Industry Insights

IPEX’s industry insights is a series of expert opinion thought leadership articles on issues on today’s railways.

Are you sitting comfortably?


Many new trains are being introduced with seats that are generally considered less comfortable than the seats on the trains they replace. Measure of seat comfort has always been a difficult aspect of train specification, and the most common solution to the problem has been not to write anything at all. This has resulted in the situation where as train manufacturers strive for slimmer seats to improve the overall capacity of the train and meet the customer’s capacity targets, so the comfort of the passenger gets ignored. This article investigates some of the issues surrounding seat comfort and puts forward a recommendation for future research.

The dilemma

The first time I rode on the new Thameslink train – that’s a nice looking train I thought. Then I sat down in the seat. Within two minutes I had back ache and had to stand up. Fortunately I was only going from St Pancras to Blackfriars. Imagine if I was going from Bedford or Brighton to London? I would have to choose to stand for the journey or buy a cushion.

thameslink seatsSo spoke a passenger giving their impression of the new Class 700s operating on Thameslink. Unfortunately this seems to happen more and more frequently. Testing the new Class 374 Eurostar trains, after 10 minutes, one’s rear end was quite numb. Two hours to Paris could well be construed as some form of torture. At this point, if one puts two and two together and notes that both these trains are from one manufacturer would result in scoring five, as the seats are manufactured by different companies.

IEP seats have also been written about. Roger Ford and Ian Walmsley both have written extensively on the subject of uncomfortable seats. So what’s happened?

As mentioned in the opening paragraph, often seat comfort is ignored in new train technical specifications. That’s because it’s actually quite hard to determine (please excuse the pun). One specification from 15 or so years ago stated seats should be “no harder than the existing trains” conveniently leaving to the manufacturer to determine the answer. Or so the writer thought. The manufacturer merely produced a seat and suggested the customer prove the seats were harder if they could. Stalemate.

Seat comfort measure

Seat comfort potentially has suffered as fire regulations have got more stringent, meaning that manufacturers will reduce the foam inside a seat to the smallest possible amount to ensure the tests are passed.

Added to which, there is an ever increasing demand to increase the number of seats in a vehicle. This can be achieved by increasing the length of the vehicle a la IEP, but also by slimming the seat back.

All this appears to have been at the expense of the passenger. The seat hardness can certainly be measured; there is a very handy standard commonly used by the Polyurethane Foam Association to measure Indentation Force Deflection (IFD).

IFD hardness tableIFD is defined as the amount of force, in pounds, required to indent a fifty square inch, round indentor foot into a predefined foam specimen a certain percentage of the specimen’s total thickness. For example the table above gives values at 25% Deflection (lb/50 insq. on 20″x20″x4″). However, is it fair to say that seats are uncomfortable because they aren’t soft enough?


One size does not fit all

Anyone over about six feet tall will tell you that travelling by train, although infinitely more comfortable than getting on a bus, is still not the most comfortable exercise. Some will make a bee-line for the priority seats, even if they are above the bogie as they give that extra legroom that makes all the difference.

Additionally, some seats have been set lower than knee height and leaves the tall user in an ungainly and uncomfortable semi-squat position. The seats on the BR multiple units that use the Mk3 bodyshell are classic examples of this, as are the “Mallard” seats on the Mk4 carriages. Interestingly the original Mk3 seats, although of similar height, are more comfortable, presumably because they are slightly more reclined. The question then is, what anthropometric data is being used for seat design, and does it represent the modern demographic of travellers?

A glimmer of an idea

desk chairIn the IPEX York “office” the seating accommodation for the desk is an IKEA chair made of laminated plywood. It has no cushioning at all, excepting the gas strut, and yet an eight hour session in front of the computer is not a chore, and twelve hour stints have been undertaken without ill effect. So why should this be so comfortable and yet some more padded seats be less so? Office chairs are designed to be sat in all day. Seats on trains are not, but intercity trains should really be designed with that same ethos.

We believe the answer is that the office chair can be adjusted. The IKEA chair in question is not a fancy seat; it only has one adjustment, but a crucial one – seat height.

The main requirement of a comfortable seat is that the user’s upper legs are parallel with the floor supported by the chair along their length. If the seat is too high, undue pressure is put on the back of the legs behind the knees, and if too low, undue pressure is put on the buttocks.

Concluding remarks

Imagine if height adjustable seats were introduced onto passenger trains? There would be obstacles to overcome, such as how to work the mechanism and how to make it robust enough to cope with the demands of the travelling public and the occasional wilfully destructive occupant.

adaptable carriageHowever, research into this may well provide the answer to the comfortable ride that has alluded so many recently. Given the plethora of research into seating such as the “adaptable carriage” for carrying freight off –peak, there is no reason to suggest that such a concept would not attract funding or that the funding would be misplaced.