Time To Brake (TTB)#

Description#

Please refer to the TTM.

Properties#

Run-time capability#

Yes

Target values#

0.4 s [Tamke2011] (selection of a minimal risk maneuver), 1 s [Junietz2018a] [Huber2020] (threshold for critical)

Subject type#

Optimal for road vehicles (automated and human), sub-optimal for VRUs

Scenario type#

Overlapping predicted trajectories for a significant time span in the scenario

Inputs#

Static/dynamic objects and their state (pose, shape, etc.) at time t, MM for maneuver ‘brake’

Output scale#

\(\{-\infty\} \cup [0, \infty]\), time (s), ratio scale

Reliability#

High, under the assumption that collisions can be reliably predicted

Validity#

High for two-actor scenes, medium for more actors when TTB is evaluated under a fixed perspective, but can be increased by aggregating over all actors as at least for one of them, the TTB will be valid

Sensitivity#

High, but depends on the DMM: if no collisions are predicted for critical scenarios, sensitivity is reduced

Specificity#

High for humans, as braking is a key choice in human reaction [Adams1994]; medium for AVs as non-braking maneuvers can often avoid a critical situation, even if TTB \(\leq0\) [Adams1994]