Not all automatic braking systems are equal. Some are designed to prevent crashes entirely, while others are only meant to reduce the severity of a collision. What kind does your car have? Perhaps your car doesn't yet stop itself, but with most major car makers signed on to add automatic emergency braking to their cars by September 1, 2022, it’s likely that your next car might. And knowing how your car behaves might save your life.
The AAA has published new research on the efficacy of different kinds of automatic braking systems, and the beliefs of Americans about what those automatic systems are actually supposed to do.
"AAA found that two-thirds of Americans familiar with the technology believe that automatic emergency braking systems are designed to avoid crashes without driver intervention," said AAA managing director of automotive engineering and repair John Nielsen in a statement.
And yet, in many cases, that’s just not true. While some cars are designed to completely stop themselves in case of emergency, many are only meant to reduce speed to make any collision less severe.
One problem with semi-autonomous cars is that we’re still in charge. If you’re riding in a self-driving car, you know you’re supposed to sit back and let the car do the work. But that hasn’t happened yet. Instead, we’re in a limbo where we’re not always sure who’s taking care of what. Just how will the car behave if you drift out of your lane? If the car in front stops suddenly? If a pedestrian walks out into your path?
To find out the truth, the AAA took five 2016 model cars out and ran them through more than 70 trials. These included tests that were within the guidelines set by the manufacturers and also tests that went way beyond these limits. The results showed that if you’re interested in a car that can save your life, then you should opt for one that is designed to prevent crashes, rather than one simply meant to lessen crash severity, because the difference in performance in real-life situations is huge.
When tested under 30 mph, crash-prevention cars avoided 60% of crashes. Cars with severity-reduction systems also did pretty well in total avoidance, managing to completely avoid crashes in 33% of tests. When the pressure was put on, though, the gap grew.
At speeds over 45 mph, the crash-prevention cars managed to reduce speeds by 74% overall, and to completely avoid 40% of crashes. The cars with simpler severity-reduction systems fared way worse, and "were only able to reduce vehicle speed by 9% overall."
These results can be taken several ways. One is that, if driving at safe speeds in cities, then even the simpler automatic braking systems offer a real boost to safety. "When traveling at 30 mph," said Automobile Club of Southern California’s Automotive Research Center’s Megan McKernan in a statement, "a speed reduction of just 10 mph can reduce the energy of crash impact by more than 50%."
But in real life, nobody drives under 30 mph (though they should!), and at real-world speeds, a car designed only to reduce the severity of a collision has little effect. Combine this with the possibility that people will come to rely too heavily on their cars to keep them safe, freeing them up for the important business of texting instead of concentrating on the road ahead, and the lesser automatic braking systems might actually make things worse.
Even so, the AAA recommends that buyers consider automatic braking systems, with one big caveat. "With the proliferation of vehicle technology," says Nielsen, "it’s more important than ever for drivers to fully understand their vehicle’s capabilities and limitations before driving off the dealer lot."
That seems optimistic, given how few drivers manage to figure out how something as simple as using their turn signal, and so we return to that limbo, where people act like their cars are autonomous, even while they’re not. Viewed like this, the fully driverless car revolution can’t come soon enough.
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