Only things that actually exist should be mapped.  So things with a presence.  I highly doubt there is a railway (abandoned or not) going through the person's bedroom at 3315 Gregory Street.

See more here:
https://wiki.openstreetmap.org/wiki/Good_practice#Map_what's_on_the_ground

This would definitely be good stuff to add to OpenHistoricalMaps where it can live on forever.  Features that no longer exist but once did and have been overbuilt belong on OHM:
https://wiki.openstreetmap.org/wiki/Nonexistent_features#:~:text=Please%20feel%20free,right%20time%20period.

OpenHistoricalMap (OHM) also allows you designate start and end dates for features.  I highly recommend focusing time and energy getting old railways added there so you don't have to worry about them being deleted over time:
https://www.openhistoricalmap.org/
