SAE INTERNATIONAL J3016™ SEP2016 Page 6 of 30
For purposes of DDT performance, level 1 encompasses automation of part of the innermost loop (i.e., either lateral vehicle
motion control functionality or longitudinal vehicle motion control functionality and limited OEDR associated with the given
axis of vehicle motion control); level 2 encompasses automation of the innermost loop (lateral and longitudinal vehicle
motion control and limited OEDR associated with vehicle motion control), and levels 3-5 encompass automation of both
inner loops (lateral and longitudinal vehicle motion control and complete OEDR). Note that DDT performance does not
include strategic aspects of driving (e.g., determining whether, when and where to travel).
3.9 [DYNAMIC DRIVING TASK (DDT)] FALLBACK
The response by the user or by an ADS to either perform the DDT or achieve a minimal risk condition after occurrence of a
DDT performance-relevant system failure(s) or upon ODD exit.
NOTE 1: The DDT and the DDT fallback are distinct functions, and the capability to perform one does not necessarily
entail the ability to perform the other. Thus, a level 3 ADS, which is capable of performing the entire DDT within
its operational design domain (ODD), may not be capable of performing the DDT fallback in all situations that
require it and thus will issue a request to intervene to the DDT fallback-ready user when necessary.
NOTE 2: At level 3, an ADS is capable of continuing to perform the DDT for at least several seconds after providing the
fallback-ready user with a request to intervene. The DDT fallback-ready user is then expected to achieve a
minimal risk condition if s/he determines it to be necessary.
NOTE 3: At levels 4 and 5, the ADS must be capable of performing the DDT fallback, as well as achieving a minimal risk
condition. Level 4 and 5 ADS-equipped vehicles that are designed to also accommodate operation by a driver
(whether conventional or remote) may allow a user to perform the DDT fallback if s/he chooses to do so.
However, a level 4 or 5 ADS need not be designed to allow a user to perform DDT fallback and, indeed, may
be designed to disallow it in order to reduce crash risk (see 8.3).
NOTE 4: While a level 4 or 5 ADS is performing the DDT fallback, it may be limited by design in speed and/or range of
lateral and/or longitudinal vehicle motion control (i.e., it may enter so-called “limp-home mode”).
EXAMPLE 1: A level 1 adaptive cruise control (ACC) feature experiences a system failure that causes the feature to stop
performing its intended function. The human driver performs the DDT fallback by resuming performance
of the complete DDT.
EXAMPLE 2: A level 3 ADS feature that performs the entire DDT during traffic jams on freeways is not able to do so when
it encounters a crash scene and therefore issues a request to intervene to the DDT fallback-ready user.
S/he responds by taking over performance of the entire DDT in order to maneuver around the crash scene.
(Note that in this example, a minimal risk condition is not needed or achieved.)
EXAMPLE 3: A level 4 ADS-dedicated vehicle (ADS-DV) that performs the entire DDT within a geo-fenced city center
experiences a DDT performance-relevant system failure. In response, the ADS-DV performs the DDT
fallback by turning on the hazard flashers, maneuvering the vehicle to the road shoulder and parking it,
before automatically summoning emergency assistance. (Note that in this example, the ADS-DV
automatically achieves a minimal risk condition.)
Downloaded from SAE International by Michiaki Sekine, Sunday, October 02, 2016