Google's self-driving cars are heading down the dusty roads of Phoenix.
On Thursday, the company announced via Google+ that its Lexus RX450h SUVs have started driving around the Arizona capital. The goal at this point is for Google's test drivers to generate a map of the streets, lane markers, traffic lights and curbs in and around Phoenix, according to the company. That information will then be fed into the technology embedded in the autonomous cars so they know how to navigate the city on their own.
Proving that self-driving vehicles can share the roads with human drivers is a challenge for Google and other companies testing the technology. With tech firms and automakers racing to hit the roads with self-driving cars in the next several years, showing that these vehicles can handle diverse conditions in a variety of cities is critical to widespread adoption.
"The Phoenix area has distinct desert conditions, which will help us better understand how our sensors and cars handle extreme temperatures and dust in the air," Jennifer Haroon, head of business operations for the Google Self-Driving Car project, said in a statement. "Driving in new cities enables our engineers to further refine our software and adapt to these different environments."
Phoenix is the fourth US city where Google is testing its autonomous cars. The vehicles have already been driving around Google's home base of Mountain View, California. Google added Austin, Texas, to its self-driving lineup in July. Kirkland, Washington, became the third locale so the company could test the city's wet weather conditions.
Google's self-driving cars have been involved in accidents, all considered minor and all except one blamed on the human driver of the other car. In March, Google admitted some responsibility for an accident in which one of its autonomous vehicles hit the side of a bus while trying to change lanes.
In February, the National Highway Traffic Safety Agency declared that a self-driving vehicle system would be considered the driver in terms of how future autonomous cars would be designed. But the agency must still address key questions, such as who's responsible for accidents. It will host a news conference Friday to discuss proposed guidelines for automated vehicles.