Headway (HW) ============ Description ----------- Please refer to the :doc:`THW`. Properties ---------- Run-time capability ~~~~~~~~~~~~~~~~~~~ Yes Target values ~~~~~~~~~~~~~ 50 m [Junietz2018a]_ (threshold for fines) Subject type ~~~~~~~~~~~~ Road vehicles (automated and human) Scenario type ~~~~~~~~~~~~~ Car following scenarios Inputs ~~~~~~ Positions :math:`p_i` for :math:`i \in \{1, 2\}`, information to determine lead vehicles Output scale ~~~~~~~~~~~~ :math:`[0,\infty)`, meter (m), ratio scale Reliability ~~~~~~~~~~~ Low, as many changes in criticality (e.g. significantly higher speed in a situation) are not reflected by HW Validity ~~~~~~~~ Medium, a small distance to front does not always imply high criticality, but is also a factor present in many accidents Sensitivity ~~~~~~~~~~~ High, as indicated by the use of HW in legislation [Junietz2018a]_, most critical situations do imply small distance to front for at least one involved actors Specificity ~~~~~~~~~~~ Low, as a large distance to front does not always imply low criticality Prediction model ~~~~~~~~~~~~~~~~ Time window ^^^^^^^^^^^ Unbound, but usefulness depends on DMM Time mode ^^^^^^^^^ Linear time