NHTSA Lays Out Groundrules For Autonomous Vehicles

June 7, 2013

You know it, we know it, and apparently the National Highway Traffic Safety Administration knows it, too: autonomous vehicles are a-comin'. That's why NHTSA has crafted a set of guidelines (PDF) for states that wish to follow in the footsteps of California, Florida, and Nevada and legalize self-driving cars.

In doing so, NHTSA has also created an interesting system of classification for autonomous vehicles that could prove useful down the line. The system scores vehicles on a scale of 0 to 5, depending on their level of automation:

No-Automation (Level 0): The driver has complete control of the vehicle. No onboard systems can possibly intervene to affect braking, steering, or any other function.

Function-specific Automation (Level 1): Certain functions are designed to assist drivers at particular tasks. As an example, NHTSA cites "pre-charged brakes, where the vehicle automatically assists with braking to enable the driver to regain control of the vehicle or stop faster than possible by acting alone". NHTSA also puts vehicles with electronic stability control in this category, and since ESC is now mandatory on passenger cars in the U.S., that means that all new cars are Level 1 vehicles, at minimum

Combined Function Automation (Level 2): To earn this designation, a vehicle must have at least two automated systems that work together in key situations, but don't allow the driver to cede complete control to the onboard computer. NHTSA cites the example of adaptive cruise control (i.e. automated braking) and lane centering (i.e. automated steering), which can work in unison under certain conditions. Many of today's luxury vehicles meet this standard.  

Limited Self-Driving Automation (Level 3): This is where the well-known Google car falls. By NHTSA's definition, a Level 3 vehicle can handle all driving functions at the driver's discretion. According to the guidelines, in a Level 3 vehicle, "The driver is expected to be available for occasional control, but with sufficiently comfortable transition time".

Full Self-Driving Automation (Level 4): Level 4 vehicles are fully automated. The driver (or rather, "driver") indicates where she'd like to go, and the car takes care of the rest. No one in the vehicle is expected to be able to take control of the vehicle at any time. We haven't seen this degree of automation yet, though the most advanced self-driving vehicles appear capable of it.

As our colleagues at Motor Authority have pointed out, NHTSA is wary of sanctioning Level 3 and 4 vehicles for consumer use at this point. In fact, the guidelines say very clearly that "NHTSA has considerable concerns...about detailed state regulation on safety of self-driving vehicles, and does not recommend at this time that states permit operation of self-driving vehicles for purposes other than testing." 

In such testing situations, NHTSA's recommendations include:

  • that on-road testing of autonomous vehicles minimizes the risk to other drivers.
  • that tests are limited to "roadway, traffic, and environmental conditions suitable for the capabilities of the tested self-driving vehicles". (This means you, Red Bull marketing department.)
  • that testing data is recorded and shared with the appropriate agencies -- especially when things go wrong.
  • that a vehicle's process of switching from automated driving to human-controlled driving is smooth and safe.
  • that none of the autonomous technologies used on self-driving cars interfere with or override federally mandated equipment.

The guidelines themselves don't carry the weight of law, but they appear fairly reasonable and common-sense.

The classification system may be even more useful, as we begin the long, slow transition from Level 0 and 1 cars to Level 3s and 4s. Categorizing vehicles and tailoring regulations for each leveI? It's the sort of thing bureaucrats dream about.


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