6 Levels of Autonomous Driving

Whether you accept it or not, autonomous vehicles will eventually arrive. These vehicles will bring a host of safety, legal, and technical problems. With two months left in 2023, this year has already seen 126 autonomous vehicle crashes in California.

The responsibility for these crashes depends on the level of automation. Thus, sorting out many of the issues surrounding automated vehicles first requires an understanding of how they work and the roles of the occupants and the autonomous vehicle.

Classifying Autonomous Vehicles

The number of crashes of human-controlled vehicles dwarfs the 126 autonomous vehicle crashes through the first ten months of 2023. California had nearly 160,000 traffic crashes that caused injury or death in 2022. If 2023’s crash number falls anywhere near 2022’s number, the state could have 1,000 crashes of human-controlled vehicles for every crash of an autonomous vehicle.

However, treating autonomous vehicles equally produces a misleading picture. The Society of Automotive Engineers (SAE) has adopted a six-tier system for categorizing autonomous vehicle technologies. The National Highway Transportation Safety Administration (NHTSA) and other transportation experts have accepted this system as the standard for classifying these vehicles.

The six levels are numbered zero through five. Zero represents the lowest level of automation while five represents full automation. The classes defined by the SAE include the following:

Level Zero

You might already have a level-zero vehicle without considering it autonomous. Level-zero vehicles have driver assistance technologies without replacing the driver. Specifically, the driver performs all driving and all monitoring tasks in the vehicle.

However, these vehicles can assist the driver. Some examples of level-zero driver assistance technologies include:

  • Blind spot warnings
  • Frontal collision warnings
  • Lane departure warnings

These systems use sensors to detect potentially dangerous maneuvers, such as changing lanes while another vehicle is next to you. The sensors can trigger a warning, but they cannot stop you from colliding with the other vehicle.

Level One

Level-one vehicles have driver assistance technologies that can temporarily control the vehicle, but the driver is otherwise fully responsible for monitoring and controlling the vehicle.

Level-one technologies can control only the speed or direction, but not both. Thus, level-one vehicles may have autonomous acceleration or braking in certain conditions. An example of this system includes a frontal collision avoidance system that automatically brakes to prevent a rear-end collision.

Alternatively, a level-one system can automatically control steering. A lane-centering system is an example of this type of level-one system.

Level Two

Level-two vehicles have autonomous systems that can control speed and direction simultaneously, but only when activated. In other words, after the autonomous system has completed its maneuver, it returns control of the vehicle to the driver. Self-parking cars are examples of level-two vehicles.

Level Three

Level-three vehicles drive you. But they still include manual controls so you can take over. Below this level, you must monitor and drive the vehicle. At level three, you must still monitor the vehicle, but the vehicle drives itself until you intervene. Honda and Mercedes both have level-three vehicles. Tesla, GM, and Ford are pursuing level-three technologies.

Levels zero through three rely on a combination of humans and machines. Safety at these levels comes from the possibility of driver intervention when the automated system goes down. But safety also comes from the possibility that the automated vehicle can help the driver avoid human errors.

Levels Four and Five

Vehicles at levels four and five have the same levels of automation. These vehicles perform all the driving tasks and don’t require any human monitoring. In fact, they include no manual controls for a “driver.” These vehicles only carry passengers.

The difference between levels four and five comes from the area where they operate. Level-four vehicles operate in a limited service area. Level-five vehicles can operate anywhere.

By limiting the service area, a level-four vehicle does not need to recognize unfamiliar environments. Instead, programmers can either train it in its limited environment or use beacons in the service area to guide the vehicle. Examples of level-four systems include test projects in San Francisco and on the Strip in Las Vegas.

Level-five vehicles must have sophisticated artificial intelligence systems to recognize unfamiliar roads. They must also navigate to unknown locations. No autonomous vehicle has reached level five.

The safety of level-four and level-five vehicles comes from the removal of the driver from the equation. Without a driver, you do not have intoxicated driving, distracted driving, and careless driving. But by relying solely on the vehicle, glitches in the software can produce systemic problems across entire models or makes of vehicles.

What Happens After an Autonomous Vehicle Crash?

California requires auto manufacturers to report all autonomous vehicle crashes. These reports serve two purposes. First, the state can monitor crashes and look for patterns. Second, the state releases the crash reports to the public. Consumers can use these reports to decide which vehicles meet their expectations for safety.

The level of automation determines whether the crash happened due to a driver error or a vehicle glitch. In time, consumers, manufacturers, and regulators will use this information to improve safety for everyone.


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