The company revealed the figures in a filing with California’s Department of Motor Vehicles, after the regulator required all autonomous vehicle testers to report incidents.
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The report indicates that a true self-driving auto that can cope with all driving scenarios is still some way off. Google points out though that incidents where the driver takes manual control like the ones mentioned in its report are necessary to ensure all possible scenarios are encountered for in their research. The results probably won’t do much to assuage the fears of those who are unsure about the safety of autonomous vehicles.
According to the report by Google, the cars can also determine the severity of the rain, and just like human drivers they drive more cautiously in wet conditions when roads are slippery and visibility is poor.
Nissan drivers intervened 106 times in 1,485 miles, to avoid being rear-ended after the vehicle braked too fast or crashing after braking too slowly. Tesla had zero disengagements while Google, which has many more test vehicles, had 341.
It’s important to note that conclusions shouldn’t be drawn about the reliability of each company’s vehicles by the stats above. Majority of the mileage were of the cars autonomously driving around the suburbs as well as near and around Google Headquarters in Mountain View, California.
“Our objective is not to minimize disengagements”, Google’s report states.
Google’s fleet of self-driving cars consists of 53 vehicles, the largest fleet of autonomous cars in the country.
The reports can also be a little misleading in the automaker’s favor.
In terms of these experiments, “disengagements” are defined as deactivation of the autonomous technology “when a failure of the autonomous technology is detected”, or “when the safe operation of the vehicle requires that the autonomous vehicle test driver disengage the autonomous mode and take immediate manual control of the vehicle”.
However, Google says that its drivers actually took over the cars of their own accord “many thousands of times”, yet the company is not including those times in its numbers.
In its testing report, then, Google said, “Safety is our highest priority”.
Between the seven companies that filed, there were 2894 disengagements logged.
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Disengagements are a critical part of the testing process that allows our engineers to expand the software’s capabilities and identify areas of improvement. Therefore, we set disengagement thresholds conservatively, and each is carefully recorded.
