The evaluation of driver’s distraction due to driving assistance use requires the development of methods, which allow measuring the driving performance degradation. This paper aims to describe and discuss the metrics utilized in the Lane Change Test, which is developed to become a standard within the ISO framework.

The LCT consists in driving on a three lane road and performing lane changes according to signs displayed on each side of the road. The main metrics are based on deviation measures between a reference trajectory and the current driver trajectory. Two types of reference trajectories can be calculated following an adaptive or a basic model. The adaptive model calculates a reference trajectory different for each participant, while the basic one utilizes an identical one for all participants.

The differences between the two measures have been investigated through an experiment carried out with thirty participants, performing LCT in single and dual task conditions (using auditory and visual manual tasks).

Qualitative analyses of trajectories show the advantage of the adaptive model which better fits to the diversity of real driver’s behaviour. Data analyses also show divergent results according to the models, especially in terms of correctness of lane changes. A greater number of correct lane changes is obtained with the adaptive model than with the basic one. These differences are mainly induced by trajectories classified as loss of control errors using the basic model due to usual positions in the lanes of the driver (tendency to drive on the right or left part of the lanes), that are considered as correct ones using the adaptive model.

The adaptive model allows a better description of lane change errors due to secondary task demand. Such a method is now used by different laboratories involved in ISO group.