not be taken as an excuse to rely on Autopilot.
But lets take the positives, firstly Tesla are one of the first companies to publish any data like this that we are aware of, that's to be commended. Secondly, the cars appear to be able to cover many more miles between accidents than the average, whether it's the passive safety systems that are also on other similar priced and aged cars or driver demographic we don't know, but if you're in a Tesla, you're safer than average. And thirdly, Tesla like several other car manufacturers, are continuing to innovate and push the bar higher, and while we could be sceptical on the current metrics, merits and safety of the systems, innovation and change is how improvements will come about. For that we should all be grateful. Just don't abuse it.