Waymo taxis have driven millions of miles without a human behind the wheel. An autonomous vehicle is a car or truck capable of navigating without human intervention. It uses cameras, radar, lidar, and detailed maps to perceive the world and make driving decisions.

The Society of Automotive Engineers defines six levels of autonomy. Level 0 is no automation. Level 5 is full automation with no steering wheel. Most consumer cars today are Level 1 or 2 — they assist with lane keeping and adaptive cruise control, but the driver must stay alert. Level 4 and 5 vehicles are still limited to specific areas and conditions.

Key sensors

• Cameras: read signs, lanes, and obstacles
• Radar: measures distance and speed
• Lidar: builds a 3D map with laser pulses
• GPS and inertial sensors: track position

The technology works. The hard part is the edge cases. A construction worker waving traffic through. A child chasing a ball. A faded lane marker in the rain. Humans handle these without thinking. Machines need explicit training for each one.