Potential of Driver Physiological Measures for Assessing Non-Urban Highway Geometry

Life is a complex phenomenon, mostly controlled by sympathetic and parasympathetic systems. And it is quite dynamic in response to numerous stimulations getting from a system called, human-vehicle-environmental ensemble. Geometry is one of the fundamental stimulus for a driver driving on a highway. His/her mental workload will be based on the input he/she gets from the above system. A system that provides an optimum workload will be the most efficient one. This study explored the capability of different physiological measures to assess the quality of geometric design of non-urban highways. Heart rate, galvanic skin resistance and rate of eye blinking and their variance from base condition were the candidate measures under consideration. Radius of curve, length of curve, length of tangent section, superelevation at curves, degree of curvature, deflection angle and minimum available sight distance at curves were the geometric variables considered. The study included driving experiments done on 114 horizontal curves of gradient less than 2 percentage, each curve being driven over by 30 car drivers. The subjects were equipped with sensors for collecting physiological measures and continuous logging of the data along with geometric coordinates made the database for study. The study revealed the relationship between significant geometric variables and workload measures. The study will be a contribution in the field of road safety auditing, planning and designing of non-urban highways.