On the topic of long closed and proposed rail lines…
The following proposed Nerang Murwillumbah railway routes, with July 1900 in the surveyor's handwriting, is available as a 5mb JPEG from my Google Drive site. All the proposed routes would have required a rail bridge over the Tweed River. In that proposed time period were two Tweed River road bridges with very high cost lifting span equipped sections; the 1901 Murwillumbah road bridge and the 1936 Barney's Point Bridge over the Tweed River at Chinderah. The 1936 highway bridge had liftings spans as the Tweed River trade in the 1930s was still sufficient to force the inclusion of a lifting span, therefore the same river trade would have also forced a similarly expensive lifting span on any rail bridge built in that era. A rail bridge with lifting span was possible as shown with the Grafton rail lifting span which also showed 1930s river trade was sufficient to force a lifting span at Grafton as well.
The distances on the 1900 plan are a bit odd as the 141 miles shown for Murwillumbah is interesting as Stokers Siding, 6 miles south of Murwillumbah, was 141 miles 42 chains by rail from Grafton as per the 1918 NSWR Northern local appendix. The Casino Grafton line opened 1905 and the map is dated 1900, although the initial Grafton - Casino surveys would have probably been done by 1900.
Another proposed but not built rail route was along the north side of the Tweed river south from Tweed Heads. The proposed Chinderah station site, slightly upstream of the 1936 Barney's Point Bridge, is marked with my usual blue arrow on this cadastral from The Tweed Heads Historical Society. On the left side of that plan is portion 174 marked as John Sexton's land thus Sexton's Hill on the highway near there. John and Bridget Sexton had a daughter Ellen who eventually married a widower from Brisbane who was a member of QLD parliament. That is how the Sextons of Sexton Hill became the parents in law of Vince Gair, future QLD premier and Commonwealth Senator.
Chinderah proposed but not built railway station site https://drive.google.com/file/d/0ByB-ppGeDyvwQ2RNSTZHYWduRk0/view
The station yard plans for most stations Ernest Junction to Tweed Heads.