Industry standards for quality seating

In the days before privatisation, British Rail undertook the design, manufacture and maintenance of the majority of components and systems which were used in railway vehicles. Passenger seating was no exception to this general rule. It is difficult to think of an organisation which conducted such an undertaking for a greater number of passenger seats other than British Rail. In an article on behalf of the BSI British Standards, Mr. Peter Matthews, Director of Poised Joint Management Ltd, explains the laws and seating standards now adopted by the industry to ensure maximum safety.

Whilst these issues were challenging, the situation offered the designers of the day unique advantages. The dependent issues of design, manufacturing and maintenance could be considered holistically and without some of the restraints that are in place today. Diverse subjects such as passenger comfort, fire performance and structural performance, were identified by BR standards, material standards, detail design and best ‘in-house’ practice. Among the last of the seats that we saw built in this way are those known as Inter City 70’s, which can still be seen on High Speed Trains (HST). This seat back molding was manufactured in Sheet Molding Compound (SMC) to BR detail design and required tooling which cost £70,000. At that time (early ‘70s), this was a huge sum which was justified by the long term build requirement spanning many vehicle classes and eventual quantities of approximately 70,000 units.

Law influenced seat design

During the process of privatisation the situation became more complex as different requirements and agencies exerted influence on seat design. The Public Inquiry into the Clapham disaster conducted by the then Anthony Hidden QC, had for instance required that seat design should consider the issue of “crashworthiness”.

Both Her Majesty’s Railway Inspectorate (HMRI) and the Rail Safety and Standards Board (RSSB) had responsibility for setting and maintaining standards concerning safety of the Railways, and the vehicle owners, operators, and builders had their own unique requirements. In 1995, the Law influenced seat design for the first time by virtue of the Disability Discrimination Act (1995). This, and the Rail Vehicle Accessibility Regulations (1998), required certain physical dimensions to be achieved and regulated on issues such as the shape and provision of grab handles and the use of colour to aid the visually impaired.

Seating standards emerge

These issues and diverse requirements were passed along the manufacturing supply chain by means of a series of performance standards. By a process of research and evolution these are now recognised as among the most stringent of the Railway organisations in Europe and in some cases they set world standards for the safety of passengers in all public transportation arenas.

Safety standards

Travel by rail is among the safest possible means of travel and incidents are extremely rare. However, the performance of the passenger seat needs to be considered in this very rare event to ensure that identified measures are optimised and maximised to aid the survivability of the passenger. The Association of Train Operating Companies (ATOC) standard AV/ST9001 was written on their behalf by RSSB, with the aim of providing a code of practice which identified conditions and measures where the performance of rail seating in crash conditions could be assessed and improved, and whereby the range and level of injury that a passenger may sustain is reduced to its lowest possible level under controlled and repeatable conditions. The standard ensures that Anthony Hidden’s recommendation has been fulfilled and that the lessons learnt from past incidents have been applied to design.

Similarly, fire on traction and rolling stock has been a concern because of the very special conditions of a travelling environment and restricted access and egress to rail vehicles. In practice, arson involving seat units is the most prominent cause of significant fires. To protect against these risks the rail industry has a suite of standards aimed at controlling the effect and development of fire. These are seen as the most stringent in Europe. Generally, Railway Group Standards refer to the British Standard BS 6853 and other British Standards which seek to jointly contain any fire and control a material’s reaction to fire depending on its location in a vehicle.

Vehicle manufacturers have to provide fire barriers at the ends, under vehicles and breaks within them in accordance with BS476 parts 20 and 22. Seat manufacturers need to consider the exposed surfaces of their seat with regard to the surface spread of flame requirements of BS 476 part 7. The fully assembled seat must also meet the requirements of BS 5852 – self extinction of ignition source 7, the largest and most aggressive source of ignition available in the testing regime with a fire load equivalent to four sheets of broadsheet type newspaper. The fire generated from this is required to self extinguish within 13 minutes and not pass to any edge of the seat. Depending on the location of the seat, type of vehicle and the infrastructure on which it runs, British Standard tests can also be required to establish and limit the ‘rate of heat release’, ‘propensity to ignite’ and the amount of ‘smoke’ and ‘toxicity’ of the products of combustion.

Durability standards

As well as these and other safety standards, operators and vehicle manufacturers also require seat suppliers to demonstrate the durability of their products. Here it is normally required to test the seat and interaction between seating components to another British Standard, BS 6261. This test is fondly known within the seating industry as the “Squirming Herman” test and consists of an articulated, human buttock shaped bolster, which is pressed into the seat base cushion and walked back along the seat base in a shuffling type motion; a loaded pad is then pressed into the back of the seat. This cyclical action is then repeated many times. For railway seating, testing is usually required over 500,000 cycles and takes several weeks to complete.

The manufacturer is also required to demonstrate that the seat is comfortable by a variety of objective and subjective measures. The seat is required to be acceptable for a cross section of the British adult population; people ranging between a small (5th percentile) female, to large (95th percentile) male. This objective anthropometric data is contained in the BSI publication. This and other guides and codes of practice aid designers to incorporate anthropometric and ergonomic measures into the seat design which help to ensure that the required subjective levels of comfort are achieved.

Standards support industry

BSI British Standards produces a wealth of information in the area of transport as well as standards which support many other industries. All formal standards are developed with a period of public enquiry and full consultation. They incorporate the views and expertise of a very wide range of interests from consumers, academia, special interest groups, government, business and industry. As a result, standards represent a consensus on current best practice. By developing standards in this way, the end user is also directly involved in shaping it.

Standards address quality, efficiency and best practice across the industry. It is not always enough to have the ‘best’ technological solution. Standardisation creates customer confidence and encourages market growth and technological evolution.