Definition: Levels of AD
Fully automated driving will not happen overnight. It is a revolution through evolution: cars gradually learn how to drive themselves. Therefore we need different terms for different levels of automation. This is an overview of how they are defined.
Highly automated, autonomous, driverless, self-driving - there are many words to describe future visions for the automobile. So many, in fact, that the discourse on vehicle automation sometimes resembles Babylonian language confusion if you look at it in detail.
Different publications in various countries use differing terminologies. In popular media it has become common to use words like "driverless" as an umbrella term for all kinds of vehicles that, in fact, differ greatly in their levels of automation. We believe, however, that we need to know what we talk about when we talk about automation. That is why this article attempts to give an overview of the basic definitions and terminology as it was laid down by the key institutions.
How relevant entities define AD
In January 2014, the SAE - the Society of Automotive Engineers - classified the future of the automobile. They developed a harmonized system to describe six degrees of automated driving: from zero automation to full automation. It has since become one of the most widely used systems of classification.
This technical taxonomy describes which tasks the vehicle carries out, and which requirements the driver has to fulfill. It includes both longitudinal (speed, acceleration and braking) and lateral (steering) tasks as well as monitoring the driving environment.
Such a system serves to educate the wider community as to the step-wise progression of automated driving. It also simplifies communication and makes it easier for technicians and politicians to collaborate - everyone can be on the same page.
But the SAE is not alone in this effort: other institutions have also put forth classification systems, sometimes derived from one another. Among those entities are the US National Highway Traffic Safety Administration (NHTSA); the German Association of the Automotive Industry (VDA) and the Germany Federal Highway Research Institute (BASt). The good news is though, most of these correspond to a high degree. This overview summarizes the common aspects of the original classifications:
How we at 2025AD see it
The table proves that there is a lot of mutual ground in classifying the degrees of automation. The major differences lie in labeling the levels. The most striking one: while some organizations have traditionally called level 4 “fully automated driving”, others speak of level 5 as “full automation”.
On 2025AD.com, we generally refer to level 4 as “fully automated driving (in driving scenario x)”. For level 5 we use terms like “driverless”, “autonomous” or “self-driving”. We do so in order to clarify an important distinction:
Level 4 is a tangible goal – one that we believe can be achieved until the year 2025. At level 4, the human driver can hand over full control to the vehicle in certain situations. We will, for instance, be able to watch TV in the driver’s seat while cruising on a highway – without having to worry about being called back to driving duty. However, the driver is still required to be in the vehicle. And most importantly: he can always hit the off-button and drive manually, if he wants to. It remains his choice.
Level 5, however, brings us into the more distant future. A future in which cars may drive themselves in all use cases, completely without humans on board. We believe that an introduction of level 5 automation in passenger cars with a license for all public roads is still a considerable way off. Experts do not see this being achieved within the next 15 years. (We are, however, seeing earlier versions of autonomy in particular low-speed scenarios or use cases on private grounds.)
Why different articles on 2025AD might use different terms
The 2025AD.com team adheres to the aforementioned definition. However, our interview partners, guest authors, users or quoted media sources might use the terms slightly differently. We at 2025AD.com will always try to ensure that everybody is on the same page when discussing with each other.
Our hope is that together we reach a better understanding of what we talk about when we talk about automation!
Which terminology do you see as the most accurate for the levels of automated driving? Comment and let us know!