Programming a computer to understand and navigate roads designed for human drivers is hard. Rarely, however, do we get to see just how many things can go wrong when an autonomous vehicle encounters a situation it doesn't know how to tackle. A 35-minute video from Joel Johnson (via Autoblog), a YouTuber who shares clips of his trips with Waymo One in Arizona, offers a rare glimpse into a perfect storm of errors. About 12 minutes into the video, Johnson's car wants to turn right onto a multi-lane street. Unfortunately for Waymo Driver, the rightmost lane was closed, with construction cones marking the obstruction.

Not everyone is excited to see self-driving cars on the road. Police in Arizona have recorded 21 incidents in the past two years concerning vigilante citizens who have hurled rocks, pointed guns at and slashed the tires of Waymo's autonomous vans. In other cases, people stood in front of the vehicles to prevent them from driving, yelled at them, chased them or forced them off of the road, according to The Arizona Republic. Police in Arizona have recorded 21 incidents in the past two years concerning vigilante citizens who have cast rocks, pointed guns at and slashed the tires of Waymo's autonomous vans The human monitors who sit as passengers in the vehicles often don't call police, however, as they're trained to handle harassment. Even when, on August 1st, a test driver in a self-driving vehicle encountered a man aiming a handgun at him, Waymo waited several days to call the police.

Waymo, the self-driving car company created by Google, is pulling the human backup driver from behind the steering wheel and will test vehicles on public roads with only an employee in the back seat. The company's move -- which started Oct. 19 with an automated Chrysler Pacifica minivan in the Phoenix suburb of Chandler, Ariz. Waymo -- owned by Google's parent company, Alphabet Inc. -- is in a race with other companies such as Delphi, General Motors, Intel, Uber, Apple and Lyft to bring autonomous vehicles to the public. The companies say the robot cars are safer than human drivers because they don't get drowsy, distracted or drunk. Waymo has long stated its intent to skip driver-assist systems and go directly to fully autonomous driving.

Sam Abuelsamid, senior analyst for Navigant Research, says Waymo's tests without a human backup are the first to his knowledge on public roads at normal speeds. The company picked Phoenix because weather conditions are ideal for testing with no snow and little rain, he said, adding that Waymo knows its system isn't ready yet for inclement weather even with camera, radar and laser sensors.