The Monto loop was a result of competition between coastal railway centres, separate lines from Maryborough and Gladstone reaching the town in 1928 and 1931. Built mainly to access mineral resources, the loop saw mostly light traffic in agricultural produce.
The loop was never used for diversion of main line traffic when the Maryborough-Gladstone line was blocked, because the section between Mungar and Mundubberra had light rail, sharp curvature, and steep grades. It could not accept main-line engines.
The section from Gladstone to Monto was better built, but the ascent of the Dawes Range required no less than six tunnels, and a ruling grade of 1 in 33.Traffic was heaviest between Monto and Gayndah. The loop escaped closure in the 1960s, but now has no traffic, the branch being "redlined".
Approximate run time: 35 minutes.