In June 2015, the team announced that their vehicles had driven over , stating that this was "the equivalent of 75 years of typical U.S. adult driving", and that in the process they had encountered 200,000 stop signs, 600,000 traffic lights, and 180 million other vehicles. Google also announced its prototype vehicles were being road tested in Mountain View, California. During testing, the prototypes' speed did not exceed and had safety drivers aboard. As a consequence, one of the vehicles was stopped by police for impeding traffic flow. In 2015, Google expanded its road-testing to Texas, where regulations did not prohibit cars without pedals and a steering wheel. Bills were introduced by interested parties to similarly change the legislation in California. Google took its first driverless ride on public roads in October 2015, when Mahan took a 10-minute solo ride around Austin in a Google "pod car" with no steering wheel or pedals. In 2016, the company expanded its road testing to the dry Phoenix, Arizona, area, and Kirkland, Washington, which has a wet climate. In May 2016, the company opened a 53,000 square foot self-driving technology development center in Novi, Michigan. , Google had test driven its fleet of vehicles, in autonomous mode, a total of . In August 2016 alone, their cars traveled a "total of 170,000 miles; of those, 126,000 miles were autonomous (i.e., the car was fully in control)". Beginning of 2017, Waymo reported to California DMV a total of 636,868 miles covered by the fleet in autonomous mode, and the associated 124 disengagements, for the period from December 1, 2015, through November 30, 2016. In November 2017, Waymo altered its Arizona testing by removing safety drivers in the driver position from their autonomous Chrysler Pacificas. The cars were geofenced within a 100 square mile region surrounding Chandler, Arizona. Waymo's early rider program members were the first to take rides using the new technology. Waymo began testing its level 4 autonomous cars in Arizona for several reasons: good weather, simple roads, and reasonable autonomous vehicle laws. Users hail vehicles through the Waymo app. They also have access to an onboard support system that can connect riders to a Waymo agent. In 2017, Waymo began weather testing in Michigan. Also, in 2017, Waymo unveiled its test facility, Castle, on 91 acres in Central Valley, California. Castle, a former airbase, has served as the project's training course since