Method to Evaluate Driver's Workload in Real Road Context

Innovative technology implemented in the vehicle can induce improvement in road safety, as long as its acceptability and its adequacy are checked, taking into account the diversified driver's population needs and functional abilities through a Human Centred Design process. Relevant methodology has to be developed in this purpose. Evaluation of the driver's mental workload is an important parameter, complementary to objective ones such as control of the vehicle and driver's visual strategies. This paper reports on 3 real road experiments run for the assessment of mobile phone and guidance/navigation systems usability. Evaluation has been based upon a method of Subjective evaluation of the driver's mental workload: the Driving Activity Load Index (DALI). Use of the DALI allowed identifying which aspects of the system had to be improved, for an improved acceptability and usability by the drivers.