Determinants of Motion Sickness in Tilting Trains: Coriolis/Cross-Coupling Stimuli and Tilt Delay

Abstract

Faster trains require tilting of the cars to counterbalance the centrifugal forces during curves. Motion sensitive passengers, however, complain of discomfort and overt motion sickness. A recent study comparing different control systems in a tilting train, suggested that the delay of car tilts relative to the curve of the track contributes to motion sickness. Other aspects of the motion stimuli, like the lateral accelerations and the car jitters, differed between the tested conditions and prevented a final conclusion on the role of tilt delay. Nineteen subjects were tested on a motorized 3D turntable that simulated the roll tilts during yaw rotations experienced on a tilting train, isolating them from other motion components. Each session was composed of two consecutive series of 12 ideal curves that were defined on the bases of recordings during an actual train ride. The simulated car tilts started either at the beginning of the curve acceleration phase (no-delay condition) or with 3 s of delay (delay condition). Motion sickness was self-assessed by each subject at the end of each series using an analog motion sickness scale. All subjects were tested in both conditions. Significant increases of motion sickness occurred after the first sequence of 12 curves in the delay condition, but not in the no-delay condition. This increase correlated with the sensitivity of motion sickness, which was self-assessed by each subject before the experiment. The second sequence of curve did not lead to a significant further increase of motion sickness in any condition. Our results demonstrate that, even if the speed and amplitude are as low as those experienced on tilting trains, a series of roll tilts with a delay relative to the horizontal rotations, isolated from other motion stimuli occurring during a travel, generate Coriolis/cross-coupling stimulations sufficient to rapidly induce motion sickness in sensitive individuals. The strength and the rapid onset of the motion sickness reported confirm that, even if the angular velocity involved are low, the Coriolis/cross-coupling resulting from the delay is a major factor in causing sickness that can be resolved by improving the tilt timing relative to the horizontal rotation originating from the curve.

Optimal speed profile on a given road for motion sickness reduction

“…The proposed countermeasures for MS in vehicles are mostly qualitative: suggest to maximise the visual field of the occupants and to avoid rearward orientation of seats; Wada et al (2010) suggest to lean inward the head when approaching a turn to keep the head more aligned with the gravitoinertial acceleration; indication about future vehicle motion can be helpful as per Kuiper et al (2020), however, implementing head-up displays showing the planned trajectory as per Feenstra et al (2011), might be infeasible for multiseated cars. A more quantitative approach has been proposed by Sugiura et al (2019) using tilting seats to be more consistent compared to the head tilting strategy; however, similar approaches in tilting trains gave unclear results as per Cohen et al (2011); Bertolini et al (2017).…”

“…The research interest is very strong because such frequencies are characteristic for all transportation systems, so every kind of transportation system is affected by different versions of the same issue: sea-sickness was the first as per Irwin (1881), nevertheless, further studies have continued in more recent years and lead to the fundamental experimental studies of O' Hanlon and McCauley (1973); Lawther and Griffin (1986); airsickness is also studied as per Turner et al (2000); space sickness is another variant of the same issue in a slightly different context and an example of the scientific interest is in Oman (1987); trains are studied by Bertolini et al (2017); Braccesi et al (2013); road vehicles are widely studied as in Wada et al (2010); Sugiura et al (2019); Bronstein et al (2020). Simulators are also widely studied because in such contexts the visualvestibular conflict can be quite extreme due to vection; therefore several scientists as Kennedy et al (1993); Ohyama et al (2007); Zużewicz et al (2011) studied such topics.…”

The neural basis of motion sickness

“…This postulate was strongly supported by studies that featured movement in roll (Bertolini and Straumann 2016;Bles 1998;Cohen et al 2011;Donohew and Griffin 2004;Joseph and Griffin 2008), as well as by studies using off-vertical axis rotation (OVAR) (Dai et al 2010;Guedry 1976). In the latter, the amount of motion sickness during OVAR was linearly related to the deviation of the axis of rotation from the spatial vertical, the dependence of motion of horizontal linear acceleration with roll (Donohew and Griffin 2004;Joseph and Griffin 2008), and by the occurrence of motion sickness on tilting trains when there was coincidence of lateral linear acceleration and roll (Bertolini et al 2017;Cohen et al 2011). Thus, roll was an essential factor in generating the nausea.…”