Are You Sitting Comfortably?

Although a number of new train fleets have been introduced onto the British rail network in recent years, with more still to come, they haven’t all met with universal passenger approval. Some have described the seats as “ironing boards”, a reference to their comparative hardness. Others have observed that the initial impressions might lead one to think that the seats are hard, but in fact they remain comfortable after a long journey.

After a safe and punctual train, seats are probably the most important customer requirement, but, with people coming in all shapes and sizes, and journeys being for a variety of purposes, customer requirements for seats would not come into the category of “one size fits all”.

In days gone by, the importance of seats would be inferred by a requirement that seat comfort be judged by the managing director and his (in those days it was inevitably a man) directors – a process that survived until at least the 1990s.

More recently, enlightened project directors have organised customer clinics and provided the seats that the customers liked most. Less-enlightened project directors have bought the cheapest seats compliant with the various requirements (that do not include comfort).

Then there must be a special mention for project directors who organise a customer clinic but then buy the cheapest compliant seat, irrespective of the result of the clinic.

Compliance is everything, and modern trains must comply with the interoperability regulations. In the case of seats, train buyers have to ensure that the seats meet some pretty basic ergonomic requirements, show they are strong enough in service and in a crash, and meet stringent fire safety requirements.

Moreover, a train operator’s franchise agreement might require a particular number of seats to be operated into and out of key nodal points at specified times. Comfort might be an objective, but without means of measurement.

Claims have been made that compliance with fire safety standards leads to hard seats, others disagree.

The result has been a large number of complaints about so-called “ironing board” seats, and recent customer satisfaction scores show seats (at 67 per cent) fall a long way short of overall passenger satisfaction (at 83 per cent).

All this led to RSSB commissioning research into seat comfort, with the aim of producing objective criteria for assessing seat comfort and, hopefully a standard against which compliance may be measured. If customers dislike the seats on a new train when this process is in use, it will be easy to see whether the specifier has been too undemanding or whether the seat supplier has failed to comply.

Comfort factors

RSSB Research Project T1140 “Defining the requirements of a seat comfort selection process” was initiated in February 2018 and the final report was delivered in May 2019. The work was carried out by Arup and the Furniture Industry Research Association (FIRA).

The report highlights that “quantifying seat comfort is a complex area that depends on the human, the product and the environment…comfort can be defined as ‘an absence of discomfort’ and so discomfort is sometimes easier to quantify”. Putting this into a mouthful of other words, the different shapes and sizes of passengers, and the activities they perform whilst sat in the seat, together with the shapes and sizes of seats, seat pad compression, variations in journey length and train vibration, can and do affect feelings of comfort.

The project set out with a literature review which was used to help define minimum seat comfort requirements, to develop a seat comfort test methodology and seat comfort scoring system and, finally, to test and validate the proposals.

The report identified ten factors; seat dimensions, passenger anthropometry, passenger activity, train seat arrangements, static, dynamic and temporal factors of comfort, psychosocial factors of seat comfort, seat durability, international best practices regarding seating, seat ‘accessories’ such as folding tablets, power sockets, and ancillary items that effect the passenger seating area and legroom such as tables, possible future train seat design scenarios which, together with Arup’s and FIRA’s background knowledge and experience, were used in the subsequent stages.

The project team worked on the four key factors that influence seat comfort. Firstly, the journey type, as passengers expect different comfort levels on different types of journey. For example, people may tolerate a lower level of comfort on a short journey compared with a long one.

Secondly, the dimensions and weight of people with the objective of determining minimum dimensions suitable for the majority of the population from large to small.

Thirdly the seat pad, as most of the complaints about seat hardness come about when people first sit in the seat and find the seat pad to be unyielding. The pad thickness, hardness and durability are important factors. Indeed, if a seat pad looks reasonably thick but feels hard the impression of discomfort might be increased. For a comfortable seat the pad must provide enough compression for lighter people and enough support to prevent the pad “bottoming out” (sorry!) for heavier people.

Finally, seat accessories such as armrests and tables are valued by customers and were included in the process.

Results

As people and their journeys vary so much the report recommends a number of seat factors be evaluated for each category of journey defined.

Journey types

Four types of journey were identified – metro, regional, inter-city and first class/very high speed. For each journey type, a comfort rating scale was proposed, made up of four attributes; seat dimensions, seat pad requirements, seat attractiveness and seat accessories. Each of these attributes is described in turn.

Seat dimensions

The report proposes minimum seat comfort dimensions to ensure that a seat’s features such as seat depth and legroom will fit the majority of the UK population. People’s sizes were defined from “BS EN ISO 7250-2:2013 Basic human body measurements for technological design, part 2: Statistical summaries of body measurements from national populations” and a test method was designed using a weighted chair measurement device, to be used in accordance with “ISO TR 24496:2017 – Office furniture – Office work chairs – Methods for the determination of dimensions”.

A number of dimensions were specified; either pass/fail or varied by type of journey. These included seat height, depth and width, backrest width and armrest height, the position of the headrest, legroom and the angle of the seat itself. Figure 1 shows the dimensions and scores for the four journey types.

Seat Pad Requirements

For the seat and back pads, the following attributes were specified – seat pad minimum thickness, seat back minimum thickness, seat pad hardness with 500N load, seat pad hardness with 1100N load and long-term seat durability. Figure 2 shows the full table.

Although there are only five requirements, this is probably the most difficult set to deliver a good score, as an appropriately ‘soft’ seat that scores highly on the compression test might not perform so well on the durability test.

Seat Attractiveness

This attribute takes account of the complex nature of determining comfort. It is a qualitative, survey-based measure, and is intended to help a train operator decide which seat to choose from candidates that have passed the dimension and compression tests. The three attributes are:

• How comfortable does the seat look?
• How attractive is the seat?
• How comfortable is the seat to sit in?

What does this all mean in practice?

There is a total of sixteen objective measures and three qualitative measures. Minimum requirements are listed in figure 3. For the eleven seat dimensions alone, the fail criteria and the maximum scores for each of the four journey types are shown in figure 4.

As an example, the maximum score for a Regional train is 25.5 and, as part of the evaluation, three sample seat types were compared, shown in figure 5. It is interesting that one seat is a clear winner, but even this good seat might still fail if the seat pad requirements were not delivered or it was disliked in the qualitative assessment.

Neither spacious seats with poor padding, nor well padded but cramped seats are acceptable.

Conclusion

When this project was commissioned, its objectives were to:

• Define minimum (baseline) requirements for train seat comfort;
• Create a seat comfort test methodology with scoring system that allows TOCs, ROSCOs, seat manufacturers and seat suppliers to test and score a range of seats for comfort;
• Test and validate the requirements;
• Improve seat comfort on UK trains.

In addition, the seat comfort specifications, testing and scoring methodology had to be robust and credible and to be accepted by the rail and train seating industry. The requirement is not intended to be a barrier to new innovative seating solutions, but to promote it.

Many were sceptical that objective criteria for seat comfort could be set, and it is laudable that a practical system has been developed in a little under over a year. It remains to be seen how well this works in practice, but any reasonable review of the requirements shows that some significant improvements will be made if the requirements are indeed incorporated into the Key Train Requirements document and hence into contracts.

Your writer wonders, however, whether any operator would have the courage to specify seat comfort values at the bottom end of the ranges suggested for the various duties and, indeed, whether some of the minimum dimensions specified spell the end of 3+2 seating on future UK size rolling stock?

Further, do these requirements help resolve the situation where legroom is compromised because body side heaters encroach into the space of window seats?