You should take Waymo's numbers with a healthy dose of skepticism. They are very selective about which disengagements they report. Here are the details from the

You should take Waymo's numbers with a healthy dose of skepticism. They are very selective about which disengagements they report. Here are the details from their 2017 letter to the DMV: This report covers disengagements following the California DMV definition, which means “a deactivation of the autonomous mode when a failure of the autonomous technology is detected or when the safe operation of the vehicle requires that the autonomous vehicle test driver disengage the autonomous mode and take immediate manual control of the vehicle.” Section 227.46 of Article 3.7 (Autonomous Vehicles) of Title 13, Division 1, Chapter 1, California Code of Regulations. Waymo has developed a robust process to collect, analyze and evaluate disengages for this report. We set disengagement thresholds conservatively for our public road testing. The vast majority of disengagements are not related to safety. Our test drivers routinely transition into and out of autonomous mode many times throughout the day, and the self-driving vehicle’s computer hands over control to the driver in many situations that do not involve a failure of the autonomous technology and do not require an immediate takeover of control by the driver. To help evaluate the safety significance of disengagements, Waymo employs a powerful simulator program. In Waymo’s simulation, our team can “replay” each incident and predict the behavior of our self-driving car if the driver had not taken control of it, as well as the behavior and positions of other road users in the vicinity (such as pedestrians, cyclists, and other vehicles). Our engineers use this data to refine and improve the software to ensure the self-driving car performs safely. https://www.dmv.ca.gov/portal/wcm/connect/42aff875-7ab1-4115-a72a-97f6f24b23cc/Waymofull.pdf https://www.dmv.ca.gov/portal/wcm/connect/42aff875-7ab1-4115...