AAA Oregon warns: Driver assist features lose performance in poor weather, pose safety risk

'As drivers, we cannot give up the task of driving'

BEND, Ore. (KTVZ) -- New research from AAA finds that rain diminishes the performance of advanced driver assistance systems, such as automatic emergency braking and lane-keeping assistance.

Vehicle safety systems, also known as advanced driver assistance systems, or ADAS, are typically evaluated in ideal operating conditions. However, AAA believes testing standards must incorporate real-world conditions that drivers normally encounter.

“We can’t just test these things on sunny, dry roads and think, 'Okay, they’re good to go,'" AAA Oregon/Idaho spokeswoman Marie Dodds said Wednesday.

AAA, in collaboration with the Automobile Club of Southern California’s Automotive Research Center, simulated rain and other environmental conditions (bugs and dirt) to measure impact on the performance of ADAS like automatic emergency braking and lane keeping assistance.

During closed-course testing, AAA simulated rainfall and found that test vehicles equipped with automatic emergency braking traveling at 35 mph collided with a stopped vehicle one-third of the time. Lane-keeping assistance didn’t fare any better, with test vehicles departing their lane 69% of the time.

“We have to really look into how these systems perform when it's raining, when it’s snowing," Dodds said. "What happens when there’s a bug in the sensor or dirt in the camera. How is that going to impact these systems?”

To simulate rainfall, AAA engineers designed a system using a reservoir to hold water, a high-pressure pump for a consistent flow of water and a precision injector nozzle to spray the windshield. This system was secured in the cargo area of the test vehicle and was connected to a nozzle positioned above the windshield so that the spray pattern covered the entire windshield. It should be noted that water sprayed by this system did not reach the pavement or interact with the test vehicle’s tires.

"Automatic emergency braking didn’t work, and the car slammed into the stalled vehicle that was in front of it,” Dodds said of the various tests conducted.

Although testing was done in rainy conditions, Dodds said the same results can be applied for areas that experience snowfall.

Many people rely on driver assist features, and Dodds said they can be useful, but strongly urges drivers to always pay attention. No matter how advanced you feel the features may be, adding these systems can’t replace an alert driver.

“As drivers, we cannot give up the task of driving," she said. "we can’t be complacent behind the wheel and do other things."