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Difficulties to Read and Write Under Lateral Vibration Exposure: Contextual Studies Of Train Passengers Ride Comfort
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Many people use the train both as a daily means of transport as well as a working place to carry out activities such as reading or writing. There are, however, several important factors in this environment that will hamper good performance of such activities. Some of the main sources of disturbance, apart form other train passengers, are noise and vibrations generated from the train itself.

Although there are standards available for evaluation of ride comfort in vehicles none of them consider the effects that vibrations have on particular passengers' activities.

To address these issues, three different studies were conducted to investigate how low frequency lateral vibrations influence the passengers' ability to read and write onboard trains.

The first study was conducted on three types of Inter-Regional trains during normal service and included both a questionnaire survey and vibration measurements. Two proceeding laboratory studies were conducted in a train mock-up where the perceived difficulty of reading and writing was evaluated for different frequencies and amplitudes. To model and clarify how vibrations influence the processes of reading and writing the fundamentals of Human Activity Theory was used as a framework in this thesis.

In the field study about 80% of the passengers were found to be reading at some point during the journey, 25% were writing by hand, and 14% worked with portable computers. The passengers applied a wide range of seated postures for their different activities.

According to the standardised measurements, even the trains running on poor tracks showed acceptable levels of vibration. However, when the passengers performed a short written test, over 60 % reported to be disturbed or affected by vibrations and noise in the train.

In the laboratory studies it was found that the difficulty in reading and writing is strongly influenced by both vibration frequency and acceleration amplitude. The vibration spectra of real trains were found to correspond well to the frequency characteristics of the rated difficulty. It was also observed that moderate levels of difficulty begin at fairly low vibration levels. Contextual parameters like sitting posture and type of activity also showed strong influence on how vibrations cause difficulty.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , 70 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2006:24
Keyword [en]
lateral vibrations, passenger activities, reading, writing, sitting posture, frequency weighting, rated difficulty, field study, laboratory study, transient vibrations, stationary vibrations.
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-3974ISBN: 91-7178-374-1 (print)OAI: oai:DiVA.org:kth-3974DiVA: diva2:10236
Public defence
2006-06-02, D3, Lindstedsvägen 5, Stockholm, 10:00
Opponent
Supervisors
Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-09-22Bibliographically approved
List of papers
1. Effects of vibration on sedentary activities in passenger trains
Open this publication in new window or tab >>Effects of vibration on sedentary activities in passenger trains
2007 (English)In: Journal of Low Frequency Noise Vibration and Active Control, ISSN 0263-0923, Vol. 26, no 1, 43-55 p.Article in journal (Refereed) Published
Abstract [en]

The effects of vibration on train passengers' sedentary activities were investigated with a questionnaire survey as well as onboard vibration measurements. Three types of Swedish inter-regional trains were studied on four different lines. 330 passengers were randomly selected for the questionnaire survey. The vibration measurements were made at five positions around a passenger seat above the bogie during normal service. The vibration data were weighted according to ISO 2631-1 and the older German (Sperling) Ride Index Wz. Two-thirds of the passengers reported difficulties in performing sedentary activities such as reading and writing due to vibration and shocks. However, the standardized measurements did not reveal any severe discomfort values due to the vibration. This reveals that ISO and Wz standards do not evaluate vibrations effect on sedentary activities correctly. This also indicates that even low levels of vibration can reduce the ability to perform sedentary activities. Both chair and table produced more vibration than the floor. The spectral analysis showed that the chair had nearly the same frequency content as the floor, below 10 Hz. This range is critical since it coincides with the most vulnerable range for reading and writing as well as the perception of ride comfort.

National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-5756 (URN)10.1260/026309207781487448 (DOI)000248829400004 ()2-s2.0-36048977638 (Scopus ID)
Note
Uppdaterad från submitted till published: 20100921 QC 20100921 Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2017-12-14Bibliographically approved
2. Influence of stationary lateral vibrations on train passengers' ability to read and write
Open this publication in new window or tab >>Influence of stationary lateral vibrations on train passengers' ability to read and write
2008 (English)In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 39, no 6, 710-718 p.Article in journal (Refereed) Published
Abstract [en]

Recent studies on train passengers’ activities found that many passengers were engaged in some form of work, e.g. reading and writing, while traveling by train. A majority of the passengers reported that they were disturbed by vibrations or motions during their journey. A laboratory study was therefore set up to study how stationary low-frequency lateral vibrations influence the difficulty to read and write. The study involved 48 subjects (24f+24m) divided into three age groups. Two levels of sinusoidal vibrations were applied at nine discrete frequencies (0.8–8.0 Hz). Subjects performed both reading and writing tasks under two sitting positions (leaning against the backrest and leaning over a table). The judgments of perceived difficulty to read and write were rated using Borg's CR-100 scale. The results showed significant differences between the tasks and postural conditions. The subjects reported greater difficulty while reading and writing on the table than while leaning back. The frequencies up to 5 Hz had a particular influence on the perceived difficulty.

Keyword
Lateral vibration, Reading, Writing, Difficulty
National Category
Vehicle Engineering Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-5757 (URN)10.1016/j.apergo.2007.11.009 (DOI)000257904700005 ()2-s2.0-45249097606 (Scopus ID)
Note
Uppdaterad från submitted till published: 20100922 QC 20100922Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2017-12-14Bibliographically approved
3. Train passengers' ability to read and write during lateral vibration transients
Open this publication in new window or tab >>Train passengers' ability to read and write during lateral vibration transients
2006 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In a passenger survey aboard Swedish Intercity trains a majority of the passengers reported disturbances due to vibration and shocks. Subsequent laboratory studies revealed that the difficulty of reading and writing displayed non-linear frequency characteristics for stationary vibrations in the lateral direction. In the present study a train mock-up was used to investigate the effect of lateral vibration transients on passengers' ability to read and write. The subjects sat leaning against the backrest with the work material placed on their lap during the exposures. In order to limit the influence of anthropometric differences, 21 subjects were recruited according to predefined body measures. The study consisted of three experimental parts (A, B, C). Part A and B comprised of six discrete sinusoidal frequencies (1.25 - 5.0 Iiz) with a stationary amplitude of 0.3 m/s2. Each frequency was superimposed with transient peaks of three amplitudes (0.7, 1.0, 1.4 m/s2). The transient peaks were one oscillation period long and had a sinusoidal shape. Each peak appeared randomly three times during the 25 s long sequences. The test subjects rated their experienced difficulty to read and write due to each transient vibration, using Borg's CR-I00 scale. In part C, nine amplitude levels (0.43 - 0.7 m/s2) were used for three frequencies (1.25, 2.0, 4.0 Hz). In this part the test subjects were instructed to press a button whenever their reading was disturbed by a vibration transient. The results showed that occasional vibration transients cause lower levels of difficulty than stationary vibrations. Further did, only 35% of the shocks at 0.7 m/s2 cause a disturbance while reading.

National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-5758 (URN)2-s2.0-84883311615 (Scopus ID)978-162748150-2 (ISBN)
Conference
13th International Congress on Sound and Vibration 2006, ICSV 2006, 2-6 July 2006, Vienna, Austria
Note

QC 20141105

Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2014-11-05Bibliographically approved

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