Self-driving cars: the levels of automation and where things stand
TUREFF• •0
Self-driving cars have been just a few years away for well over a decade. Some driverless services now carry paying passengers in certain cities, while the car on your driveway almost certainly still needs you to drive it. Understanding the official levels of automation helps cut through the marketing.
The SAE levels
The most widely used framework comes from SAE International in its standard J3016, which defines six levels. A key point is that the level describes a feature while it is engaged, not the car as a whole.
- Level 0: no driving automation. The driver does everything, although warning systems and momentary emergency braking may help.
- Level 1: driver assistance. The system helps with either steering or speed, such as adaptive cruise control, but not both at once. The driver does everything else.
- Level 2: partial driving automation. The system can steer and control speed together, for example on a motorway, but the driver must supervise constantly and be ready to take over immediately. Most advanced systems on sale to the public are here.
- Level 3: conditional driving automation. Within specific conditions, the system drives and monitors the road, and the person in the driving seat can look away but must take over when asked.
- Level 4: high driving automation. The system drives itself within a defined area or set of conditions and does not need a human to take over; if something goes wrong, it brings the vehicle to a safe stop. Robotaxis operating in mapped city zones fall here.
- Level 5: full driving automation. The system can drive anywhere, in any conditions a human could. No such system exists.
Where things stand
The picture is changing quickly, so check current news for your area.
- Robotaxis. Waymo, owned by Alphabet, runs fully driverless ride-hailing services in a growing number of US cities and has announced plans for international markets. Several companies in China also operate driverless services. These work within defined service areas that are extended gradually.
- Level 3 in private cars. A small number of manufacturers have gained approval for Level 3 systems in some markets, typically limited to certain motorways, speeds and conditions.
- Driver assistance. Many systems sold with ambitious names remain Level 2, meaning the driver is fully responsible at all times. Regulators in several countries have investigated crashes involving drivers who over-trusted such systems.
The legal side
Laws are being rewritten to decide who is responsible when a car drives itself. In Great Britain, the Automated Vehicles Act 2024 sets out a framework under which, when an authorised self-driving feature is in control, the company behind it rather than the person in the driving seat is responsible for how the car drives. The government has said it wants pilots of self-driving taxi and bus-like services before the full regime comes in, with detailed rules being developed in stages. Other countries are taking their own approaches.
Why it is taking so long
- Rare situations. Roadworks, emergency vehicles, unusual pedestrians and bad weather create endless edge cases.
- Proving safety. Showing that a system is safer than a careful human driver requires vast amounts of driving data and careful analysis.
- The handover problem. People are poor at supervising automation that works most of the time, which makes Level 2 and Level 3 tricky.
- Cost and scale. Sensors, mapping, remote support and maintenance must become cheap enough to run profitably.
What it means for you
- If you drive a car with assistance features, read the manual, know its level and keep your hands and attention where it requires.
- Do not rely on a product's name; check what the manufacturer and the law say about your responsibilities.
- Expect driverless services to appear city by city rather than everywhere at once.
Have you ridden in a driverless taxi or used advanced driver assistance? Share your experience in the comments.