(Source: AndSus / stock.adobe.com)
Following in the tire tracks of Honda’s 2021 launch of the Level 3-equipped Legend in Japan, Mercedes-Benz introduced SAE Level 3 autonomy to the US with the Drive Pilot option on the 2024 S-Class and EQS Sedan. These vehicles are not only at the cutting edge of automotive technology, but they also push the boundaries of regulatory frameworks with an unprecedented handoff of responsibility from the driver to the vehicle. As ADAS technology matures, so too must the legal and regulatory fields as we rethink the role of the driver.
Level 3 represents a significant leap both in terms of technology and liability. Referring to the SAE table in Figure 1, Level 3 is the first level at which there are scenarios where the person in the driver’s seat is not actually the driver. If you get into an accident while Level 3 features are active, the automaker takes liability. The vehicle becomes “the driver.”
Figure 1: SAE Levels of Driving Automation (Source: SAE International)
The gap between Levels 2 and 3 has as much to do with legality as it does with technology. Both Level 2 and 3 vehicles can maintain their speed behind another car and stay in their lane. The difference is if you get into an accident while driving your Level 2 vehicle, you are held liable. If you get into an accident while Level 3 features are active, the automaker takes liability. This important distinction means that in the eyes of the law, the driver is not actually “driving” the car under Level 3 automation.
Herein lies the most difficult challenge in moving from Level 2 to Level 3: the human factor. A study from the German Insurers Accident Research placed drivers in a driving simulator emulating a Level 3 vehicle requesting a driver takeover while the automated features were active.[1] The results showed that drivers fixated on a particularly engaging non-driving task—playing Tetris on the vehicle’s infotainment console—took five seconds longer than engaged drivers to get their feet on the pedals, hands on the wheel, and eyes on the road, speedometer, and rearview mirror.
Five seconds may not seem like a long time, but a vehicle at highway speeds of 120km/h will travel 165 meters in that time. Automakers must weigh the risks and rewards of Level 3—relying on a distracted person to quickly switch tasks creates a major vulnerability in the system. Test drivers fell asleep at the wheel during early tests of Ford’s self-driving cars.[2] Mercedes’ Drive Pilot mitigates the human factor by putting some boundaries on what the driver can do when self-driving is active. Cameras on the driver make sure they are awake and facing the road, and sensors detect if the seat reclines. Mercedes clearly learned from Ford’s sleepy test drivers.
As drivers, we sometimes make judgment calls on where and how to drive when lane markings are worn away, or weather conditions inhibit visibility. Construction zones may use temporary lane markers to create new traffic patterns. Emergency responders sometimes direct traffic using hand signals, overriding road signs and traffic lights. Sometimes, we might need to avoid a pothole or debris in the road by using an adjacent lane.
The engineering challenge for autonomous vehicles is not in getting them to cruise on the road. The real challenge is preparing the vehicles to navigate unique situations that they have not specifically been trained for. This is where machine learning becomes critical. Scenarios recorded by vehicles already on the roads give automakers plenty of material to refine their algorithms. Automakers can then complete the feedback loop by pushing over-the-air updates to their fleets so the vehicles can learn from each other’s experiences.
Level 3 vehicles are just as complex from a legal perspective as they are from a technological perspective (Figure 2). The handoff of liability back and forth between the driver and the vehicle is unprecedented in the US. Automotive engineers should understand the regulatory landscape and standards that govern their work.
Figure 2: Advances in autonomous capabilities require advances in the law (Source: Studio Romantic / stock.adobe.com)
Autonomous vehicles create interesting legal edge cases. For example, Tesla offers an option called Smart Summon, where the car can drive itself to the user from its parking spot. In the eyes of the law, the car’s user is still liable for any fender bender the car gets into despite not actually being in the car.
Understanding driver and vehicle responsibilities is also important for Level 2-enabled vehicles, where drivers may become complacent and act as if they’re in a Level 3 or 4 vehicle. Automakers must make the limitations of their autonomous features clear to drivers, and drivers must understand that most of the time, they are still ultimately in control.
Level 3 vehicles are an important milestone on the journey to making roads safer and more efficient. While this cutting-edge technology only serves limited areas for now, Level 1 and 2 ADAS features are becoming more prevalent globally. Smarter vehicles that take a more active role on the road push both technological and legal boundaries. The road to Level 4 consumer vehicles will involve refining what we learn from Level 3 and commercial Level 4 vehicles, as well as developing a robust regulatory framework.
[1]Zhuoqun Dai, Yang Li, Max Caspar Sundermeier, Tobias Grabe, and Roland Lachmayer. “Lidars for vehicles: from the requirements to the technical evaluation,” 2021, https://www.repo.uni-hannover.de/bitstream/handle/123456789/11439/Dai2021_Lidars_for_vehicles.pdf?sequence=4..
[2]Michael Cantu, “Ford Engineers Can’t Stay Awake in Driverless Cars,” MotorTrend, February 20, 2017, https://www.motortrend.com/news/ford-engineers-cant-stay-awake-in-driverless-cars/.
Matt Campbell is a technical storyteller at Mouser Electronics. While earning his degree in electrical engineering, Matt realized he was better with words than with calculus, so he has spent his career exploring the stories behind cutting-edge technology. Outside the office he enjoys concerts, getting off the grid, collecting old things, and photographing sunsets.
