Abstract
Variation in systolic blood pressure was an effective parameter in the evaluation of geometrical design of forest roads from the viewpoint of driver's psychological and physiological response. The authors attempted to evaluate geometrical design of forest roads by variation in pulse pressure (difference between systolic blood pressure and diastolic blood pressure) for driver's psychological response on the basis of variation in systolic blood pressure. As a result, the variation coefficient of the pulse pressure increased with the increase in the speed of vehicles. This increasing tendency especially in case of small curve radius, became more significant because of muliplicative effect between the speed of vehicles and radius size. The variation coefficient of the pulse pressure when the vehicle drove around the right side of mountain was found to be higher than when the vehicle did on the left side of mountain. Furthermore, the variation coefficient of pulse pressure increased with the decrease in curve radius and the increase in the speed of vehicles. When the radius of curve was less than about 20m, an apparent variation in pulse pressure was observed, which resulted in a big psychological load on the driver. Pulse pressure reflected sensitively on psychological pressure. Thus the geometrical design of forest roads under the condition of greatly psychological load on a driver was accurately evaluated using the variation in pulse pressure as an additional measure, when variation in systolic blood pressure was used as the main parameter of an evaluation.
