What happens if the Waymo computer fails?

You buckle into the back seat of a Waymo, the doors close and there is nobody behind the wheel. For some riders, that empty driver's seat still takes a little getting used to. Then another thought creeps in. What happens if the Waymo computer doing all the driving suddenly fails?

Waymo has now given us its first detailed look at the powerful computing system hidden inside its driverless vehicles. The company describes a machine built to make decisions in milliseconds without waiting for the cloud or a remote human driver.

More importantly, Waymo says it built backups into the system because there is no person sitting up front who can grab the wheel. So, what actually happens when the electronic driver has a problem?

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TERRIFIED PASSENGERS FILM WAYMO AUTONOMOUS VEHICLE DRIVING INTO LIVE FIREWORKS IN SAN FRANCISCO

Waymo says its newest compute system works somewhat like two independent engines. During normal driving, both computing systems can run full workloads in parallel. If one develops a fault, Waymo says the other can take over.

That gives the vehicle another electronic driver already onboard rather than forcing it to wait for someone miles away to intervene. Waymo's broader safety documentation goes further. The company says a secondary onboard computer can bring a vehicle to a safe stop if it detects a failure in the primary system. The vehicle also has backup braking and redundant steering hardware. Separate power sources support critical driving systems.

The priority in a serious failure is to keep the vehicle under control and reach a safe state. That could mean stopping rather than finishing your trip. For a rider, that is probably the most important part of Waymo's new disclosure.

A Waymo takes in a huge amount of information as it moves. Its cameras feed images into the onboard system. Lidar uses laser pulses to create a detailed picture of the vehicle's surroundings. Radar helps measure how far away objects are and how quickly they are moving. Waymo's latest sixth-generation sensor system uses 13 cameras along with lidar and radar sensors.

The computer then has to make sense of all that information fast enough to steer, brake or react to something entering the road. Waymo says those driving decisions happen entirely onboard. That point is important for anyone who has wondered whether a robotaxi needs to send everything to a giant data center before making a turn. It does not. The onboard computer handles the immediate driving workload itself. According to Waymo, it has increased its raw computing power about 20 times over the past eight years. That extra muscle helps shrink the time between seeing something and reacting to it.

Waymo also revealed a new custom 5-nanometer ASIC. ASIC stands for application-specific integrated circuit. Forget the jargon for a moment. Think of it as a chip Waymo designed for a very specific job inside its vehicles rather than buying a general-purpose processor and asking it to do everything.

The chip handles raw information flowing in from the vehicle's sensors. It helps process camera, lidar and radar data before that information reaches other parts of the driving system. Waymo says the ASIC delivers more than 1,000 TOPS of machine-learning performance. TOPS means trillions of operations per second.

That sounds like something printed on the side of a computer box. The practical idea is much easier to understand. Waymo wants the car to recognize what it sees and respond with as little delay as possible. For example, the system can process footage from 13 high-resolution cameras at the same time. Waymo says its technology also improves what the cameras can detect in low light.

Computing redundancy only covers part of the problem. Imagine the backup computer works perfectly, but the vehicle suddenly loses its normal braking hardware. Waymo says it has a secondary braking system that can bring the vehicle to a safe stop.

Steering also has redundant hardware. Waymo says separate controllers and power supplies support its secondary steering system. Then there is electricity. Critical driving systems have independent power sources so a single power problem does not automatically knock out everything the vehicle needs to operate.

Waymo has been building these layers into its autonomous vehicles for years. The company has previously described testing scenarios involving hardware faults, power problems and software failures. Its vehicles continually check their own systems while driving. That approach makes sense when the human backup has been removed from the equation.

THIEF USES WAYMO AS A GETAWAY CAR

This is one of the biggest misconceptions about driverless robotaxis. There is no employee sitting in an office with a steering wheel and pedals waiting to take control of your Waymo.

