The era of self-driving cars is rolling toward reality, with the promise that autonomous vehicles will free up our commute time and make our roads much safer. Google, which is developing its own self-driving car, announced this week that its vehicles could be on our roads within the next five years. Analysts at IHS Automotive predicted in a recent report that nearly 54 million self-driving cars will be on the roads globally by 2035 — and that nearly all vehicles will be self-driving sometime after 2050.
The transition won’t be easy, though. A new report from the University of Michigan’s Transportation Research Institute says that road safety will actually worsen during the transitional period, which unfortunately could be indefinite.
“When both conventional and self-driving vehicles would be on the road, the risk for conventional vehicles could be elevated,” wrote researchers Brandon Schoette and Michael Sivak in the report.
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There are some obvious benefits to self-driving vehicles: they can improve the mobility of those who don’t currently drive and they will reduce emissions because congestion and idling will be greatly minimized.
In a society where only self-driving cars will be on the roads, safety will also be dramatically improved, even if the expectation of zero fatalities isn’t realistic.
Not all traffic accidents are caused by drivers, so self-driving vehicles couldn’t eliminate all crashes, like those caused by jaywalking pedestrians, for example, or by vehicular defects such as failed brakes or environmental hazards such as a sudden dense fog, the authors noted.
Overall, they write, given the complexity of the sensing hardware and of the information-processing software, it is reasonable to expect that vehicular failures would likely occur more frequently on self-driving vehicles than on conventional vehicles.
Human drivers might also have difficulties sharing the road with autonomous cars. “In many current situations, interacting drivers of conventional vehicles make eye contact and proceed according to the feedback received from other drivers. Such feedback would be absent in interactions with self-driving vehicles,” the authors wrote.
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Even so, eliminating the human factor from driving isn’t entirely a positive. Some of the lowest rates of fatalities per distance driven are registered with middle-aged drivers who benefit from their experience behind the wheel and from their predictive knowledge about the likely intentions of other road users.
“To the extent that not all predictive knowledge gained through experience could exhaustively be programmed into a computer, it is not clear whether computational speed, constant vigilance and lack of distractibility of self-driving vehicles would trump the predictive experience of middle-aged drivers,” the report said.
The other problem is that it’s hard to know just how long self-driving vehicles and conventional vehicles will share the road during the technological transition. “It takes a long time to turn over the U.S. fleet of light-duty vehicles, with the average vehicular age currently being 11.4 years,” according to the report.
The authors add that the overlapping period might last indefinitely if humans refuse to give up their cars, but Google and major car makers might have something to say about that.
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