WASHINGTON (Reuters) - Alphabet Inc said Wednesday its self-driving car project will expand testing to Kirkland, Washington later this month, the third city where it is testing autonomous vehicles.

A Google self-driving car is seen inside a lobby at the Google headquarters in Mountain View, California November 13, 2015. REUTERS/Stephen Lam

The company’s Google unit has conducted autonomous vehicle testing for six years in Mountain View, California, where it is based, and it expanded testing to Austin, Texas last summer.

Google said in a statement that one reason for the new site in the northwest United States is to gain experience in “different driving environments, traffic patterns, and road conditions.”

Kirkland has significant seasonal rain that allows for wet weather testing, along with hills that will allow testing of sensors at different angles and elevations.

Google began a few weeks ago driving a single Lexus RX450h SUV around a few square miles in North Kirkland to create a detailed map of the streets.

The company says its self-driving software has already been tested in over 1.4 million miles of autonomous driving.

Washington Governor Jay Inslee praised the testing. “We’re looking forward to seeing the cars on the road and understanding more about how self-driving cars might someday improve safety and provide traffic relief,” he said in the Google statement.

Last month, the U.S. Transportation Department said it may waive some vehicle safety rules to allow more driverless cars to operate on U.S. roads as part of a broader effort to speed up development of self-driving vehicles.

Major automakers, and technology companies led by Google, are racing to develop and sell vehicles that can drive themselves, but they have complained that safety rules are impeding testing and ultimate deployment of such vehicles.

The U.S. National Highway Traffic Safety Administration told automakers it is willing to exempt up to 2,500 vehicles industry-wide from some auto safety standards for up to two years in a move that could allow Google to get its self-driving cars on U.S. roads.

Safety regulators will write guidelines for self-driving cars within six months, Transportation Secretary Anthony Foxx said last month.