189The Future of Intelligent Transport Systems. http://dx.doi.org/10.1016/B978-0-12-818281-9.00017-6
Copyright © 2020 Elsevier Inc. All rights reserved.
Chapter 17
Autonomous driving levels
and enablers
17.1 Autonomous driving levels
The advantages of the use of systems that automatically control the main driv-
ing controls of the vehicle such as steering, brakes, and throttle have been early
understood by researchers and transportation experts (Hahn, 1996). The ability
of the autonomous vehicles to brake on traffic allows them to conserve fuel
more efficiently. Effective crash avoidance technologies assist in reducing traf-
fic congestions and cruise control systems reduce greenhouse gas emissions.
Finally, interconnected vehicles that exchange information and data [vehicle
to vehicle (V2V) communication] and communicate with the highway infra-
structure [vehicle to infrastructure (V2I) communication] aim to increase travel
safety and reduce travel times and congestions.
When referring to autonomous vehicles, we not necessarily refer to vehicles
that are 100% autonomous and can behave equally well in all conditions. There
are several studies in the last decade that define the autonomous driving levels.
The early study of Gasser & Westhoff (2012) defined five vehicle automa-
tion degrees from driver only to full automation and two more dimensions that
define at what level the driver interacts with the vehicle automation, when the
automation can be applied (e.g., the speed range and the road conditions that
must hold) and for how long. The automation levels are as follows:
• In the “Driver Only” level the responsibility of the manual driving task
resides solely to the driver.
• In the “Driver Assistance” level, the driver has permanent control over the
vehicle in space and time, but the vehicle automation is active and provides
assistive information, notifications, and alerts.
• In the “Partial Automation” level, the vehicle takes over control. However,
the driver must monitor the system and be ready to take over control at any
time.
• In the “High Automation” level, the vehicle takes over the control again. In
this case, the driver does not have to monitor the system at all times but is
rather notified by the system when there is a need to take-over.