Time Headway (THW)#
Description#
The THW metric calculates the time until actor \(A_1\) reaches the position of a lead vehicle \(A_2\) [Jansson2005] [Junietz2018a].
Analogously to THW, one can define the Headway (HW) metric [Jansson2005] simply as the distance to a lead vehicle, i.e.
Properties#
Run-time capability#
Yes
Target values#
The THW, and HW in one example, are used by regulatory bodies in several countries to express driving recommendations and as a threshold for fines [Junietz2018a].
Country |
Recommended |
Threshold for fines |
---|---|---|
Germany |
1.8 s |
0.9 s |
Sweden |
3 s |
1 s |
Austria |
2 s |
0.4 s |
Subject type#
Road vehicles (automated and human)
Scenario type#
Car following scenarios
Inputs#
Static/dynamic objects and their state (pose, shape, etc.) at time t
Output scale#
\((0,\infty]\), time (s), ratio scale
Reliability#
Medium, comparable to HW with additional consideration of velocity
Validity#
Medium, comparable to HW with additional consideration of velocity
Sensitivity#
High, indicated by its use in legislation [Junietz2018a], also considers velocity compared to HW
Specificity#
Low, as comparable to HW, but additional consideration of velocity
Prediction model#
Time window#
Unbound, but usefulness depends on DMM
Time mode#
Linear time