Waymo does use what it calls Remote Assistance. However, the company says those employees provide information rather than remotely driving the vehicle. If the Waymo Driver encounters an unusual situation, it can request additional context from a remote agent. The car can then decide whether to use that information.

Waymo says remote agents do not continuously watch every vehicle. The automated driving system remains responsible for controlling the car. So, if the onboard computer develops a hardware fault, a remote employee does not suddenly become your driver. The backup has to exist inside the vehicle.

Absolutely. Backup computers help protect against hardware failures. They cannot prevent every problem a driverless vehicle may encounter. A computer can be functioning exactly as designed while the software struggles to interpret an unusual road situation.

We have already seen why that deserves attention. CyberGuy recently reported on a Waymo software recall involving 3,871 vehicles after robotaxis entered closed freeway construction zones in Phoenix and the San Francisco Bay Area. That problem involved how the automated driving system handled changing road conditions rather than a dead onboard computer.

It is a useful reminder that redundancy addresses one category of risk. Autonomous driving also depends on perception, decision-making and the software correctly understanding what is happening outside the car. Waymo continues to refine those systems as its fleet grows.

The company's latest published safety analysis covered more than 220 million fully autonomous miles through March 2026. Waymo says its vehicles experienced fewer serious or fatal injury crashes than human drivers operating in comparable areas during that analysis. Those figures come from Waymo's own safety research.

A driverless vehicle has a very different job from the driver-assistance technology you may already have in your own car. Your vehicle may warn you about another car in your blind spot. It might help keep you centered in a lane. You remain responsible for driving.

A fully autonomous Waymo has to handle the complete driving task within the areas where the service operates. There may be nobody in the vehicle capable of taking over. That changes the engineering challenge.

The computer needs enough performance to understand what is happening around the vehicle almost immediately. It also has to survive years of vibration and temperature changes inside a working car.

Waymo says its computing hardware connects to the vehicle's liquid-cooling system to help maintain performance in very hot or cold conditions. This computer effectively lives in one of the roughest offices imaginable. It gets shaken around all day while making decisions that can affect everyone around it.

You may already have taken a Waymo, or you could be considering your first ride. Either way, knowing what to do if you need help or the vehicle stops unexpectedly can make the experience less confusing.

If you are thinking about taking your first Waymo ride, the empty driver's seat may look like there is no backup. Waymo's new disclosure shows that the company has tried to move that backup into the hardware itself. If one computing system develops a fault, another system is designed to take over. Other backup systems can help with critical functions such as stopping the vehicle or maintaining steering. That may make some people more comfortable climbing into the back seat.

Still, redundancy should never be confused with perfection. A second computer lowers the danger from certain hardware failures. It cannot guarantee that every unusual road situation will go exactly as planned. If a Waymo encounters trouble during your ride, you can also reach Rider Support from inside the vehicle or through the Waymo app. Waymo says Rider Support can assist passengers during a trip and in an emergency. For me, knowing how the backup works makes that empty driver's seat a little easier to understand.

The giant processing numbers and custom chips are impressive, but the part I care about most happens when something goes wrong. If I am sitting in the back seat of a car with no driver, I want to know there is another system ready before the first one fails. Waymo's approach of running redundant compute, combined with backup vehicle controls, gives us a much clearer picture of how the company thinks about that problem. I also would not treat any of this as a reason to stop asking tough questions about autonomous vehicles. Hardware redundancy can protect against a failed component. Real streets introduce another challenge because software still has to understand construction crews, unpredictable drivers and situations engineers may never have anticipated. The more robotaxis spread into our everyday life, the more transparency I want about what happens during those moments. Waymo opening up the trunk and showing us some of the technology inside is useful. Now we need to keep watching how that technology performs on the road.

Would knowing there is a second computer and backup braking make you more willing to climb into a driverless Waymo, or would you still want a human in the front seat when something goes wrong? Let us know by writing to us at Cyberguy.com

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