I recently read an article concerning Taiwan Railways and their new tilting trains apparently the seat design spells discomfort for anyone over the height of 170cm ,because of the seat design . Then I found another article on the web that contradicted this notion, describing the virtues of seats on Taiwanese trains The second article seemed to suggest they are appropriate for tall people and also criticize seats in Holland where it was suggested that there was poor accomodation for very tall people , even though people in Holland were taller than the average . These comments were part of general stories from the net and I wonder where the truth really lies . Whilst we can be amused by this ‘runaway train ‘ of comments (forgive the pun!) there is absolutely a serious side to this discussion .
How do we design seating to suit a general population ? We might say in Taiwan the average person is small and in Holland the opposite ,but what about peple who come out at the smaller end of small or the taller end and similarly for the Dutch population? The answer to this problem is to use particular ‘modelling ‘ , Design Engineers utilise the following considerations :
HUMAN FACTORS AND ERGONOMICS
is the comparative study of human body measurements and properties.
is the science of making work environment safer and more comfortable to workers using design and anthropometric data.’
ANTHROPOMETRIC DATA ?? eh – well ANTHROPOETRIC DATA basically is a collection of body measurements taken from a particular population . It is often presented as a table or annotated diagrams of human figures.
The mearsurements are the legnths of body parts (for seat design) .All data used in seat design is regularly updated and set into National and International standards, the standards are reviewed and updated regularly , they provide guidance to meet minimum requirements and aim to cover greater ranges of the population .
The ‘GRAPHIC’ representation of populations usually shows the SMALLEST to the AVERAGE to the TALLEST , of course there are advantages of designing close to the AVERAGE population. Divisions and ranges are called PERCENTILES , these are chunks of information taken from the distribution and thus can be used to represent parts of the population, the problem is also in the whole range chosen
- body dimensions of the 5th percentile small female to the 95th percentile large male . This range covers onlyy 95 percent of the population and is intended to meet the MINIMUM requirements of users. Some users will obviously be missed .
Some of the problems encountered with using data collections is that of course it might always represent a limitation , also ‘sets of data’ may be affected by :
- Changes in diet
ERGONOMICS WITH HUMAN FACTORS ????
These terms are probably synonymous . ie Human Factors and Ergonomics and is really an eclective contribution of , psychology, engineering, biomechanics, mechanobiology, industrial design, statistics and operations research, it is an ever growing field.
The International Ergonomics Association defines ERGOMONICS or HUMAN FACTORS as follows:
‘Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance’.
All this sounds good but after a long journey on a train with an aching neck and back does it really mean anything TO YOU.
Its a difficult thing to create design that fits all , perhaps the answer might be understanding your own needs and body ‘sizing’ and having methods of creating personal MODIFICATION . Seats in offices should be adjustable around the ‘percentiles’ using ‘levers and screws’ that operate tilt mechanisms and lumbar and neck cushioning.
IN FACT WHAT DOES MAKE A SEAT COMFORTABLE ?
Legs should be on the floor and not dangling , to get a good position and prevent pressure being exerted under the thighs to reduce circulation.
Also the width or depth of the seat should allow for enough clearance for the legs to prevent interruption of circulation .
The natural curves of the back (lordosis for low back , kyphosis for mid back) should be supported well by the seat
The main weight bearing should be taken by the bones of the pelvis (ISCHIAL TUBEROSITIES) and top half of the thighs.
Also change of posture at regular intervals requires space for a ‘FIDGET factor’; even perfect posture must allow for movement.
So again if the seat does not provide us with enough comfort personal MODIFICATION is the only option . LUMBAR ROLLS are very useful and can be purchased for a small price , they are portable and light .
GENERAL ADVICE :
Dont carry too heavy or irregul;ar loads/bags
MODIFY the seat using NECK TRAVEL PILLOWS AND LUMBAR ROLL.
Another simple idea is to use A ROLLED UP wooly HAT FOR THE LUMBAR and a ROLLED up scarf for the neck , anything you have will be usefull however its best to use items that are EASY to hand.
If you are able to place your bag at your feet , PLACE FEET ON THE BAG to support and lift them , this has the effect of PUSHING the lumbar curve back into the seat . This idea is limited by worrying about soiling your bag (maybe utilise a free newspaper to protect it!)or annoying your fellow travellers .
TAKE REGUALR breaks if you can and also be happy to FIDGET.
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