Paul Tomlinson
Graham, Hi. You may be interested in reading the Newsletter that heralded the introduction of the track – link below. The reason for the spare rail is that the track has been designed to create prototypical 60ft panels, which don’t fit neatly into the yard/metre length of the standard rail.
https://emgs.org/wp-content/uploads/2021/02/EMGS-Newsletter-219-January-2019.pdf