SAE Levels of Driving Automation

Orange car operating at Level 1 of the SAE levels of driving automation

It’s always useful to get things right. When approaching any subject, it remains crucial to possess enough information necessary to make enlightened decisions. Unfortunately, people still get things wrong, and, when it comes to certain subjects, almost everyone gets everything wrong.

For example, self-driving cars, as expected with an emerging, fascinating technology, are getting a great deal of attention, but the comprehension of their fundamentals by the public varies troublesomely.

In truth, you’re not really supposed to call them “self-driving cars.” In fact, the terms “driverless cars” and “autonomous vehicles” are inaccurate as well, at least according to SAE J 3016-2018: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles.

Instead, SAE J 3016-2018 (which is not a specification and imposes no requirements) recommends using the terms “driving automation” and “driving automation system.” As discussed in the section of this document dedicated entirely to deprecated terms, vernacular terms like autonomous, driving modes, self-driving, unmanned, or robotic are often used inconsistently and confusingly to characterize driving automation systems and vehicles equipped with them. Since automation is the use of electronic or mechanical devices to replace human labor, it is the appropriate term and its usage can avoid confusion, misunderstanding, and diminished credibility.

If you examine the usage of “driving automation system,” you can clearly see that the term “vehicle” has been excluded. In fact, SAE J 3016-2018 recommends against using terms that make vehicles, rather than driving, the object of automation. The rationale behind this is that doing so can lead to confusion between vehicles that can be operated by a human driver and an automated driving system (ADS).

Self driving car targeting objects with SAE automation specifications

Most notably, SAE J 3016-2018 sets forth the levels of driving automation, which have come to be known as the SAE Levels. These levels have reached mainstream and official recognition, even being referenced in the US Department of Transportation’s Comprehensive Management Plan for Automated Vehicle Initiatives. To comprehend these levels, it is pretty important to have a solid grip on some of the key terms outlined in the SAE J 3016-2018 document.

These include the dynamic driving task (DDT), or “all the real-time operational and tactile functions required to operate a vehicle in on-road traffic.” Next is operational design domain (ODD), or “the specific conditions under which a given driving automation system or feature thereof is designed to function.” And then there’s the automated driving system (ADS), which encapsulates all the hardware and software collectively capable of performing the entire DDT on a sustained basis.

With these concepts in mind, the six SAE Levels of Driving Automation are as follows:

Level 0 – No Driving Automation

The performance by the driver of the entire DDT. Basically, systems under this level are found in conventional automobiles.

Level 1 – Driver Assistance

A driving automation system characterized by the sustained and ODD-specific execution of either the lateral or the longitudinal vehicle motion control subtask of the DDT. Level 1 does not include the execution of these subtasks simultaneously. It is also expected that the driver performs the remainder of the DDT.

Level 2 – Partial Driving Automation

Similar to Level 1, but characterized by both the lateral and longitudinal vehicle motion control subtasks of the DDT with the expectation that the driver completes the object and event detection and response (OEDR) subtask and supervises the driving automation system.

Level 3 – Conditional Driving Automation

The sustained and ODD-specific performance by an ADS of the entire DDT, with the expectation that the human driver will be ready to respond to a request to intervene when issued by the ADS.

Level 4 – High Driving Automation

Sustained and ODD-specific ADS performance of the entire DDT is carried out without any expectation that a user will respond to a request to intervene.

Level 5 – Full Driving Automation

Sustained and unconditional performance by an ADS of the entire DDT without any expectation that a user will respond to a request to intervene. Please note that this performance, since it has no conditions to function, is not ODD-specific.

As you can see, the degree of automation in these mutually exclusive levels increases on a gradient as the levels increase, with Level 0 featuring absolutely no automation, and Level 5 practically sharing similarities with the autonomous systems of science fiction. Notably, the levels are bunched into two overarching groups, with the driver performing part or all of the DDT (Levels 0, 1, and 2) and the ADS performing the entire DDT while engaged (Levels 3, 4, and 5).

This information is only a fraction of the content contained in SAE J 3016-2018: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles. Anyone in need of the document can acquire it on the ANSI Webstore.

4 thoughts on “SAE Levels of Driving Automation
  1. I would have greatly appreciated it if SAE had taken a crack at defining exactly what criteria needs to be satisfied in order for an auto manufacturer to legally sell a Level 4 or 5 allegedly capable vehicle.

    1. There isn’t any criteria that would allow a Level 4 or 5 vehicle to be sold, as current laws state that a driver must be in control of vehicles at all times. The revisement to the USA laws, allowed for Level 2, provided the driver always kept their hands on the wheel. Level 3 vehicles and above are outlawed in USA, without permit. Permits have been issued to several companies to begin testing with driverless vehicles, provided there is a remote driver that is fully connected to the car and able to take over at any moment. A human is still required to be in the driver seat during these testing phases. This ultimately lead to Uber’s permit getting revoked in several states after accidents occurred. There is no telling if the government will ever permit Level 4 or 5 vehicles on the road, without external controls. Such as tracking, monitoring, diagnostic, infrastructure – they may want to upgrade the roads to communicate with vehicles first, or even have construction zones emit a signal to vehicles. There is a ton to fix, but it is not the SAE’s responsibility to provide the criteria by which a vehicle can be legally sold, that is the government’s job.

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