Figure 2

Hypothetical illustrations of the definition of the potential unsafe driving period. Dark line is the evolution of the observed performances of the driver; light line is the evolution of the performances needed to drive safely; actual shapes are unknown and hypothetical. a) possible typical situation: the increased risk of collision is due to an acute increase of the performances needed to drive safely (point 1), to an acute decrease of actual performances of the driver (point 2), or because the driving performances of the driver with a medical condition become systematically lower than the performances needed to drive safely (unknown position of point 3). b) the self-regulatory strategies delay the entry in the potential unsafe driving period (shift of point 3). c) the self-regulatory strategies avoid the entry in the potential unsafe driving period.