First, the changing rate of a heart rate increases as stress intensifies. The following data reveals the 50 percentiles of 'Comfortable', 'Nervous' and 'Very nervous': 28.14%, 30.43%, and 38.78% respectively. Second, the three categories have different statistical distributions, amongst which the 'Comfortable' category is normally distributed. Third, stress is a complicated concept. Of course, the word 'concept' does not mean that it cannot be understood in a concrete way. As shown in previous illustrations, however, a drivers' perception of stress and their resistance to stimuli heavily influence reported stress levels. Other influencing factors include road environment, violation of drivers' expectancy, incidence, geometry, driving experience and physique, etc. Last but not least, the standard deviation increases as one's stress level intensifies. This follows the conclusion that people's eccentricity, which usually posts a hazard to safety, takes hold as stimuli surge. Road departments should put a cap on the stimuli or information that drivers are exposed to, since it is impossible to build a facility accommodating various traits of road users. A problem for further study is the micro-classification of stress levels, which partially causes the medium category overlapping with the other two categories and having the largest range. In future studies, a less complicated stress classification is in order. Besides, a sample size of the 'Very nervous' category is far from yielding satisfactory and precise statistics. Therefore, a great room has been left to investigate drivers' response in an extreme frustrating scenario. For the covering abstract see ITRD E138091. This paper is available from http://www.ictct.org/workshops/07-Beijing/46YiyiWang176183.pdf.
Samenvatting