Automated Driving Definitions
SAE J3016 authoritatively defines many terms related to automated driving, including the levels of driving automation. While those who are serious about this field should read the actual document, the following offers a gloss on points of public interest. For additional context, see How Reporters Can Evaluate Automated Driving Announcements.
Your role in driving automation
Driving involves paying attention to the vehicle, the road, and the environment so that you can steer, brake, and accelerate as needed. If you're expected to pay attention, you're still driving -- even when a vehicle feature is assisting you with steering, braking, and/or accelerating. (Driving has a broader meaning in SAE J3016 and may also have a broader meaning in law.)
Types of trips
A. You must drive for the entire trip
B. You will need to drive if prompted in order to maintain safety
C. You will need to drive if prompted in order to reach your destination
D. You will not need to drive for any reason, but you may drive if you want
E. You will not need to drive for any reason, and you may not drive
Types of vehicles
A. Vehicles you can drive
B. Vehicles you can't drive
Types of vehicle features
These are the levels of driving automation. They describe features in vehicles rather than the vehicles themselves. This is because a vehicle's feature or features may not always be engaged or even available.
The operational design domain (ODD) describes when and where a feature is specifically designed to function. For example, one feature may be be designed for freeway traffic jams, while another may be designed for a particular neighborhood in good weather.
By describing a feature's level of automation and operational design domain, the feature's developer makes a promise to the public about that feature's capabilities.
Assisted driving features
L0: You're driving
L1: You're driving, but you're assisted with either steering or speed
L2: You're driving, but you're assisted with both steering and speed
Automated driving features
L3: You're not driving, but you will need to drive if prompted in order to maintain safety
L4: You're not driving, but either
a) you will need to drive if prompted in order to reach your destination (in a vehicle you can drive) or
b) you will not be able to reach every destination (in a vehicle you can't drive)
L5: You're not driving, and you can reach any destination