Re the question of Maryborough Ararat achievable line speed etc/ running time. On 47kg/94lb CWR rail on this section significantly higher running speeds should be achievable than the current 40kmh over 88 kms taking 3 hours running time for an average speed of 33 kmh (on century old 80lb CWR rail) .
Caveats: We either rationalize the existing grouped occupational crossings where the usual nanny state speed restrictions apply or rationalize and install protection.
First up we come to curvature over the 88kms there are 51 curves , but curves are generally of wide radius. Based on applying standard conservative Victorian applied cant with a max line speed of 80kmh only 4 curves would be speed restricted, and at a line speed of 100kmh then 10 curves would be speed restricted.
Gradient wise from the Maryborough end in order first up 15 kms with a max grade of 1 in 40, then 25kms gently undulating country , followed by 48 kms up to 1 in 50 into Ararat. (Maryborough elevation 240m Ararat 315m, so slightly up hill Mbh to Axt)
So with CWR 47kg/94lb rail if the railway were dead flat the existing curvature at 80kmh line speed should realize an ave speed of something like 79kmh over 88kms for a running time of 66 mins ; and at a line speed of 100 kmh an average around 98 kmh for a running time of 55 mins. .
Then one applies the gradients and that is a simulator job, given that in an ideal situation you can attain faster average speed simply by throwing more hp at the task. But in the case of say 3 x G class on a 900m train that is still a simulator job,
In summary the line does have 51 curves but generally curvature is fairly gentle, the line has many Ups and Downs generally 1 in 40 or 1 in 50 grades abound with only 15 kms of undulating easy going distance.
Now the higher the line speed generally the higher speed the train achieves approaching grades with more momentum etc . So would suggest broad brush with a line speed of 80kmh and existing hp to tonnage at 80 kmh line speed save 30 - 40 minutes, at 100 kmh line speed save 45 to 60 mins on the existing 40kmh line speed and 3 hours running time. (Viz: existing line speed 40kmh 3 hours at 80kmh line speed around 2 hrs 50 to 3 hours, and at 100kmh around 2 hrs 45 to 2 hrs 30 mins.
Who is an expert in this area. ?