A study by AAA found that moderate to heavy rain can impact a vehicle’s safety system and lead to catastrophic consequences.
The automobile association put vehicles’ advanced driver-assistance systems through simulations that tested their performance in various scenarios during recent testing.
"The reality is people aren’t always driving around in perfect, sunny weather, so we must expand testing and take into consideration things people actually contend with in their day-to-day driving," said Greg Brannon, AAA’s director of automotive engineering and industry relations.
Researchers said they put automatic emergency braking and lane-keeping assistance systems through conditions that included bugs, dirt, and varying rainfall intensities.
The results of the trials surprised many, including officials at AAA.
AAA reported that vehicles equipped with automatic emergency braking systems traveling at 35 mph collided with the car in front of them 33% of the time, during moderate or heavy rainfall.
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The results were even worse when experts examined lane-keeping assistance programs under similar weather hazards.
AAA found that vehicles left their lanes 69% of the time when the lane-keeping assistance was engaged.
"Vehicle safety systems rely on sensors and cameras to see road markings, other cars, pedestrians and roadway obstacles. So naturally, they are more vulnerable to environmental factors like rain," Brannon said.
These safety systems, which were hard to find only a decade ago, are now growing in availability.
The National Safety Council reported in 2018 that 24% of new vehicles had some sort of lane-keeping assistance program, and 42% had automatic braking systems.
The growing usage of the systems has AAA cautioning drivers and manufacturers that there is still room for technological improvements.
"Fine-tuning their performance and providing drivers with a more consistent experience will go a long way in unlocking their true potential," Brannon said.
AAA strongly urges drivers to remain fully engaged and reminds everyone that there is no full-proof replacement to a human behind the wheel.