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On-track test of strategies for less motion sickness on tilting trains.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.ORCID iD: 0000-0002-2571-4662
(English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159Article in journal (Other academic) Submitted
Abstract [en]

Carbody tilting is today a mature and inexpensive technology that permits higher speeds in horizontal curves, thus shortening travel time. However, tilting trains run a greater risk of causing motion sickness than non-tilting ones. It is likely that the difference in motions between the two train types contributes to the observed difference in risk of motion sickness. Decreasing the risk of motion sickness has until now been equal to increasing the discomfort related to quasi-static lateral acceleration. But, there is a difference in time perception between discomfort caused by quasi-static quantities and motion sickness, which opens up for new solutions. One proposed strategy is to let the local track conditions influence the tilt and give each curve its own optimized tilt angle. This is made possible by new tilt algorithms, storing track data and using a positioning system to select the appropriate data. On-track tests involving more than 100 test subjects onboard a tilting train have been performed to evaluate the effectiveness of the new tilt algorithms and the different requirements on quasi-static lateral acceleration and lateral jerk. The evaluation shows that the rms values important for motion sickness can be influenced without changing the requirements on quasi-static lateral acceleration and lateral jerk. The evaluation also shows that reduced quantities related to motion sickness lead to a reduction in experienced motion sickness. However, this relation seems to be valid in a certain range as the test case with the largest decrease in tilt gave a greater risk of motion sickness than the two test cases with less reduction in tilt. This non-linear relation has also been observed by other researchers in laboratory tests.

Keyword [en]
tilting trains, active tilt, motion sickness, ride comfort, on-track test
National Category
Vehicle Engineering
Research subject
Järnvägsgruppen - Gröna tåget
Identifiers
URN: urn:nbn:se:kth:diva-33076OAI: oai:DiVA.org:kth-33076DiVA: diva2:413219
Note
QS 2011Available from: 2011-04-28 Created: 2011-04-28 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Tilting trains: Enhanced benefits and strategies for less motion sickness
Open this publication in new window or tab >>Tilting trains: Enhanced benefits and strategies for less motion sickness
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Carbody tilting is today a mature and inexpensive technology that allows higher train speeds in horizontal curves, thus shortening travel time. This doctoral thesis considers several subjects important for improving the competitiveness of tilting trains compared to non-tilting ones. A technology review is provided as an introduction to tilting trains and the thesis then focuses on enhancing the benefits and strategies for less motion sickness.

A tilting train may run about 15% faster in curves than a non-tilting one but the corresponding simulated running time benefit on two Swedish lines is about 10%. The main reason for the difference is that speeds are set on other grounds than cant deficiency at straight track, stations, bridges, etc. The possibility to further enhance tilting trains’ running speed is studied under identified speed limitations due to vehicle-track interaction such as crosswind requirements at high speed curving. About 9% running time may be gained on the Stockholm–Gothenburg (457 km) mainline in Sweden if cant deficiency, top speed, and tractive performance are improved compared with existing tilting trains. Non-tilting high-speed trains are not an option on this line due to the large number of 1,000 m curves.

Tilting trains run a greater risk of causing motion sickness than non-tilting trains. Roll velocity and vertical acceleration are the two motion components that show the largest increase, but the amplitudes are lower than those used in laboratory tests that caused motion sickness. Scientists have tried to find models that can describe motion sickness based on one or more motion quantities. The vertical acceleration model shows the highest correlation to motion sickness on trains with active tilt. However, vertical acceleration has a strong correlation to several other motions, which precludes vertical acceleration being pointed out as the principal cause of motion sickness in tilting trains.

Further enhanced speeds tend to increase carbody motions even more, which may result in a higher risk of motion sickness. However, means to counteract the increased risk of motion sickness are identified in the present work that can be combined for best effect. Improved tilt control can prevent unnecessary fluctuations in motion sickness related quantities perceived by the passengers. The improved tilt control can also manage the new proposed tilt algorithms for less risk of motion sickness, which constitute one of the main achievements in the present study. Local speed restrictions are another means of avoiding increased peak levels of motion sickness when increasing the overall speed.

The improved tilt control and the proposed tilt algorithms have proven to be effective in on-track tests involving more than 100 test subjects. The new tilt algorithms gave carbody motions closer to non-tilting trains. Rather unexpectedly, however, the test case with the largest decrease in tilt gave a greater risk of motion sickness than the two test cases with less reduction in tilt. It is likely that even better results can be achieved by further optimization of the tilt algorithms; the non-linear relation between motions and motion sickness is of particular interest for further study.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. vi, 36 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2011:26
Keyword
tilting trains, running time, ride comfort, motion sickness, tilt control
National Category
Vehicle Engineering
Research subject
Järnvägsgruppen - Gröna tåget
Identifiers
urn:nbn:se:kth:diva-33077 (URN)978-91-7415-948-6 (ISBN)
Public defence
2011-05-19, D3, Lindstedtsvägen 5, KTH, Stockholm, 09:30 (English)
Opponent
Supervisors
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note
QC 20110429Available from: 2011-04-29 Created: 2011-04-28 Last updated: 2012-06-12Bibliographically approved

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