This chapter considers the use of physiological measures to validate driver monitoring, with special reference to alcohol and drugs, driver vigilance and driver task load. Careful research under controlled conditions is needed, to assess an individual's optimum and deviations from that optimum, with respect to the relationship between physiology and performance. Physiological changes, resulting from the intake of alcohol or other drugs, include effects on heart beat rate and the EEG (electro-encephalogram) power density spectrum. Driving on a road with light traffic can be monotonous, and thus a vigilance task for experienced drivers, resulting in mental underload and making drivers more accident-prone. Underload conditions lead to changes in the EEG spectrum. High-pressure situations, resulting in mental overload, may be a major cause of intersection-related accidents, for example. They can be correlated with heart rate and heart rate variability. The author concludes that combined measurements of a driver's physiology and behaviour have demonstrated the feasibility of developing a monitoring device, using only a limited number of unobtrusive vehicle parameters. However, it is very difficult if not impossible to predict the reduction in casualties from introducing risk-reducing driving aid systems, because there are no valid data from which to estimate the risks of specific traffic behaviours.
Abstract