Advanced automotive-safety systems—including automatic emergency braking and lane-keeping assistance—are unreliable when it’s raining. These systems’ ­cameras and sensors struggle to identify obstructions, pedestrians, road markings and other vehicles through rain drops. That’s particularly troubling because low-visibility conditions are precisely when drivers rely on their vehicles’ safety systems the most.

Tests conducted by the American Automobile Association (AAA) in simulated moderate or heavy rainfall found that automatic emergency braking–equipped vehicles traveling 35 mph collided with stopped vehicles 33% of the time. These systems are supposed to bring vehicles to a halt before accidents occur. And vehicles equipped with lane-keeping assistance veered outside their lanes a significant 69% of the time.

Automakers and regulatory agencies typically test these advanced driver-­assistance systems under only ideal weather conditions, hiding these limitations.

What to do…

Continue to use common-sense driving strategies when visibility is poor, such as slowing down and increasing the distance between your vehicle and the one ahead.

Don’t use adaptive cruise control when significant rain, snow or ice is falling. Adaptive cruise control is supposed to maintain a safe distance behind the vehicle ahead, but it might fail to notice that that vehicle has slowed and/or fail to adjust to the longer stopping distances needed on slick roads.

Replace your wiper blades as soon as they start to leave visible streaks. If you’re having a hard time seeing through your windshield, your vehicle’s safety systems might be struggling, too—the cameras these systems rely on typically are positioned behind the windshield up high near the rear-view mirror.

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