Place it at the end of a station sequence, just after the platform crowd shot, then follow it with a bell ding to mark the train pulling away. Keep it as the final beat before a cut to the moving train, with the next scene starting inside the carriage.
About this sound
This 4.6-second clip captures the chime and sliding shut of the doors on an older Singapore MRT train, with the mechanical movement and warning tone heard just before departure. It feels instantly familiar and slightly hurried, like the last moment to step aboard, and it carries a small nostalgic pull for regular riders who remember the older trains.