AAA finds driverless cars don't fare any better than us on slick roads

If driving in wet weather is challenging, take heart. Self-driving cars aren't doing much better.

Recent tests conducted by the American Automobile Association show driverless cars in simulated moderate to heavy rain, traveling at 35 miles an hour crash about a third of the time.

"Inclement weather, anywhere from moderate to heavy rain, can have a big impact on the performance of vehicle safety systems and their ability to perform effectively on the road," said AAA spokesman Aldo Vazquez.

The tests also revealed that lane-keeping assistance technology failed 69% of the time in wet weather.

Vehicle safety systems, often called Advanced Driving Assistance Systems or ADAS, are often tested under more optimum weather conditions, not in harsher weather like the Bay Area is seeing this week.

The tests indicated the sensors and cameras in the driverless cars didn't see the vehicles in front of it in time to stop.

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"The optical cameras are not going to be able to detect things when it is pouring, it's raining or it's foggy," said Fred Barez, an engineer and researcher at San Jose State University. 

He says the driverless cars rely on a host of technologies including optical and thermal imaging cameras, lidar, and sonar.

"We are not there because installing all these cameras is going to cost money. The car companies are going to be concerned with the economies here. How many sensors do I put in and keep my car company's costs down? And what is going to be the demand for autonomous vehicles," Barez said.

Electrical engineers at UC San Diego last year announced technology that worked in foggy weather. But not in rain.

Barez said it will be at least a decade before all the necessary technology is truly ready.

"With all of those technologies being developed, we are moving in the right direction. But we haven't gotten to the end of the tunnel yet," he said.