Motion sickness on tilting trains

Abstract

Trains that tilt on curves can go faster, but passengers complain of motion sickness. We studied the control signals and tilts to determine why this occurs and how to maintain speed while eliminating motion sickness. Accelerometers and gyros monitored train and passenger yaw and roll, and a survey evaluated motion sickness. The experimental train had 3 control configurations: an untilted mode, a reactive mode that detected curves from sensors on the front wheel set, and a predictive mode that determined curves from the train's position on the tracks. No motion sickness was induced in the untilted mode, but the train ran 21% slower than when it tilted 8° in either the reactive or predictive modes (113 vs. 137 km/h). Roll velocities rose and fell faster in the predictive than the reactive mode when entering and leaving turns (0.4 vs. 0.8 s for a 4°/s roll tilt, P<0.001). Concurrently, motion sickness was greater (P<0.001) in the reactive mode. We conclude that the slower rise in roll velocity during yaw rotations on entering and leaving curves had induced the motion sickness. Adequate synchronization of roll tilt with yaw velocity on curves will reduce motion sickness and improve passenger comfort on tilting trains.

Figure 1.

A) Train (SBB-RABDe 500), similar to the train that was used in the experiments between Winterthur and Gossau, Switzerland. B) Typical tilt of the train on a curve. Note the cant of the tracks, which also helped reduce the tilt of the GIA vector relative to the car and passengers. (From Schweizerische Bundesbahnen) C) Tilt of a wagon car from an intercity tilting train by mechanisms on the bogies. (From Swiss Tilting Trains Modernisation Programme, Railway-Technology, June 20, 2010, p. 3; http://www.railway-technology.com/projects/sbb/).

Figure 2.

Roll velocity (A) and yaw velocity (B) recorded in a typical portion of the track between Winterthur and Gossau from sensors fixed to the train. There were 10 turns, which produced 20 changes in roll velocity in 200 s. The train was in a reactive mode in these recordings. A) Dashed vertical lines and horizontal arrows show 2 typical rising and falling roll velocities that took 2.7 and 4.5 s. B) These roll velocities were associated with sustained increases in yaw velocity of 4°/s. Abscissa is 200 s; ordinates range from −10 to +10°/s.

Figure 3.

Top and third blue traces: yaw and roll angular velocities from sensors on the head of a passenger. Train was making 8° tilts in the reactive mode. Second and fourth blue traces: roll and yaw velocities from sensors on the car. Red lines in top and third traces are train roll and pitch (second and fourth traces), drawn over the recordings of head roll and yaw. Despite many adventitious head movements, the passenger experienced the same yaw and roll velocities as the train. Bottom trace: uncompensated shifts in the GIA relative to the train vertical. Time base (abscissa) is 300 s; ordinates range from −10 to +10°/s or from −10 to +10° (bottom trace).

Figure 4.

Control signals (top and second traces), lateral accelerations (third and fifth traces), and roll velocities (fourth and bottom traces) recorded with the train in the reactive mode (top, third, and fourth traces) and the predictive mode (second, fifth, and bottom traces). Upward arrow in the reactive roll velocity (fourth trace) has oscillations that were not present in the predictive roll velocity. Calibrations of the signals are at left and right. Time base is in seconds and is shown at bottom.

Figure 5.

Car roll velocity (top and third traces) and car linear accelerations (second and fourth traces) for the reactive mode (top and second traces) and predictive mode (third and bottom traces) during the onset of 5 curves. Same curves are represented in the top and second as in the third and bottom traces. Calibrations are at right; time base is at bottom.

Figure 6.

Comparison of head (A, C) and train (B, D) roll velocities during 30 turns on the rails between Winterthur and Gossau with the train in the reactive mode (A, B) and in the predictive mode (C, D). Data in A, B and C, D are from the same segments of track. Four thin vertical lines show the onset and end of train roll in the predictive mode in D. Note the faster rise and fall in train velocity in the predictive mode (D). Lines are projected vertically to demonstrate that roll velocity rose and fell more slowly in the reactive mode (B). Head velocity (A, C) mirrored the differences in train roll velocity in the two modes. Vertical bars at right are calibrations for the train and head velocities. Head roll velocities (A, C) were larger than train roll velocities (B, D). Horizontal bar in D is the time base calibration (1 s) for all of the traces.

Figure 7.

Passenger questionnaire (English translation of original questionnaire in German). Scale was adapted from the Modified Pensacola Scale (Lyne, ref. 30).

Figure 8.

A) Increase in nausea scores after 30-min rides with the train in various configurations. B) Relative comfort of train rides in 10-min segments with the train in various configurations. Light shaded bars indicate scores after 10 min; medium shaded bars, after 20 min; solid bars, after 30 min.