Problems with automatic braking

New test results from AAA reveal that automatic emergency braking systems – the safety technology that will soon be standard equipment on 99 percent of vehicles – vary widely in  performance.

“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 Chuck Mai, spokesman for AAA Oklahoma. “The reality is that today’s systems vary greatly in performance, and many are not designed to stop a moving car.”

All the systems tested by AAA are designed to apply the brakes when a driver fails to engage. However, those that are designed to prevent crashes reduced vehicle speeds by nearly twice that of those designed to lessen crash severity. While any reduction in speed offers a significant safety benefit to drivers, AAA warns that automatic braking systems are not all designed to prevent collisions and urges consumers to fully understand system limitations before getting behind the wheel.

One type of crash that automatic emergency braking systems are designed to help drivers avoid is rear-end collisions. National Highway Traffic Safety Administration says rear-end collisions account for nearly one-third of all traffic crashes. These crashes took 1,966 lives in 2014 and injured 521,668 more.

In partnership with the Automobile Club of Southern California’s Automotive Research Center, AAA evaluated five 2016 model-year vehicles equipped with automatic emergency braking systems for performance within system limitations and in real-world driving scenarios that were designed to push the technology’s limits. Systems were tested and compared based on the capabilities and limitations stated in the owner’s manuals and grouped into two categories — those designed to slow or stop the vehicle enough to prevent crashes, and those designed to slow the vehicle to lessen crash severity. After more than 70 trials, tests reveal:

  • In terms of overall speed reduction, the systems designed to prevent crashes reduced vehicle speeds by twice that of systems that are designed to only lessen crash severity (79 percent speed reduction vs. 40 percent speed reduction).
  • With speed differentials of less than 30 mph, systems designed to prevent crashes successfully avoided collisions in 60 percent of test scenarios.

Surprisingly, the systems designed to only lessen crash severity were able to completely avoid crashes in nearly 33 percent of test scenarios.

  • When pushed beyond stated system limitations and proposed federal requirements, the variation among systems became more pronounced.

When traveling at 45 mph and approaching a static vehicle, the systems designed to prevent crashes reduced speeds by 74 percent overall and avoided crashes in 40 percent of scenarios. In contrast, systems designed to lessen crash severity were only able to reduce vehicle speed by 9 percent overall.