Reduced travel times are a major issue for railway companies. Reductions can be achieved by building new lines with a high standard of track alignment or by using tilting train on existing lines. However, for some passengers the tilt motions may provoke motion sickness and discomfort. Modelling and prediction of motion sickness and nausea from vertical and horizontal accelerations have been investigated and developed through the combined efforts of may researchers. Vertical accelerations have been reported to have a strong influence on nausea, but less is known about the influence of rolle motion. For tilting trains, where the tilt motion is used for reducing the lateral acceleration perceived by the passenger and thus improving comfort, it is likely that the primary cause of nausea is tilt motion in combination with low-frequency vertical and lateral acceleration. In 1995, field tests were conducted with three conditions in a tilting train and in 1998 additional tests with a total of seven combinations of horizontal and roll motions were conducted in a moving base simulator at the VTI. Test subjects, mostly students, rated their illness and nausea according to a five-degree scale together with comfort, ability to work and read, etc. Evaluated variables were percentage of test subjects with motion sickness symptoms (SMSI) and nausea and illness ratins (NR and IR). Additional field tests were performed in Norway during November 1999. In the train experiments, SMSI was mainly correlated with the motion doses from roll accelerations. In the simulator experiments, vertical acceleration was most highly correlated with NR, but horizontal (lateral) acceleration together with roll acceleration were significantly better explaining variables. Net dose models with leakage of accumulated doses are a good alternative when motion environments change during the journey. Good regression models have been found with horizontal and roll acceleration for explaining nausea ratings in the simulator. However, roll angles and horizontal accelerations are quite closely correlated in tilting trains, and roll motion doses are therefore the primary explaining variable regarding nausea in such trains. Models that leakage into consideration are required in order to explain nausea ratings on routes with both curved and less curved sections. Optimisation of tilt motion must take into account both the risk of nausea and the risk of comfort disturbances caused by large perceived lateral accelerations, as well as the distribution of curves along the route. Also curve geometry and transition curve lengths interact significantly and must be taken into account, while preventing discomfort for passengers. Further research needs to be conducted on the basis of these aspects. (A)
Abstract