Low frequency vertical accelerations can provoke motion sickness and nausea in ships and aeroplanes and probably, combined with horizontal (lateral) acceleration, also in cars and buses. However, tilting trains and banking aeroplanes generate roll motions, which may provoke motion sickness in sensitive humans. Some seventy healthy volunteers were employed. They were tested in a high speed tilting train (X2000) with three different tilt control strategies during three days. Different ratios of tilt compensation were used. The test rides lasted about three hours. Four times per test the subjects answered a questionnaire concerning comfort and discomfort. The train motion environment was monitored and recorded during the test rides. Motion doses, for prediction of motion sickness, were calculated from vertical and also from lateral and roll accelerations for the test track. The conditions with 55 per cent ratio of tilt compensation instead of the normal 70 per cent, reduced the discomfort from about 15 per cent to about 8-10 per cent. No reduction of subjective ride comfort or working ability was recorded in these conditions with 55 per cent compensation. Discomfort correlates fairly well with motion dose of roll acceleration but not with vertical or lateral motion doses. This means that optimised tilt control system should reduce the motion dose from roll acceleration in order to minimise provocation of motion sickness. On the other hand, too small compensation ratios will cause discomfort by too large lateral accelerations. (A)
Abstract