rgsonline have the GMRT standards. Something like GMRT/2100 which deals with crashworthiness and loading of rail vehicle structures and from memory, it also deals with interior aspects. These documents are updated as technology advances but also in response to incidents and findings by bodies such as RAIB.
It has been found, for example that ceiling panels falling are the main (most frequent) cause of head injuries in derailments and collisions. Recommendations are made by the RAIB, and in time the standards are updated.
I *think* that it has been found that these larger and higher backed seats are found to provide more support in rapid decelerations associated with collisions or derailments. Also, there is a minimum radius for edges and corners which also tends to make them larger than they were in years gone by.
--- old post above --- --- new post below ---
Extract from GM/GN2687:
GN107 For a passenger with their back to the direction of travel, with a low seat back, the most likely injury mechanism occurs as the head rotates about the neck into or over the seat top and then rotates in the opposite direction as the body rebounds from the seat back. To avoid this type of injury and also ‘whiplash’ injuries, limits on neck rotation and neck injury criteria are specified. The most straightforward method to meet the requirements set out is to use high backed seats but alternative approaches can be adopted provided that the performance criteria are satisfied.
GN108 For a passenger projected forward in a collision with unidirectional low seat backs there is the additional risk of passing over the top of the seat in front with the possibility of more serious injuries for themselves and other passengers.
--- old post above --- --- new post below ---
In addition:
GN109 The seat height dimensional requirement (set out in 6.2 of superseded document AV/ST9001) should be regarded as empirical as it has not been possible to trace the technical provenance. The resulting maximum seat back height is typically between 1280 mm and 1290 mm above floor level. The 25 mm dimension has been amended to 20 mm for consistency with automotive headrest standards.
GN110 Rail vehicle disability regulations (PRM TSI) specify seatback handholds at between 800 mm and 1200 mm above floor level (4.2.2.2.1 of PRM TSI) which could limit the practical height of a seat, depending on the shape of the seat back. In determining an optimum seat height, wider issues such as the requirements of CCTV systems and passenger security should also be considered.
