Goal: The Cairns-Hinterland rail system is negotiable only at certain river crossing & via Redynch & Kuranda. See if you can export some of the wealth!
Author's Comments: This map has been constructed so that you can only get inland by going up the Kuranda Range from Redlynch to Kuranda to Biboorah to Mareeba.
In this scene, there are certain places that you can only get across the river systems because of the way the rivers are constructed.
This is one of the challenges. Don't get frustrated but take things easily and test, test, test those gradings.
Also you should be able to construct the inland line from Redlynch without using a grade over 4.0 . If you grade colour indicator goes into the red, you know you are not on the intended rail routing.
I would suggest that the coastal system be developed first, as you will need some huge funds to construct this system to Mareeba and beyond.