Incredibly cool John, thanks for pointing this out. Who made/maintains this?
Interesting, looks like this might be the same interface as the map I use for the RGS.
The National Library of Scotland also has a nice selection of maps for the UK of old and abandoned railways.
When looking for one thing, I came upon another...
Abandoned & Out-of-Service Railroad Lines - Google My Maps
Way cool and it's worldwide too!
While the entry from my country includes the Cibatu to Cikajang line (personally I called this line as "Cikajang Line"), in fact the first half of this line from Cibatu to Garut is already rebuilt as part of preparation for reinstating passenger service from Garut to Bandung and beyond (even the "Cibatu local train" currently serving Purwakarta - Cibatu corridor is planned by Indonesian Railways to be extended all the way to Garut station, once the construction work for new building of Garut station has completed and is ready to be reopened for public).
That's excellent to hear/read at least the line is being rebuilt.