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Motion sickness on-track testing
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
2008 (English)In: Proceedings of the 43rd UK Conference on Human Response to Vibration, 2008Conference paper, Published paper (Other academic)
Abstract [en]

The present evaluation of motion sickness during on-track tests is based on data collected by the Fast And Comfortable Train (FACT) project at the Nordic field tests 2004.

The method chosen for this analysis was to use linear regression between combinations of the collected motion data during the run and the passengers reported level of nausea. The methods of these analyses are based on earlier similar analyses, but here applied on an extended set of data including: transversal accelerations, rotational accelerations, products between transversal and rotational accelerations and more.

Scientists have tried to find models that can describe motion sickness based on one or more motion quantities. The models of motion sickness are derived either by tests in laboratories or by tests on train. In mathematical statistical evaluations these models may be used as hypotheses to be tested. The present analysis is based on six different hypotheses. The model on vertical acceleration shows the highest correlation to motion sickness on trains with active tilt. It is consistent with increased levels of vertical motions in tilting trains compared with non-tilting ones.

However, correlation is high between vertical acceleration and several other motions, which excludes that vertical acceleration is pointed out as the cause to motion sickness in tilting trains. This is a known problem caused by the rules to design railways and how tilting trains acts today.

Place, publisher, year, edition, pages
2008.
Keyword [en]
Tilting trains, Motion sickness, On-track testing
National Category
Vehicle Engineering
Research subject
Järnvägsgruppen - Gröna tåget
Identifiers
URN: urn:nbn:se:kth:diva-33074OAI: oai:DiVA.org:kth-33074DiVA: diva2:413214
Note
QC 20110428Available from: 2011-04-28 Created: 2011-04-28 Last updated: 2011-05-06Bibliographically 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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