Waymo’s Closed-Course Facility

Waymo’s Private Test Track

Waymo has set up a private, 91-acre, closed-course testing facility in California specially designed and built for Waymo’s own unique testing needs. This private facility, nicknamed “Castle,” is set up like a mock city, including everything from high-speed roads to suburban driveways to a railroad crossing. Waymo’s team uses this and other closed-course facilities to validate new software before it’s released to its fleet of vehicles on the road.

New software is pushed to a few vehicles first so that Waymo’s most experienced drivers can test the new software on its private test track.

At “Castle,” engineers can stage challenging or rare scenarios that might take hundreds of thousands of driving miles to encounter on public roads, all so Waymo can gain experience with unusual situations.

Waymo is Tested for Safety In More Than 20,000 Scenarios

Waymo uses the 37 pre-crash scenarios based on the almost 6 million police-reported light vehicle crashes that NHTSA recommends for testing as a starting place. Each of these individual tests recreates a distinct driving scenario at its closed-course facility and allows Waymo to analyze the vehicles' response. Waymo then uses its simulator to test these scenarios further and improve its overall software capabilities.

Examples of scenarios staged at the closed-course facility include:

  • An aggressive driver barreling out of a driveway
  • A pedestrian suddenly emerging from a parked car
  • People jumping out of canvas bags or porta-potties on the side of the road
  • Skateboarders lying on their boards
  • People throwing stacks of paper in front of Waymo’s sensors

Engineers have developed more than 20,000 scenarios at "Castle." These scenarios are then fed to Waymo’s simulator so that they can each be tested hundreds of times with slight variations.

This “structured testing” is key to accelerating the progress of our technology and ensuring safety of Waymo’s vehicles in both everyday and challenging driving situations.

Learn More

Stay informed on how self-driving cars have the potential to improve our lives.

Your email has been submitted succesfully. Unexpected error, please try again.