Autonomous vehicles: Lexicon

There are several terms used to describe how automation and control will be incorporated into vehicles in the future. Several modifiers are used interchangeably in the press and literature:

• automated
• autonomous
• connected
• connected and automated
• connected and autonomous
• driverless
• self-driving

In most cases the degree of automation and control is ambiguous, which is acceptable in advertising and news but not precise enough for transport planning and modeling. The SAE automation levels (opens new window) specifies the degree of both levels. They are arguably the most widely-used definition definition of them, making it suitable for modeling purposes as well. We can define an autonomous vehicle (AV) as one that is both connected and automated. Moreover, we assume an AV is fully automated, corresponding to SAE level 5, unless stated otherwise. A conventional vehicle is one that still requires some level of driver attention and control, which corresponds to SAE levels 0 through 4.

All vehicles, whether conventional or autonomous, can be further classified by its type of ownership or utilization:

• A privately owned vehicle
• A fractionally-owned private vehicle (e.g., co-owned or jointly leased by an extended family living in close proximity of one another)
• An AV leased on a short or long-term basis
• A shared AV (e.g., use of Lyft, Uber, or similar mobility service to fill auto travel needs)

Households and businesses can "mix and match" these AVs in order to meet their mobility needs. An auto-dependent household with two workers might elect to have one conventional auto instead of two, with a shared AV being a cost-effective second vehicle.