What Are The Six Levels Of Autonomous Driving Technology?

The Society of Automotive Engineers has created a set of criteria that define a vehicle’s level of autonomy. Read on to learn more about the six levels of autonomous driving technology.

Cars that can drive themselves have always been a dream, but the automotive industry is working hard to make that dream become a reality. Already, some carmakers are claiming that their cars are ready to fully drive themselves, though legal and regulatory issues mean they cannot enable this technology for use at present.

The Society of Automotive Engineers (SAE), an American engineering group that has established technical standards for the automotive industry since 1905, defines six levels of autonomous vehicles, which describe the increasing levels of automation required for self-driving vehicles.

Read on to learn more about these definitions and discover where your car fits along this scale.

The Levels of Autonomous Driving
Level 0 – No Driving Automation

At Level 0, the driver has full responsibility for controlling the car – whether driven by a manual or automatic gearbox. There may be some electronic systems such as cruise control, but as these must be manually activated and deactivated by the driver, they are, therefore, not automated. Warning systems for blind spot or lane departure might be in place, as could be automatic emergency braking, but as they are only in use for a short time, they are only considered to be Level 0.

Level 1 – Driver Assistance

At Level 1 the car will go beyond passive warnings and offer at least one feature that provides some elements of steering, braking or acceleration support to the driver, in limited situations. Examples of these include automated lane-keeping when it detects the car drifting out of lanes, park assistance, where the car reverse parks without driver intervention, and adaptive cruise control, where the vehicle will accelerate and brake by itself to maintain distance to cars in front on the motorway.

Level 2 – Partial Driver Assistance

Level 2 introduces advanced driver assistance systems (ADAS). This means that the vehicle offers a combination of the Level 1 systems together so that it can steer, brake and accelerate itself in certain situations – and only on approved areas of the road. ADAS are there to support the driver, but they must be ready to step in at any time. As such, ADAS features are best considered to be “hands-off” rather than a full-self-drive system.

Level 3 – Conditional Driving Automation

When a Level 3 system is engaged the car will be fully autonomous – which means the human “driver” is now effectively a passenger. In certain areas, and under certain conditions, the car will steer, brake and accelerate entirely by itself, leaving the “driver” free to take their hands off the wheel and their eyes off the road.

However, when the vehicle requests, they must be ready to take full control – so taking a nap is not permitted. Level 3 driving requires a significant technological leap in sensor and AI capabilities over Level 2, and, while some manufacturers are awaiting regulatory approval, as of writing, no Level 3 vehicles are permitted anywhere in the world. 

Did you know? The word “automotive” comes from the Greek autos (self), and Latin motivus (of motion) and refers to any form of self-powered vehicle.

Level 4 – High Driving Automation

Level 4 is essentially a fully self-driving car and will not require a human driver in most circumstances. At this stage, nap-taking will be permitted. However, the full self-driving mode will only be possible in limited ‘geo fenced’ areas – where highly-detailed HD maps are available, and weather conditions permit. Speeds may also be limited.

There will still be the option for the driver to take over, but in a reverse of Level 2 and Level 3, this will only be available when it is deemed safe to do so. Level 4 will usher in driverless “robotaxis” and most cars with this level will fall into the ridesharing category. As such, once this stage is bedded in, it could introduce major changes in car ownership, as people see less need to take on the cost of having a vehicle on call at all times.

Level 5 – Full Driving Automation

A Level 5 is a completely automated car, that can travel anywhere there are roads, (or even off-road, depending on the type of vehicle) in all conditions. Many Level 5 vehicles will do away with steering wheels and pedals, as there will be no requirement for them.

The current state of play

Technology moves fast and the SAE has recently updated its levels of driving automation with further definitions. The SAE and the ISO (International Standards Organisation) are now clarifying that Level 0-2 should be referred to as “driver support systems” while Level 3-4 and 5 are used for actual “automated driving systems.” ISO 26262 functional safety standards are set to become more important.

In simple terms, Level 0, Level 1 and Level 2 mean that the human is still driving and bears legal responsibility, while the available features are just for driver support. At Level 3, Level 4 and Level 5 the human is not driving (but may be required to intervene at Level 3 under certain conditions) so these are often referred to colloquially as “hands-off, eyes off and brain off”. Indeed, at level 5 you could be watching a film, playing a game or even asleep at the wheel – except for a Level 5 vehicle where this isn’t possible as by definition there isn’t a wheel!

When will cars be able to drive themselves

There are many cars on the road today with Level 2 features, from most manufacturers such as Tesla, GM, Volvo, Mercedes, Audi and Renault. Level 3 carries with it some controversy as some believe it is very difficult to judge where the car can drive itself and when the human has to take over. That’s the view of Ford, who has said that it intends to bypass Level 3 and focus its research and development on Level 4. Honda, however, has launched a Level 3 capable car, but it only is allowed to operate it in Japan.

Currently, Tesla takes the mindshare for autonomous driving, but its so-called “AutoPilot” system is only a Level 2 system, while its “Full Self-Driving” system, which has been promised repeatedly for several years is, as of writing, in active beta testing by limited numbers of customers. Despite the name, this will be a Level 3 system once out of beta.

Level 3 will be possible on some highways in the U.S. and is due to be approved in the UK by the end of 2021. The latter will allow cars equipped with automated lane-keeping systems (ALKS) to take their hands off the wheel. However, it will be limited to 37mph (60km/h) so won’t be much help for long motorway journeys.

Either way, production-ready autonomous vehicles are moving at a pace, and the list of companies that support self-driving is increasing every year.