How safe do self-driving cars have to be before they become road worthy?
No technology is perfect all the time
There's no debate that self-driving cars are coming. But autonomous vehicles won't appear on our roads until regulators have come up with a way to legally permit them to do so - and that's proving very tricky indeed.
Human mistakes are responsible for 94% of the 33,000 deaths on US roads every year. While traffic accidents have declined over the last decade, it's thought that autonomous vehicles - which don't get drunk, tired or distracted - could save more than 30,000 of those.
Yet problems still crop up, as evidenced by the recent prang between one of Google's self-driving cars and a bus. No-one was hurt, but it was the first time that Google's algorithm had been at fault in a crash. Since then, Google has updated its software.
Still Afraid
While it's unarguable that self-driving cars are safer when you look at the statistics, what's difficult is persuading the public that that's the case. Recent polls conducted in several countries show that a majority of people are still afraid of riding in autonomous vehicles.
As such, the burden of proof is on manufacturers - as noted by Adam Jonas, a Morgan Stanley auto analyst, in a recent investment report. "No mayor wants to be the first elected official blamed for the death of a citizen by a robot," he wrote.
Little-By-Little
The likely path to acceptance is the introduction of autonomous features in regular cars - automatic braking systems, for example, or parking. These are already rolling out in some vehicles, and are likely to substantially cut accident rates.
The result of this little-by-little approach is that we may eventually end up in self-driving cars without realising it. But until then we should be accepting of the occasional robotic accident.
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"We cannot expect any technology, any solution to be perfect all the time," Raj Rajkumar, an autonomous vehicle researcher, told AP. "We live in a very uncertain world where lots of things happen."